Overheating/coolant problem
 

Sorry if this has been covered before. I have been moving around and have not been at a PC in a while.

Problem:

Coolant light seems to be randomly going off. It went off once and filled the engine coolant. THen it kept going off and seems to have leaked a lot of the coolant out. I then filled it again and the problem seemed to stop. Then a new problem started

Now it seems that I am overheating. It happens erratically. The car will start fine and get to about 1/2 on the heat gage. It will sit there for a while and every thing will be fine. Then suddenly it will jump to red in a matter of about 15 seconds. Sometimes it will get to about 80% on the gage and come right back down. Today it actually hit red I pulled over while this was happening and a hose that connects to the top of the AST I believe came off and was spewing steam. I cooled the engine. Put the hose back in place. Filled the coolant again. Then Drove home about 1/2 mile away. By the time I got home it was about 85% hot again.
I can't seem to keep it stable. There is no sign of any major leaks and the coolant seems to be staying. The oil is fine. What could be causeing this erratic nature?
Yesturday I drove about 3 hours with the heat jumping between 45% and 75% with no real problem. Yet this is still unusual because up untile 3 days ago It never broke 45%.

Thanks.

The fact that the temp keeps fluctuating so erratically seems to indicate a thermostat problem. The manual details how to test it. (In short, the thermostat should start opening between 80.5 and 83.5degC, and be fully open at 95degC. Opening travel is 8-10mm.)
However, I don't know if that would explain your coolant light going off, unless you were losing coolant then already. Assuming these are the only symptoms, make that the rad cap (with a spring valve) is not installed on the AST - the manual is mis-labeled on page E2.

Change the thermostat, flush the sytem and refill, then see where you are at..

Flushed the coolant system. No leaks.

Just drove it. Started out at about 50%on the heat gage then crept up to about 90% in about 15 seconds, then it drops to 60% for a couple of secounds then it is at 90% again and I shut it off.

I open the hood and in the AST I can hear steam hissing. So I know that it is getting hot.

What else do I do?

3rd gen by the way.

did you change the thermo?

No. Do you really think that the Thermo could be causing this problem. The car really is overheating it is not just something wrong with the gage. Am I missing something. Please fill me in. Thanks.

I mean it is pretty quick that is goes up, but it doesnt hurt to change the Thermo, its a lot easier to change then a temp guage... When I go threw something like this I try to change the probable parts that are cheaper first, you can get lucky...

BY the way, what water temp gauge are you going by? just the stock one right?

Yes I am going by the stock one. Where is the thermo located and how exactly do I change it? and can I pick one up at a Pep Boys or something?

Thanks.

What else do you think it could be? I mean if I leave the car power on but not running the fans run to cool it down. Don't know if that would matter.

Well i heard the sending unit for the stock gauge sucks, but I dont know much about it. Thermo is right behind the filler neck thats on the engine, really easy to replace. I dont know if you can get it at Pep Boys, because I havent been in the states for quite some time. But I would imagine they would have it..

So your saying if you turn off the motor, but leave the key on the fans arent running when the gauge says its really hot?

I am saying that the fans are running, but only if I leave the keys in the ignition giving the car power. If I just take them out, the fans don't stay on. Is this normal? It is really pissing me off and I am afriad that I have already done seriouse damage to my engine. Thanks. What else should I look for if it is the thermos?

Yeah thats normal, when you take the key out. Power is cut to the fans...

