Eastman51

I recently got my 83 FB out of winter storage and driven it a couple times. We've had some cooler weather more recently and its not as enjoyable to drive, but some buddies and I had a planned road trip to a nice road a few hours from here so despite the poor weather I've been trying to get a few things sorted. Namely brakes, but that's not today's problem.

I was informed by some people in another online community that my fan clutch was dead. It has a lot of resistance regardless of temperature, and I can say for certain its locked at any rpm above idle. I'm fairly certain its been loud ever since I bought the car, but I had never thought anything of it; just assumed that it was an old car/car with mech fan thing. I mentioned off-hand in the other community that my oil gets hot on the highway on hot days, and that I thought my coolant temp gauge went up slightly too. They had me check the fan clutch, and told me it was dead so I either needed to convert to efan or get a new fan clutch. Seeing the cost of fan clutches, I went with efan instead. I did a lot of research on here, where I basically learned this: clutch fan is best, but efan works just as well if you have enough cfm and whatnot. I got a 16" flex-a-lite fan recommended to me by the other community. Picked up a decent fan controller as well that has a digital display and is easy to set the temperature on. Got it all installed yesterday and it worked right away, did some testing and thought I had it set for a good temperature.

However, when I actually went on a test drive, my oil temps ran up really quick and I also immediately noticed that the oil takes far longer to cool off after coming to a stop. Today I ran the car on the highway at 75mph and even the coolant temp seemed to creep up slightly, in addition to the oil temps spiking to numbers I've only ever seen on a really hot day clocking 68mph with the AC on.

Some background on the car's cooling system.
With the clutch fan, oil temps would spike to 210 if I ran the car hard at WOT through 1st and 2nd gear. Then the oil temp would drop to about 190 or so if I was just cruising through town, with the oil cooling to 180F within a minute at stop lights. On the highway it would run about 200F, but creep around 210F on hotter days (occasionally reaching 220F maximum with the AC on). Getting off the highway, the oil would cool to 190F very quickly, and then spend a few minutes heat soaked before dropping to 180F gradually. I have an Autometer oil temp gauge with the sender in a Mishimoto sandwich plate at the oil filter. I have the stock beehive. I didn't have the oil temp gauge for the longest time, so I was blissfully ignorant until I installed it last summer after replacing my clutch.
I only have the stock coolant temp gauge, which is as slow and questionable as the fuel gauge. Originally, I never ever had issues with the temp gauge. It would get up to about 1/4, maybe less, and stay there never changing no matter the weather. In spring 2020 (I'd had the car for like 6-7 months), I flushed the cooling system and replaced all hoses and clamps; new thermostat from Atkins, and a new radiator cap. Fresh coolant, and bled it thoroughly. Still never any change once warm. I had some issues with belt tension, shredded belts, belt squeal, etc; I had swapped to an S4 FC alternator with a Banzai pulley since I deleted the smog pump. Could never get the belts to not squeal and even shredded one completely; ended up getting the banzai alternator bracket where things seemed to return to normal from there. However, I noticed quickly that on the highway, the temp gauge would creep up to near halfway; didn't think on it too much but was concerned since it had never acted like that before. In fall 2020 a buddy pointed out to me that he smelled burning coolant from my engine bay after we had driven around for a while. In spring 2021, after coming out of winter storage, I determined that the coolant smell was from the water pump housing gasket after seeing fresh coolant on the front cover right under the water pump housing; so I replaced the water pump and the housing gasket. When my coolant temps still creeped near half, I chased it down to belt tension. I had the banzai bracket tensioned super loose. Using a v-belt tension tester I got the belts exactly to the spec listed in the FSM, the overheating disappeared and my voltage became much more stable. Later that summer, my pilot bearing sezied. I pulled the motor to replace the clutch and oil pan gasket (also because my driveshaft was stuck to the diff, no hammer could break it loose); while it was out I tore the intake manifold off, discovering the o-rings were shot and coolant had saturated the gasket. Filled the holes with freeze plugs. Engine went back in and all was well, installed the oil temp gauge not long after and noticed the above oil temp behaviors. I could find basically no actually useful information online about what oil temps should be with the beehive, and asking around in other places I basically learned that everyone either tossed the beehive, had an fmoc, or already had oil temp plagues of their own on an fmoc. So I just kinda left it be and kept an eye on it just in case it might get above 220F.

