red_blast

Ok here is the scoop. My 85 13b is giving me trouble with running too hot. When I bought it, an electric fan was already installed and a stock fan won't fit in the engine bay, so I can't replace it. It is running about 3/4s hot on the temp gauge. Even after replacing the thermostat, coolant sensor, gaskets, rad cap, water pump, and flushing the radiator, the temp hasn't gone done. One factor to consider is that when I bought the car the orginal coolant sensor was still entact in the block but had somehow gotten misthreaded in and is stuck, so the guy I bought it from left that sensor where it was and relocated a new one in the neck of the water pump. The new coolant sensor is located just before where the thermostat is. So basically the coolant sensor is reading the temp before the thermostat opens. Is it reading so hot because its reading the temp before, instead of after the thermostat? Could the temp be fine in the block and I just don't know it? Should I attempt to get the original sensor out of the block? What do you all think?

clashkpr28

see if your alt. belt is snug, if its not, then that means it slips and doesnt run the water pump all the time... readjusting it might be of some help

rb26powered

What CFM is your fan rated at? You'll need at least 2100CFM or higher. I'm running a flexalite 14" electric fan.

red_blast

the belts are fine. i checked them when i replaced the water pump.

Rx-7Doctor

iTrader: (13)

Even thoug it is located before the t-stat, the temp will go down when it opens. The thing is is , was the correct temp switch put back in? Also as the other post stated the fan needs to
be aleast 2100cfm and flexlite recommends their black max which is rated at 2800 cfm.
Even though you flushed the radiator, it does not mean that it is flowing correctly, the runners could be blocked, have a radiator shop check this. What temp t-stat are you running and what mix coolant? Also could have shop scan temp with infra red to verify the
temp versus gauge. rx7doctor

Hades12

Might want to bite the bullet and replace the Rad. What temp T-Stat did you put in?

Crit wrote a novel when the Sender thing happened and everyone agreed that it should be left in until the engine needs a rebuild.

red_blast

as far as the fan goes... i asked the previous owner if he remembered what the exact fan was that he installed. and he said it was from advance auto, but he wasn't 100% sure which one it was. he thinks its the Hayden 3700... http://www.partsamerica.com/SelectPa...versal+Type%29

Rx-7Doctor

iTrader: (13)

Forgot to ask, is it at 3/4 at idle or down the highway? Check with the local autoparts store
as far as the cfm on a 3700 hayden fan. Check for debri infront of the rad, especially if you have a/c, the condenser traps alot of debri and hinders the cooling. Do you have the lower
engine tray installed that covers the oil pan? rx7doctor

red_blast

it doesn't matter if its in the driveway or on the road, its pretty much stays at 3/4s.

Rx7carl

Even on the highway? Then it aint a fan problem. Your cooling system isint throwing off enough heat. Double check the accuacy of your gauge before you freak out and spend more money.

red_blast

Thanks Carl, I will. I am planning in the back of my head to replace the pulley set up, put a stock fan back in and replace the radiator, if the little things I try don't work.

--Lauren

813KR$

Stay away from the stock fan! Get the lower temp thermostat, you probably got the higher temp one. Usually when you buy the thermostat they will ask you what temp thermostat you want. With you temp staying at a steady 3/4 sounds like your cooling system is working correctly. I would assume if it wasnt the harder you run your engine the hotter it should get if their was a cooling system problem?

red_blast

got the under-drive pulleys off this weekend. what's left: radiator and fan replacement.

red_blast

Ok this weekend I am replacing the radiator. IF this doesn't solve my problems what do you guys think it is? The fan? Coolant seals? (its not burning off white smoke though.) I am really stumped b/c I don't know what else it could be. Input is greatly appreciated. Thanks!

--Lauren

LongDuck

The underdrive pulley's that you removed would certainly cause a slightly higher engine temperature, but primarily at extended idle conditions - this is due to the lower rotating RPM of the waterpump being driven by those pulleys. When the car is underway, the fan (E or stock) isn't pulling air through the radiator - it is being pushed from the front by aerodynamics. Since you state that your 3/4 heat issue is all the time (highway and driveway), then it's likely a bad radiator core that's not shedding heat properly.

This all assumes that you're running the right mix of 50/50 water/antifreeze. Antifreeze not only lowers the freezing temperature, but also raises the boiling point, so you should be running AF for ALUMINUM engine blocks all the time.

A radiator replacement is about the best first thing that you can do when you have overheating. After that, get a MAZDA Factory thermostat with the 'jiggle-pin' and install with the pin at the top - this is cheap insurance that your tstat is opening correctly and isn't the root of the problem. A new tstat is $12 from Mazda, but a radiator is about $250. I have had my stock radiator (84SE) rodded out once and that fixed the overheating problem that I had in the AZ summertime (120d F and blacktop in the city).

