enuttage

I got paid today...and the smiles end there. The bank lines were excrutiatingly long today and my FD was sitting...sitting...sitting...and then in stop and go traffic back to the office. Started it up about 10 minutes later to go grab some fast food, and bam! I'm overheating.

How normal is this? What should I look for as my culprit? Should I even attempt to drive it home in rush hour traffic?

I just got the car yesterday. Ain't that a bitch?

-E

SanJoRX7

First things first...dont' drive it if it's overheating. This can lead to your engine being ruined, and you'll be in for a heap of expenses at that point.

Check your coolant reservoir to see if it's got stuff in it...if it's dry or really low, go get some distilled water and get to adding it. Also, when the car is cold, pop the radiator cap off (make sure to use a rag just in case it's still warm...don't want to get injured) and see what that looks like...oil in it is bad, make sure you see some coolant/water in there.

Are your fans coming on? If not, that could be one problem. When i'm in stop/go traffic I kick on the parking lights to help the fans come on more quickly, probably not a bad idea for you. Your fans might be busted altogether, so check to see that they're working at all.

Is everything stock? What year is your car? Some FD's have an overheating problem, and during the summer I found that my FD did get a bit hot while in traffic, but it never actually overheated. If you're still all stock, and all original, you could have some corrosion and clogging in your radiator that could account for this (it's less efficient and so you get less net cooling effect from it).

More info would be good to help us diagnose this.

skotx

Couple of things you can do. Easiest is to wire up a switch that'll allow you to turn on your fans whenever you want, instead of letting the ECU decide that things are getting too hot. Read about it here. Get a water temp gauge to know when things are starting to heat up.

Next you could get an all aluminum radiator. Fluidyne is a popluar choice since it seems to fit nicely in the stock location. Search the forum for other good choices. You'll want to replace the radiator anyway, especially since you're in Texas.

Other than that, just make sure your coolant is good, and you've got no leaks.

enuttage

Thanks for the info. so far.

You guys definitely need more info. from me.

I'm definitely not driving it hot. I IMMEDIATELY pulled into the first parking lot I could.

Coolant is good thus far (levels are anyway). I'll check the radiator and fans next. I don't know if the fans are coming on or not. I'll try the parking light thing.

I'm not stock, but it is the OEM radiator. Engine/exhaust-wise, I'm running a downpipe and a catback and new vacuum hoses (silicon).

I'm wondering if I can make it home without overheating.

-E

MaxRX7

FDs were not meant to sit and idle, much less be stuck in traffic. They need air to flow through the front into the ducts and pass by the oil coolers and to cool the turbos.

juliof

Remember even though the shop manual says the low speed fans turn on at 221F they really turn on at 230F.I think this is a major cause of FD over heating, you need to install either the miata 207F thermoswitch, or a adjustable temp controller to turn fans on at a lower temp.Allso replace youre thermostat with a new one, and up grade to a larger rad its allso a good idea to check the turbo coolant hoses they swell and can burst at any time.

Nathan Kwok

Most of the '93s will turn the fans on (low speed) around 195F if you turn on the driving lights. Turning on the A/C also turns the fans on low speed, no matter what the temp. With my Fluidyne, low speed is all I ever need to keep temps down, so if I'm stuck in traffic, I just turn on the A/C or driving lights and never see 200.

enuttage

Thanks guys. This is helpful. My father-in-law (the co-owner) just picked it up and took it down to our mechanic (who drives a gen. 2 RX) without incident. He was running the A/C to try and make it duplicate what it did with me. Ironically, I think that kept it cool enough not to overheat.

He's still looking at it/driving it, but I think we'll grab a new thermostat and a Fluidyne radiator ASAP and MAYBE short the relays on the fans and run them into the dash. I don't know if we need to do that with a new thermo. and radiator though. Then again, it'd look cool on the dash .

-E

BrianK

Also keep this in mind....

Your engine was running hot, but within spec, before you parked it. When you park it, even tho the engine is no longer running, it will start to heat up a bit (no coolant being circulated to cool the parts down so the heat starts to seep through everything) So if you were on the verge of overheating, then shut down, then started back up shortly there after, you're likely to be up in the overheating region.

People try to combat this by popping the hood when they park after a hard drive (or a trafficy drive) or doing the fan mod that runs the fans after the egine shuts down (although, with no coolant cuirculating, the same thing will happen).

Seems like the best defense is a lower temperature thermostat.

btw: Does anyone know of any sort of a how-to for replacing the thermostat?