Now we fast forward to this spring. We've had a couple hot days, where I drove the car to work and for fun. On the highway I noticed the coolant temp gauge seemed to creep up slightly, but I was not entirely sure if I was just being paranoid or not. Learned my clutch fan was dead, and now here we are.
What I've learned so far with the efan in my limited testing is the following:
Coolant temps seem to be slightly less stable than before. At speed the gauge seems to creep up slightly, but at low speed and idle it does not move even when the fan cycles. I've been borrowing a buddy's IR thermometer for rough estimates, and have the fan controller set to turn on at 148F; this seems to be a balance between what the probe sees in the radiator and what the IR thermometer sees at the rear iron and the thermostat housing. I'm pretty sure this is keeping the coolant below 180F, which I've done mainly as a safety until I figure things out. The fan seems to run for a minute or two I believe, but I have not timed it; the controller is programmed to drop the temperature by 10 before kicking off.
Weather has been so poor I can't drive around with the window down to hear whether the fan kicks on at low speed or not, I can only hear it kicking on/off at idle when stopped. I'm not overly concerned about coolant temps, but at this point any little thing is under major scrutiny from my paranoia.
Now, my biggest complaint/issue is the oil temps. I haven't beaten on it hardly at all, since I'm a little scared. Oil temps seem to run up to 200F just casually driving around town. And this is in roughly 50F weather with strong gusts of north wind. Before it would only do about 190F in city driving no matter what the weather was. I timed it at 5 minutes to cool from 200F to 185F, including 25mph or slower driving, coasting, and sitting at idle with the fan cycling. On the highway, oil temp pretty quickly goes up to 210F and stays there; going above 70mph and it will creep very slowly to 220F and stay there until I can stop, if I turn off to a road and go 55 it will very slowly settle back to 210F. In contrast, it would never ever get this hot on the highway in similar weather with the clutch fan. More like 200F oil on the highway, at most; hotter weather would yield the 210-220F numbers.

I'm being told by other communities a variety of things:
-my airflow sucks because I'm using efan
-something is wrong with my cooling system as a whole
-no one knows anything about the beehive at all
-I should get an FC fmoc
-my oil shouldn't get this hot to begin with
-FC owners have oil temp issues with efan
-the person who recommended the fan has a short alu radiator and an fmoc, and has no issues at all with this fan.

And I can find absolutely nothing about what my oil temps should be via google search. I'm lost and none of my usual channels are helping me figure things out on this.
Any thoughts, suggestions, temp numbers, etc, would be great.
Should I try to return the efan setup stuff and put my fan clutch back on? Should I pony up for a new fan clutch or just continue using my fan clutch as is?
I don't have the ability to fabricate anything, so if I should get an fmoc, how am I going to mount it? I would definitely want something functional and easy to do.
One last plot twist, I have to put the car back into storage in two weeks. Ideally I would like to fix this issue before then so I can go on that roadtrip and enjoy the car with no troubles as much as I can before I park it back up.
I absolutely adore this car, but sometimes it just stresses me the hell out; some things I can never seem to resolve no matter what. When the car works, its a real joy; but lately I've been having more fun dealing with the shenanigans of my project Toyotas. On those, its a fun experience; diagnose this, replace that, repair whatever, problem solved for good. I get so paranoid about destroying my precious little 12A because of something stupid; motor is only at 81k original and runs beautifully most of the time (mainly the shutter valve sticking occasionally after cold starts and probably a fuel delivery issue).

Edit: I just had the idea to reinstall the stock fan shroud over the efan. Perhaps it could help while at speed?

Thanks for keeping up and I really appreciate any help I can get here!
I've got some pics attached below. If my coolant gauge goes any higher than depicted, it is just barely noticeable.

chirmstream

Kind of a band aid fix imo, but thoughts on putting in a bigger radiator?

Eastman51

I've thought about it before, but name brand ones cost more than a fan clutch. And at that point, why not try to get an fmoc? Supposedly fmocs are superior to the beehive after all, oil temps seem to my biggest problem no?

Maxwedge

iTrader: (1)

On a street driven car the Beehive works just fine, even on "spirited" driving with occasional autocross on weekends. Something else is wrong with your cooling system.