Other things to have done - flush the coolant system, block and all. Even if you replace the radiator, the block will have condensed crap in it that can RE-block a new radiator and you'll be back where you started. Remove the block drain below the Oil Filler Cap on the center housing and run the hose through the waterpump outlet after you've removed the tstat. You'll be surprised how muddy that block coolant will be. Let the hose run until the water is crystal clear.

Good luck, this shouldn't be too hard to troubleshoot, and besides, as the weather gets cooler and cooler, it poses less risk to engine damage. Some people love a hot radiator in the winter when they're running their heater! My 84SE has no heater core or feed piping at all, so I just put on a jacket or sweater on those cold (50d F) mornings here in Arizona. HTH,

ranger306ci

Here is something to think about. Is your OMP working? I was taking to a mazda race mechanic yesterday about OMP's, and he said the first thing that you would notice if the oil was not being injected would be higher coolant and oil temperatures.
since this has not happened to me(knock on wood) I can only pass this on as a "he said" kinda thing. But he does work on them year around.................

85rotarypower

What?????? The OMP doesn't do any kind of cooling. I don't get how a malfunctioning OMP would increase engine temps.

LongDuck

Increased friction from poor lubrication results in increased engine temperatures, carried out through oil (2/3) and antifreeze (1/3) cooling systems.

Makes sense. Something to look into.

Tom

Maybe buy a bottle of 2 cycle oil and run pre-mix and see what happens to the temps. Can't hurt.

79+80+84_rx-7

take a pressure washer or water hose, or the high pressure hose are self car wash, and spray the **** out of your oil cooler and radiator....... check for bent fins....... take some engine degreaser to them if you need too....

Later... Andrew

rxseven07

hey i dont... and my car runs at 210F, should i put it back on?

Rx7carl

Yes, its vital for engine cooling.

sgieldon

Hey Ranger;
2 weeks ago, I'm driving down the freeway @ 80 and started to smell something like it was getting Hot. Looked at my Nordskog Gauges and sure enough the Temp had gone from 182 to 195.
When I run her above 110mph thats about normal temps w/oil temp @ 175.

Sooo I pull over and check where the smell comes from. Scratch my *** no where to be found.
As I'm checking for leaks or anything that might have caused the rise in Temps???
Sure enough the RB Holley Setup OMP Rod Had become Disconected.
Reconected the Rod and used a ZipTie for Insurance.
When I race I use Both the OMP and Pre-Mix Castrol 2 Cycle Oil.
The last thing I want to do is Blow up a Pineapple Racing $4,500 Motor.

(I'm sure that this is not his problem.)

But just wanted to make a point that with no Lube on the Seals will make the Engine Temps go up alittle.
Speaking from a personal experience!!!!!
sgieldon
steve

rxseven07

damn... looks like im going to have to put that pan back on..

FDNewbie

iTrader: (10)

Hey Lauren,

I had the same prob you were having, but my FB (84 GSL) would actually overheat occassionally. I did all the usual stuff I could think of (new radiator, new fan, new t-stat, new water pump, etc) and nothing worked. I finally gave up and took it to a shop. I had an autozone generic electrical fan, and they said it wasn't pulling enough CFMs to cool properly, and since I still had the stock fan & shroud, I just got a new fan clutch and put that back on. That def. helped, so I dunno why ppl are saying to stay away from the stock fan.

They also checked the radiator temps at various locations in the radiator via infra-red to ensure there was no variation in the temps, and thus a possible restriction in the coolant system flow. That came back negative. They found that some of the lines running to the oil cooler were leaking pretty badly tho, and replaced those, and I guess that helped since I'm getting more efficient cooling of the oil. The oil cooler itself leaks a bit, but that's prob. just the seal, and I don't think it's worth the $$ to fix at this point...so I just monitor the oil levels often, and add as necessary.

The funny thing is, my FB now has temps that are pretty much dead center, and sometimes even a bit lower than the middle mark...but in the mornings, when I start her up, she'll almost overheat within a few min (I mean WAYYY over the H mark), then come back down later. I think the T-stat might not be working right (mita gotten the wrong one), and also the antifreeze injection (not sure if yours has it, mine does) is something I wanna give a look to as well...since that plays a role @ startup.

Sorry I don't exactly have answers for you, but at least you're not alone in this problem. I'm takin her back to the shop on Monday for them to check it out, see if they can figure out why she runs so hot in the mornings (sounds to me like it's simply a case of coolant coming in too late into the game).