If it is the thermo then your all good, after you change it. Do you need more info on wher it is? is that what your asking?

yep, I need to know how to change it. Thanks

First get the right thermo. You have the air pump right? Before you take anything off, check your tension on your belt running to the water pump and alternator, and see how it feels, remember that so when you put it back on. Now you will need to loosen the Alternator belt, just to the right of the alternator the is 2 bolts this is too hard to explain with out pictures, but I think you can figure it out. Then I dont know if you can get to the most bottom bolt for the filler neck with the stock pulley for the water pump on not there, so see if you can, and if you cant, take off the 4 bolts and pull the water pump pulley, and then work on the filler neck attached to the motor. Anyway there are 3 bolts that hold on the filler neck, un bolt them I think they are #10 wrench size metric I think for you guys too, probably easier to use the socket if you got it. And bolt them all, WAIT before you unbolt, unclip the sensor wire, you dont want to break that, its on the filler neck the little black circle with a wire coming out of it, trace it back, right around the alternator there should be a clip, so unclip that. Now finish taking out the bolts on the filler neck and pull it off. You will see the thermo right in front of you, probably still stuck to the engine too. OK THIS IS VERY IMPORTANT, when you put the new one in there is a little hole, with probably a little tiny dick lookin thing, that goes towards the highest spot on the engine or hole possible, thats where small amounts of air can escape.. Make sure it all seated properly, and re assemble everything. Dont forget to hook-up the sensor wire, make sure you clip it again, otherwise you get the the BEEEEEEEEEEEEEE noise. Ok now put the pulley for the water pump back on, and hook-up the belts, now the belts tension is on you... Just do it the same as when you took it off. The tension is too hard to explain, is should move when you squeeze them together, but just a little...

My writing is sometimes un-clear so please let me know if you have questions..

Jason

thanks I think that I might try this in 2 days when I have a good amount of free time. Thanks again. I will tell you how it went.

No problem.. I hope it all works out for ya..

I could not really follow your directions. I think I understand but I am not sure. I started taking things apart yesturday and I started to get confused. I think that I am just unsure exactly what to do.
Perhaps you could give me some pics or a step by step break down. Thanks alot.

ok let me get some pictures and I will get back to you today....

Newbie here... I think I'm having the same problem with an 86. I don't seem to have any leaks, but within a mile the car is severely overheating and blowing steam out the overflow tank. The thing overheats SO quickly that it acts like it isn't flowing a bit of coolant. If I remove the radiator cap with the engine running , though, I can see the coolant flowing across the top tank of the radiator and down into the tubes, so I know I've got flow. First things were to check the obvious... no leaks, no damage to the radiator, fan, etc. The lower hose is not sucking shut as the engine runs.
After checking the basics, I removed the thermostat to insure that it wasn't stuck shut. Ran the engine that way for a day - made no difference whatsoever. Next reinstalled the t-stat and replaced the water pump (I wanted to remove the old one to check it, and since I was that far into it I put a new one on). Again no difference.
Yesterday I replaced the radiator caps - should this car have one cap or two? I have one on the fill neck right above the thermostat and one on the radiator itself. One was a pressure cap and one was just a plain cap with no spring-loaded section. I replaced them both with new 13 psi pressure caps. Still have the exact same problem - the car quickly overheats and blows steam out the overflow. If it was a piston engine I'd suspect a bad head gasket was pressurizing the cooling system. Is there a way the same thing can happen with the rotary engine? I'm out of ideas...

Pull the pressure cap of the themostat housing and put the flat one back on. Its designed that way.

A blown water seal or warped rotor housing could cause your problem. Its the equivalent of blowing a head gasket or cracking a head. While you have the filler cap off the thermostat hosuing, start the engine and see if it spits coolant out. If so, engine= toast. The only way to fix it is to tear it down.

BTW, I had both a 78 and 79 Trans Am. One of my more favorite cars :)

Thanks for the quick response, Felix. You have nice taste in automobiles!
Yes, with the cap off of the t-stat neck it spits out nice slugs of coolant. :( Doesn't sound like fun....

I'd look for another engine, ones that have been overheated tend to warp the shit out of the housings, and new housings ain't cheap. :(

sounds like a lot of you guys have air pockets and dont know how to get them out. ok, fill up the radiator as much as you can with the car cold, then start the car. level should drop. then add more coolant till it keeps overflowing. replace cap. wait. see what happens.

are your fans coming on?