I know everyone thinks they're "trick" but e-fans don't gain you any power and only complicate things. A new fan clutch will give you 100k miles of daily reliability. Are you sure you hooked up your e-fan properly? What's with that goofy/cheap temp sensor stuck to the radiator fins??? The temp sensor that turns the e-fan on needs to be a ccolant sensor in the proper place, not a stick-on epay special. Seems like the cheap-way is making you run hotter. New fan-clutch is reliable and simple to install. $200 well spent.

Your other forum sucks.

chirmstream

I should have looked closer at the pictures, I didn't see that temp sensor. Everything Maxwedge said is correct, your temp sensor needs to be a coolant sensor in the flow of coolant going through the engine (you know, like how the factory sensor is).

Eastman51

I am aware the radiator probe is not accurate. This is why I have the fan set to switch on when the probe reads 148F at the present moment.

I thought to get a sending unit to put inline of the top radiator hose, but it would have made the install more complex; at which point I would like to add a standalone temp gauge at the same time. However this fan controller uses a proprietary connector afaik, requiring their own kit for an in-hose sensor.
From what I understand, these radiator probes, while obviously not accurate, are at least consistent; so once the controller is properly set it's not a problem.
I am also totally aware there's no power gain removing the fan clutch. I just couldn't justify $250. I have bought a car in good enough shape to daily drive for not much more.....

Eastman51

Ok, if there's something wrong, what should I check?
The thermostat seems to be perfectly fine. My only ideas could be the radiator itself or the beehive.

Eastman51

The efan install was simple and easily reversible. No stock wiring was harmed in the making. I can hook up an AC override, either to a manual switch or to the AC wire but I haven't done that as I want the car dialed in first (and I don't usually use ac while standing still anyway).

I am also 100% certain the fan is hooked up correctly. I followed the instructions included with the fan controller, and paid attention to the fan wiring to make sure it was hooked up for pulling.
The temperature to trigger the fan may need tweaked, but otherwise it is working very well for the coolant; it's mainly just the oil that seems to be overheating.

Richard Miller

there is a helluva gap between the fan and the radiator. I can't see it efficiently pulling air through the radiator. Do your temps run high on the freeway where the fan is not utilized?

LongDuck

First off, the detail provided in your short essay helps with suggestions. Here are mine;

1) Thermostat - replace it. Again. The jiggle-pin goes toward the top when you install it, and if the thermostat doesn't ever get out of bypass mode, it will cause high engine coolant and oil temp readings, because the coolant never makes it to the radiator. If you're good at diagnostics, test the one you pull out in a boiling pot of water. If not, just replace it - they're not that expensive, and it's the easiest fix to your problems.
2) Radiator - Yours looks original. That means it's almost 40 years old. Any radiator that old will have seen a lot of corrosion, even sitting in a garage. The green dried up crust around the edges is seepage from leaks, but your bigger problem is internal passages blocked by calcium deposits or just engine crud. The best fix is a new radiator, either OEM or KOYORAD aluminum. The cheaper fix is to have a radiator shop boil it out and rod it, cleaning out the passages. This will definitely help with coolant flow, and if your engine is running hot at 50F, it will overheat at 80-90-100F (*I live in the Sonoran Desert, so 115-120F is common).
3) Airflow - Electric fans suck. The good ones draw him amperage and overtake your stock wiring and alternator. The bad ones never pull enough air because they weren't designed to deal with the heat of a rotary. Mechanical fan clutches are very reliable, fail safe (*they fail by locking up, typically), and while louder than electric fans, they just work. Electric fans also lack the proper shrouding to pull air THROUGH the radiator, allowing air to go around it. Also, never run the car without the radiator header plate - that flat plate in front of the radiator that completes the box - as it is needed to force air through the radiator. If you don't have the undertray installed - put it back on. This will help the air coming in the front to be forced through your radiator (after the condensor). On that, make sure your condenser and radiator fins are clear of debris and undamaged. A blocked condenser will prevent good A/C, but also block airflow to the radiator.
4) Timing - If the timing is set either too advanced or retarded, it will cause heat issues. Get a timing light on the front pulley and verify that it's set correctly for both leading and trailing; look up the specs for your year and model. Make sure you're running Denso BR8-EQ14 plugs. These are the right plugs for ALL 1st Gen cars and are proven to work.
5) Coolant - When was the last time you changed it? Did you use distilled water? Did you mix it to 50/50 with a quality antifreeze, which also alters the boiling point? When was the last time you changed the radiator cap? The rubber gasket will erode over time, preventing pressure from building which helps to increase the boiling point, but here you're just giving it all a tune up and overhaul. Make sure the overflow bottle is topped up and not leaking. Blow through the lines to be sure it can breathe, and that the radiator is full to the top wih coolant.
6) Oil Pressure - Oil pressure is just as important as oil temp. If your oil temps are running over 200F (*And you trust your gauge accuracy), you're cooking your oil. Change it regularly, as those high temps will boil off the long chains that prevent engine wear on parts. The beehive works fine even in hot climates, but not iff the cooling system is barely hanging on. FMOC gets a lot of love, because it gets more clean, cool airflow, and works more efficiently overall.
7) Your "other" forums suck. Stop trying to get advice there. These cars are unique in their engine type and specifics. General knowledge will only get you so far, and often down the wrong road.