QuIcKSiLvEr

Yeah my car has the same problem.. if i just leave my car to idle for a little while without driving it, the needle starts to move past 1/2 way on the stock temp gauge.. i know it sucks, but it's just a reference point.. it's kinda annoying.. like when buying gas when the gas line is long, my car seems like it's gonna overheat cuz the needle keeps on going up and up.. so i just turn the car on and off, on and off.. ahh.. sucks.. but i see the a/c thing works well, so i use that now..

billyrohm

Yeah dude, rig the switch to turn the fans on and install a water temp gauge, if you turn the fans on before stuff gets too hot it'll work better. It's way easier to keep stuff cool than it is to cool stuff down.

enuttage

Okay, there's a new twist on this now...

After driving the car tonight, it seems that the temperature gauge never actually gets much above horizontal (if at all), but my "add coolant" light keeps coming on and giving me the beeping warning. This is happening intermittantly, with no apparent pattern, although mostly in slow moving, stop and go traffic (this is with the fan on).

All that is fine and well, except that when I check the coolant, it's full.

After a little bit of visual inspection under hood (in the dark), it seems like my radiator is overheating, but the coolant in the actual tank isn't being used to cool anything down.

Then again, I don't REALLY know if anything is truly overheating because the temp. gauge isn't indicating that's the case.

Anyone else have this problem?

-E

And BTW, the plastic coolant separator has been removed...don't know if that's affecting anything or not.

Mahjik

iTrader: (1)

Sounds like a failed O-Ring. I had the same symtoms which equaled a new/rebuilt motor.

enuttage

Ouch!

Now the only question at hand is whether the guy who sold it to us knew all along.

It's about time (mileage-wise) for a rebuild, but we were hoping to get 10K or so out of it so we could work on some other stuff.

Alas.

Well, it goes into a local rotary specialist for a look over on Monday, so we'll see what the verdict is.

-E

djantlive

If you have plenty of coolant and the coolant light is coming on, why would that be an oring failure? An oil ring failure causes coolant loss due to it getting burnt by the engine. I think it's probably something else. Have a rotary specialist check it out ASAP and don't drive it around anymore until it's fixed. Let us know what happens. Good luck!

Mahjik

iTrader: (1)

djantlive, I'm no rotary mechanic, but this is exactly what my car did. The coolant was never getting used by the engine. There were no leaks, and the levels were fine.

I noticed that the coolant light/alarm began to come on whenever the car would sit still while running. So, in cases of getting stuck in stop & go traffic, or getting some fast food, things like that, the coolant light/alarm would be going off.

I took the car back to the Mazduh dealership where I bought it and they told me it was normal. They said to open up the filler neck while the car was cold to allow it to re-pressurize. I took it back to them 3 times for this and they kept saying it was normal.

Finally took it to another Mazduz dealer who found the root of the problem. After a new engine, everything has been fine.

enuttage,

I'm not saying you have the same problem, but it's exactly what happened to me when I purchased my FD. The fact that you just purchased it, says to me that the owner knew it needed a rebuild and unloaded it.

juliof

How many miles did the engine have when it failed?

BrianK

Just so we're on the same page, you are aware that the stock temp gauge stays in the center until somewhere around 220 degrees, correct?

where are you checking the coolant? in the overflow tank or at the filler neck?
... curious... how did you determine that? and What does "radiator overheating" mean? Do you mean heat soak or something else?

back to point1... Do you know what your coolant/water mixture is? If you're running 100% water, the water could be boiling and making an air pocket around the coolant sensor - giving you the low coolant warning - all while the temp gauge still reads in the center. If there's a leak in your coolant system, this is even more likely (boiling coolant, that is - because water boils at a lower temperature when not under pressure).

Do the typical checks... check for leaks, check the coolant level (at the filler neck), check the overflow tank (is it overly full? - sign of pressure leak in coolant system).

Problem areas in the 7's cooling system: radiator end tanks, coolant -> turbo hose, AST (Air Separator Tank - I think you said yours was removed).... Checking these is a PITA, but necessary. You'll have to remove stuff in both cases to see what you're looking for. If you see any sign of coolant on the outside of your radiator, that's your problem (this is what happened to me).

Also keep in mind that the AST is there to remove air from the system. If yours is gone you could be experiencing exactly what it is that the AST prevents (tho, it would be pretty unusual, as most people have pretty good luck with removing the thing).