The rotary engine sheds 1/3 of its heat through the engine oil cooler, 1/3 through the coolant system to the radiator, and the remaining 1/3 through a diabetic cooling, as in heat being shed to the environment through the irons, housings, etc. You need to look closely at the first 2 areas, as engine temps this high sill quickly lead to cooking oil control rings, sealing rubbers on the irons, and eventually apex, side, and corner seal springs leading to a loss of compression.

Post back with your approach on these things, and the board members can help you prioritize for cost. Good luck,

Eastman51

I am back and armed with some data.

Using the IR thermometer, I saw that with my current fan settings, the thermostat was not being allowed to stay mostly open. I've bumped the setting up a few degrees and may bump it up even more so that 180F stays the average nominal temp at the Mazda logo on the rear iron.

After bumping up the fan setting, the coolant temp gauge on the dash went up just a tad. About where it was when I was driving around on the highway yesterday. So I believe that is the actual operating temperature position now, since I've confirmed that temps at the rear iron are within 10F +- of 180F.
The previous setting was holding the temperature at 160-170F at idle, which explains why it would drop the needle.

Now onto the oil temps.
According to the gauge, oil temps do not exceed 210-220F depending on speed (220F generally being cruising at 75mph).
Now, if I get off the highway and pull over safely and check the temperature on the oil filter itself we see that the gauge reads somewhere around 200F or so, hard to say since there's not a ton of markings on it. If I measure the oil filter with the IR thermometer, it says about 190-195F.
when the gauge reads 180F after idling for approx 5 min, the IR reads about 183 on the oil filter. This is to be expected by my expectations, after all the oil cannot be cooler than the engine coolant itself with this setup.
Now, I found the resistance and temperature chart for the autometer sensor that came with the gauge found here: https://www.autometer.com/sensor_specs
So I idled the car in the garage until oil temp on the gauge read exactly 180F. while it was idling I hooked up my multimeter set to ohms. The black wire on the sensor housing, and the red wire on the wire at the back of the gauge housing.
With the gauge reading 180F, I shut the car off and observed the multimeter in that exact moment.
It read 105.6 ohms.
According to autometer's chart, this would indicate that the oil is at 220F.
This makes no sense. The IR thermometer reads just a hair over 180F.
If the sensor is accurate, then the gauge is not displaying accurately; possibly due to a bad ground in the sandwich plate, maybe I used too much Teflon tape (Autometer said to use Teflon tape, so I did, but they did not specify how much). Which from what I understand, if the ground of the sensor is bad, it would make the gauge read low.
If that's true, then the oil temperature at idle is AT LEAST 220F, and could be SIGNIFICANTLY higher when the gauge goes up.

But, if that is true, then I would have the believe that my engine should be dead. Like dead dead. The oil would have broken down and the motor should have seized. Yet it runs great and has reliably since 2019. Plus the IR thermometer says my oil temps are nominal and within expectations (at idle and immediately after stopping at least, impossible to use the IR on the oil filter while driving lol).

With what I've learned, my assumption is that the sensor ground is likely bad. If the resistance chart is correct, then the gauge should read 220F at idle.
But I also believe that I have established that the sensor is faulty. Even if the ground is bad, it does not explain the wild resistance readings at an assumed temperature.

Over the last few minutes typing this, the engine has been off and cooking down. I can comfortably grasp the oil filter with my entire hand and it does not burn me. The IR thermometer reads about 113F.
The multimeter is reading 145ohms as of typing this, which is still above 195F by Autometer's chart.
That can't be correct...

Eastman51

1) I just did some measuring of temps with an IR thermometer and I believe my thermostat is functioning correctly. There's also no way the engine could have lasted 2 years of heavy abuse if I had installed the thermostat incorrectly, plus I remember it being pretty obvious which it way it was supposed to install.
2) Yea, the car was 100% stock, minus the radio, when I bought it; and basically as original as possible other than obvious maintenance items. Previous owner bought it new, drove it 68k miles, parked it and forgot about it for 15 years; sold it because he didn't want to deal with the pain of restoring it, and because the Mazda dealership told him it needed a new gas tank. The green residue indicating leaks would definitely explain my very very slow loss of coolant over time. I'm sure it wouldn't hurt to get a new radiator, but I will wait on that until I pull the car back out of storage in the fall. It has also worked faithfully for 3 years now.
3) Considering the person that recommended me this setup has no heat issues on a 12A with a turbo slapped on, I think its adequate. Especially with the numbers I'm seeing on my IR Thermometer. I understand that electric fans increase amperage draw and yield no potential power or other benefits over the clutch fan, but there is one thing. Cost. Fan clutches for my Toyota van are $40 a pop, but fan clutches for this thing are about as much as my beater Corolla that had a stuck open thermostat and a "clunk when shifting into 5th on the highway" was. Many many older cars started to use electric fans in the 80s and 90s, and has carried over to nearly every new car since at least 2005. If electric fans were seriously incapable of doing the job, no one would use them. Hell, my 80s Camry has factory electric fan. I think the biggest misconception about efans is that people overestimate the ability of a fan, and then complain about overheating when its obvious they did zero research or set it up improperly. I didn't walk into this blind. I have not seen any issues caused by the increased amp draw thus far. The S4 alt is doing work, plus I also converted 98% of all light bulbs on the car to LED; which drastically reduces amp draw.
4) I have never touched the timing ever. As far as I am aware, the timing is the exact same as it left the factory. I have not checked it either. Car has always ran fine. Whenever it had issues and others jumped to timing, I always said it couldn't be; I've been right every time so far.
5) I changed the coolant in summer 2021 because I pulled the engine for the oil pan and clutch. I filled it with premixed 50/50 Peak Green and bled it thoroughly with the heat on full blast. I replaced the radiator cap in spring 2020 when I did my initial coolant flush and change. I check the rad every once in a while to make sure its topped up, and check the overflow at the same time. Every time I've checked lately, the rad is full but the overflow is low. Probably from the old and likely leaky radiator. I have not discovered any other leaks; as mentioned in my original post, all new hoses and clamps in 2020, and new water pump in spring 2021.
6) My oil pressure gauge has always worked. Reads 30psi at idle, and reads 60psi or higher above 2000rpm. It has always been this way and almost always worked. There was one time that it didn't back in 2019, about 7 days after I bought the car; started it up to take it to the tire shop to get some new tires, the oil pressure gauge worked at start. Got partway down the road and realized the gauge was at 0. Immediately turned off the engine and pulled over, look things over but did not touch anything. Decided to just limp it to the tire shop and deal with it after it had tires. Leaving the tire shop the gauge worked right away, never had an issue since.
I change my oil religiously at 3k miles. I check it nearly every cold start and always top it off when it reads below the top of the hash marks.
7) The other forum is a dedicated group of first gen owners that have helped me successfully diag some issues in the past. While I don't trust them blindly, I do like to at least hear their two cents.

Yea, if my oil temps are accurate and there is an actual (serious) problem in the cooling system, I think my motor would be long dead. Generally I abuse the car pretty hard, almost every chance I get I'm revving it out to 7k in 1st and 2nd, sometimes 3rd. It would be impossible for the engine to survive with any significant issues. Check my recent post above with some updated info, I think I may have tracked down the problem.