Mahjik

iTrader: (1)

I purchased mine about 4 years ago with around 42k miles on it. By the time I had the run-around with the original Mazduh dealership 3 times and then the next dealership it was close to 50k when the engine was replaced.

enuttage

Very hard to say what's going on with the car.

It ran like a charm for a ~30 mile round trip out to the inlaws place.

BrianK...to answer a few of your questions that I can answer.

1. Yep. I'm aware of the temp. gauge reading only midway at 220 degrees.

2. I was checking the coolant at both locations.

3. I was most likely mistaken about the radiator "problem". It was making the obligatory hissing noises that coolant boil-off makes when a car overheats, but I don't think it was out of the ordinary. I don't even know what heat soak is to be honest with you. I'm sure I'll find out soon enough hanging around here.

4. I am not running 100% water. I don't know what the mix is though.

5. Per advice given here and just a general need to get the freshly-purchased car checked out, I'll be running it by a rotary specialist Monday. I should know by end of day what the problem might be.

It'll be interesting to find out what, if anything, is wrong with the car. These guys have worked on this very car in the past, so they've seen it before. Hopefully, it's something as simple as a bad sensor or the thermostat. If not, well...we had planned to pull the engine and rebuild it anyway...so it'll just happen earlier than expected.

-E

enuttage

Guess who gets the prize for this one?

Mahjik!

It really sucks that you were right, but you were. Sure enough, my O-ring is shot. Ah, well, it's nice to know that the guy who sold it to us had no idea .

Moving on, looks like I'll be cutting into the bank account for an extra $3800 or so.

Thanks for the troubleshooting help guys. Hopefully this'll be the end of my overheating problems for awhile.

-E

Mahjik

iTrader: (1)

Sorry enuttage,

I would have rather been wrong.

You're almost in the same boat as I was when I purchased my FD. You have a leg up though as you found this place, I didn't know anything and let Mazduh charge me about 9k for the job.

At least here you'll be able to find a good place for a rebuild and save yourself about 4k. Good luck!

SPOautos

I know this is kinda old but I followed a link from another post to this one and felt the need to thow some info in.....

If your motor is eating coolant you should be getting white smoke out the tail pipe while driving. You coolant is getting combusted and should show as white exhaust. I'm not talking just about on startup either, if its bad enough to overheat you car it should smoke white all the time.

If you want to perform a test go to the parts store and get a coolant system pressure tester. It replaces your cap you pressurize the system with it then let it sit overnight. If it looses pressure you know thier is either a leak in a hose or its going into the motor.

You can also pull the plugs and see if they have coolant on them.

Later,
STEPHEN

Mahjik

iTrader: (1)

Stephen,

That's the problem, the engine isn't "eating coolant". White smoke doesn't shoot out the exhaust while it's driving at all.

The only symtoms I had were the coolant alarm and one time I saw some smoke from underneath the car. I never saw exactly where it was coming from (it was about 4 years ago so I can't remember everything).

In his case, he isn't seeing coolant dripping and he isn't seeing the car suck down too much coolant. I know since I've been there.

SPOautos

If thats the case I would suspect something besides the motor. I would jack up the car drop the black belly cover down so you can see everything better and run a compression test on the cooling system overnight. If there is a leak it sould show when the system is pressurized.

I wouldnt replace the engine untill I'd exhausted every alternative. I also wouldnt trust a dealership since most do not know how to CORRECTLY work on 3rd Gens. The dealers answer to everything is replace the motor. When they replace the motor they also replace 2 water pump gaskets and reattach all cooling hoses. If a problem went away after the new motor was installed one of these items could have been the real cause.

I've talked to a guy one time in FL that had his motor replaced at the dealership and afterward it still ran the same as before. He drove to Pettit Racing (which is what he should have done first) and they replaced a $ .20 vacume hose and charged him nothing for it. The dealerships just dont know what to look for. Thier answer to what they dont know or understand is replace the motor. Thats one reason our cars have such a bad reputation. I had to agrue with my local dealership that they imported a 95 rx7!!!!!!


I'm not saying its definatly not a oring failure I'm just giving advice and alternatives.

Have they system flushed, maybe the radiator is gunked up and slowing down the coolant flow.

There are alot of things that can cause the engine to run hot.

If the temp never moves up you might also want to test the coolant level sensor. If it comes uppluged or has a short the buzzer/light will come on.

Anyway, I'd check stuff before replacing the motor

Good Luck,