Benjamin4456

So I feel obligated to jump in here for one, because I was at least a part of Eastman's "other forums", and also that I disagree with some of the e-fan opinions that were mentioned.

First I think it should be acknowledged that if the coolant temp is staying where it ought to be - which as far as I am aware, it is - then whether it's being cooled by an e-fan or a clutch fan is irrelevant. Being that this is a beehive setup (tall radiator), there is no ducting that we have to worry about the e-fan not properly covering like the factory fmoc shroud. And unless the beehive relies on the air being blown around the engine bay by the clutch fan for a significant portion of its cooling power (which maybe it does, though I wouldn't think so), I don't see how it could be affected if the coolant temps are remaining the same before and after the fan swap (if not improving). If anything it seems like a coincidental issue, and perhaps may be more gauge wiring related due to adding an e-fan than anything. I'll be curious to see how this progresses.



Moving on to me nitpicking (please no one take personal offense):

For context, I suggested this fan as an optional solution to the issue of rising coolant temp at highways speeds paired with the fact that, from what I could gather, his clutch fan was acting stuck and noisy. Clutch fans when locked up at speed become a restriction and will often hinder airflow more than they help, which is why a dead clutch fan can lead to overheating at speed. I know I'm not the only person to have experienced this.

Regarding the controller sensor location, I know people have differing thoughts but here's mine. You want the fan controller to be controlling the coolant temperature "indirectly", whether that's via a push-in radiator probe or a coolant hose tee doesn't matter (and the push-in probes really do work fine). The main thing is that the sensor must be on the radiator side of the thermostat and not the engine side. Without adding a tee coupling to the radiator hose, there is no other location to mount a sensor that fits this description other than a basic push-in probe. The OE choke switch location is on the engine side of the thermostat as is the gauge sensor port. Reason being for the location is that most fan controllers work off a temp delta (usually 10F degrees). If it's measuring engine temp directly, your engine is now swinging from 170F-180F (or whatever you set it to) which is obviously not ideal. Rather the radiator should be experiencing the temp swing and the thermostat controls what the engine sees for coolant flow in order to maintain a constant temperature. I'm sure many folks already understand it, but I see this come up often enough (not necessarily just here) that I feel like it was worth mentioning.

As for the gap between the fan and the radiator, yeah of course, it's not ideal. However, it the cooling system is staying at the correct temp, then why does it matter? Only possible problem I see here is that there may be slightly less airflow through the engine bay at idle, which is not where the oil temp issue is emerging. Also shrouds; there is no reason to add a fan shroud unless you are trying to direct the air somewhere after passing through the radiator, or the engine doesn't stay cool at idle and low speeds. If anything shrouds hurt cooling performance by restricting air flow when you need it most, ie. when you're moving. Clutch fans get around this by freewheeling (as do e-fans to an extent), and well designed shrouds will have air flaps that give restriction free pathways for air to exit when at speed. Unless there are cooling issue at idle and low speeds, I do not see how a fan shroud will help.

Lastly, good ole "e-fans don't give you any horsepower". I have no data to say which is a more significant source of drag while in operation, but what we can say is that e-fans are not running while you're moving at speed (assuming your front end ducting is working properly). Not running means no drag, clutch fans are always creating some drag regardless of what speed you're going (either due to air friction, or added rotational mass). The main benefit of e-fans is that they only run when they have to, and therefore only create drag/load when they have to. Sure a stock 55A alternator might be a bit of a stretch, but if I recall correctly Eastman has full LEDs in the car and an S4 alternator. Whether that was mentioned in this thread I'm not sure, so I could understand that being a concern to anyone not aware.


Anywho... My apologies to anyone if it felt like I was going at them, that was not my intent. Cooling stuff in general just seems to have a lot of confusion around it and it bothers me to keep writing it out. That said, I don't race competitively and just have a simple street car, so please, if someone here knows something I said is way out of whack, let me know. I don't want to spread misinformation either. Now I hope I haven't gotten anyone too riled up.

t_g_farrell

iTrader: (1)

The biggest issue here is that this is a beehive setup and its very sensitive to any variations in the cooling system, since the oil temps can never get lower than the coolant temp. So any deviation like removing a shroud or using a electric fan that can't pull enough or a sticky tstat can be exaggerated in the beehive setup. There is a reason Mazda dropped the beehive in the series 3 (other than there is no way it could ever cool a 13B). The beehive was a bean counters dream, so much cheaper than the FMOC but at a cost, reliability. The beehive never came back after 83 and it shouldn't, marginal cooling at a fraction of the cost! Yeah!

Benjamin4456

Certainly, and I think this is a great argument for why it would be worth getting an accurate coolant temp measurement before proceeding further here. If coolant temps are where they should be, then the issue must lie with the beehive side of things. If they aren't, then we know where to start looking. The OEM gauge and an infrared thermometer give a reasonable estimate, but if the beehive is indeed so picky (I don't have any personal experience with it) then a few degrees might make quite a difference.

On the topic of thermostats, I went through a Stant and two Atkins thermostats before I gave up and bought a Mazda OEM one (gold in color). World of a difference and acts exactly like it was supposed to.

Maxwedge

iTrader: (1)

The beehive was installed on all 12A's in '84 & 85. It was actually used for emissions reasons. Letting the oil and coolant share a common cooler helped bring the engine temp up to operating temp a little faster and cut down on emissions during warm-up.

t_g_farrell

iTrader: (1)

I stand corrected, thought it was only on 81-83 series 2 cars. The reasoning here rings false and sounds like management speak for its cheaper so its better. LOL

Carl

iTrader: (2)

I actually never had any problems racing my spec7 in socal or phoenix with the beehive cooler originally in my car. I did not have any aftermarket temp gauges tho so could only see that the stock gauge stayed very low (like in the picture from the first post above) . I know, based on later experience with an aftermarket gauge, that the stock gauge is not very sensitive to changes in coolant temp. I think by the time I really saw any significant movement in the needle of the stock gauge, the aftermarket coolant temp was up around 220 degF.

Don't forget that the coolant going to the beehive cooler is coming out of the "cold" end of the radiator and as such is significantly cooler than what would be indicated by any gauge on inlet (top) of the radiator. It would be interesting to know what that "cold" temperature typically is. And as was noted above, the beehive oil temperature will track more closely with changes in performance of the coolant radiator.

Also the oil temp gauge could be off. I recently had that problem with my oil temperature gauge. When I tested it with boiling water, it indicated 232 degF, so 20 deg too high. I ended up pulling the sensor and gauge. While my wife was out to lunch with friends I hooked them up in the kitchen, suspending the sensor in corn oil in a pan on the stove. I slowly heated the oil and recorded the sensor resistance, indicated temperature on the gauge, temperature indicated on a separate thermocouple hooked up to a multimeter and temperature measured by an analog candy thermometer. Clearly the calibration of the gauge and sensor were out of sync. To solve the problem I added a 15 ohm resistor in the circuit so that the temperature was accurate around 200 degF (+/- 10-15 deg), which is the most important range for me. Because the relationship between resistance and temperature are not linear, the temperature is off at both higher and lower temperatures. If it is cooler it definitely doesn't make any difference and if it is higher I know I need to shut things down anyway.

Carl

Maxwedge

iTrader: (1)

I'm not sure your thinking here. A beehive cooler costs the same as a fmoc (+- $700 new) but needs more $ in various oil and coolant hoses. It wasn't cheaper in any way for Mazda to switch to the Beehive for the '83-85 12A cars, especially considering the cost to engineer it. They did it purely for emissions regulations, which all auto makers were desperate to meet in the early 80's. And it worked. It kept the oil cool and met the EPA requirements for a few more years.

The S3 13B's (GSL-SE) didn't have to use it because the A/F ratio and emissions could be controlled much better through the use of EFI. That's why we never saw a beehive again after the 12A.... All newer engines had modern EFI.

*EDIT - I just looked at MazdaTrix' website and while the Beehive and the GSL-SE fmoc cost the same, the earlier (S1 & S2) fmoc's listed for $1200 when they were still available. But the S1, S2 and (-SE) S3 fmoc's are almost identical, so I think this price difference is just due to availability. Meaning it didn't cost Mazda any more to manufacture one in '84 as it did in '82, or '80. It just costs more now because they're unobtanium.

Eastman51

From my research on the beehive, it actually pulls hot coolant from the rear iron and pushes it past/through the heater core, then down to the cool side of the radiator and mixed with the cooled coolant from the radiator and drawn back up into the water pump. This is why the beehive works great for emissions. As the coolant rapidly heats up during warm up, that heat is also transferred into the oil; thus the engine warms up faster overall, since oil is an integral part of cooling in these engines. Its design is obviously still able to cool the oil, at least to a certain degree, as cool oil is very important.
I'm always told the beehive should be adequate for my use case, all street and maybe some autox in the future. So if there is any actual problem with oil temps, there is definitely something goofy happening.

Yea, I think my gauge is reading low for some reason. My theory on that so far is that the sensor is not grounding properly.
But more importantly I think the sensor is completely busted. When I check resistance and compare it to the spec sheet, the temperature it thinks it's at is significantly higher than what the gauge reads; but even more critically, the gauge reads way higher than what my IR thermometer reads on the oil filter itself. I've never encountered a problem like this before, which to be fair its my first time playing with sensors and gauges at all, but my assumption is I need a new sensor and to make sure it grounds properly when installed.


I felt confident enough in my data thus far to take it on the trip I mentioned in my original post. 4 hours of highway (2 there, 2 back), and a good 2 hours at least of hard driving in the hills. At every pit stop I jumped out with the IR to check temps, and every single time the temperatures were bang on to where I expected. The oil would obviously be a bit hotter than the coolant after a loop through the hills, but not so much higher I'd be concerned; only about 10-20F. The stock coolant temp gauge never moved once it was warmed up to 180F, no matter how high I was keeping the revs or how long I maintained the speed limit on the highway.
I drove the car again today and it was the same way.
For anyone curious, here's a clip of me using the IR thermometer on the oil filter and rear iron to show the temperature range maintained by the efan at idle. This was taken after returning from the trip.

Eastman51

Update:

I definitely suspect the radiator is causing issues now.
We finally had a warm day and I decided to drive the car to work. Was great this morning while it was still chilly, and it did great on the way home; until I got off the highway that is. You know how we all like to take our cars out to redline, yea if I do that from a dig it starts to run hot. Coolant temps spike to about 195F-200F. Part of the problem was that I guess the fan controller needed to be lowered a few degrees, but its just not enough. I did a few pulls after dropping the fan temp, and the oil temp is still perfect by the IR, but coolant temps are still spiking. My best guess is the radiator, as that was already pointed out to likely not be performing very well.

I am also going to order a new oil temp sensor and try it out.

Carl

iTrader: (2)

Interesting about the direction of coolant flow related to the heater. I do not actually believe that it is possible to flow the direction that you described, due to the pressure differences. I checked the FSM for the second gen (the only version that has a diagram) and the diagram seems to imply the direction of flow that you describe. I believe that it is just incorrectly described on the diagram. I no longer have the heater circuit installed in my car, so I can't test which way it is flowing. Since you have an IR temp gun and have been using it a lot lately ;-) would you mind checking the next time you are using it under the hood. With the engine running, if you check the temperature on either side of the heater (the two copper tubes coming through the firewall) with the heater and fan full-on, the side with the higher temperature will be the inlet and the colder the outlet. Try to measure on the same tube material (i.e rubber and rubber or metal and metal) so that you are comparing oranges to oranges (or apples to apples). You could also measure the temperature of the small tube connecting the heater to the bottom of the radiator and the temperature of the large tube at the bottom of the radiator. If the temperatures are the same, then I believe the source of the water to the heater is the bottom of the radiator and not the iron at the back of the engine.

It is possible that your oil temperature gauge is not properly calibrated to your sender. That was my problem. Kind of a weird problem, but.....

Looking at your radiator performance seems like a good plan.

Good luck.

Carl

Carl

iTrader: (2)

Need to correct my error above. You were correct about the flow of the coolant to the beehive and heater. I checked a friend's street-driven RX7 and the temp going into the heater on the driver side (coming from the beehive was 165 degF and on the passenger side 145 degF. My error was thinking (that is usually what trips me up!) that the water was essentially being sucked out of the engine by the water pump and pushed through the top of the radiator. After looking at a spare water pump and housing, it is clear that it is being sucked out of the bottom of the radiator and pushed through the engine. Oops!

Anyway, probably nobody cared, but incorrect information on the internet drives me nuts, so I didn't want to knowingly be a contributor. :-)

Carl