I did a coolant flush and T-stat change on my 92 camry. Before the flush and currently, when i turn the temperature control to the heat position and increase the engine rpm, i hear coolant flow thru the heater core for a few seconds. I thought i may have some trapped air in the system so i just checked the service manual for a bleeding procedure. I could not find a specific bleeding procedure but what i did find was instrutions for installing the T-stat. Apparently there is a jiggle valve in the T-stat that should be positioned a certain way (figures i found this out after the fact). I installed the T-stat without regard to the position of the jiggle valve and i am now wondering if this is preventing the air from bleeding out of the system? Also, is it normal to hear the coolant flow for a few seconds or do i need to remove the T-stat and reinstall in the correct position?
Anyone have any thoughts on this?

Thanks for the help..

It sounds like you ahve air trapped in the cooling system. The thormostat (if it's Toyota OEM) needs to be installed with the jiggle valve between the 11:00 and 1:00 positions, so the hole is at or near the top. Many aftermarket thermostats do not have a jiggle valve. You should still be able to bleed it properly; the jiggle valve at the top just makes it a bit easier. With the car cold, elevate the front of the car slightly. The front of a slopped driveway should be good enough. If a slopped driveway is not available jack up the front of the car slightly or drive the car up on some double stacked 2 X 4's. Now remove the radiatopr cap, turn the heat temperature selector all the way to high with the output on defrost. Now let the car idle like this for at least 45 minutes. Some coolant will burp out and you will lose a bit. After 45 minutes, shut the car, refill the coolant (50/50 mix) a bit in the radiator and refill the oveflow tank. Reinstall the cap and you are done. I would drive it for about 2 days and then check the overflow tank again. You may have to add a bit more coolant. If this procedure doesn't solve your problem, you may have to go back in and reinstall the thermostat in it's proper position. If you have to do that, you will still need to rebleed the cooling system again as I have described.

Mike

Thanks for the reply, i will try the procedure you suggest.
Also, it was an aftermarket thermostat i installed.

Thanks again..

Thanks for the reply, i will try the procedure you suggest.
Also, it was an aftermarket thermostat i installed.

Thanks again..

If it is convenient, I would go back to the place where you purchased the aftermarket thermostat and ask to see another identical one. Check to see if it has a jiggle valve. Chances are it doesn't. This may save you from needlessly removing it and reinstalling it.

Mike

If it is convenient, I would go back to the place where you purchased the aftermarket thermostat and ask to see another identical one. Check to see if it has a jiggle valve. Chances are it doesn't. This may save you from needlessly removing it and reinstalling it.

Mike


Good idea.
I still have the box it came in so it will be easy to find out.

Thanks

As it turns out, the Thermostat I installed did not have the jiggle valve so I did not have to remove it. I did do the air bleed procedure you suggested but I still seem to have air trapped in the system.
It is using a little coolant (1 pint every 500 miles) and I might have a head gasket issue and thought that maybe exhaust gas is getting in the cooling system thus causing air to be trapped.
Maybe I just need to try to bleed again. It does not seem to be affecting the way the car runs and it is not overheating so maybe i will just let it be..

The leak needs to found and repaired. Obviously when you have a leak, more air is being induced in to the system to fill the volume normally taken up by the coolant. The entire system holds 6.7 quarts, so 1 pint every 500 miles means you are loosing 7% of your coolant every 500 miles. You need to find the leak, repair it, and then rebleed the system.

Mike

The leak needs to found and repaired. Obviously when you have a leak, more air is being induced in to the system to fill the volume normally taken up by the coolant. The entire system holds 6.7 quarts, so 1 pint every 500 miles means you are loosing 7% of your coolant every 500 miles. You need to find the leak, repair it, and then rebleed the system.

Mike

I see a head gasket job in my future..:banghead:

Thanks for your help

i would'nt jump to a h/gasket,have you checked the rad cap??
if it does'nt hold the system pressure you could be losing your anti-freeze
through the cap.pressure test the cap

^ I have to agree with inafogg. Don't look for major problems when it could be something simple like a bad radiator cap or leak in a coolant hose. Even a bad/leaking water pump is a lot cheaper than a head gasket repair. If you don't feel comfortable checking these things out yourself, take the car to a professional and have them pressure test the system. They will remove the radiator cap and install a pressure tester on the system and pump up the pressure a bit and look for leaks. Some shops inject a dye in to the cooling system and then let the car run for about 15 minutes and then inspect for leaks under a flourescent light. You may even be able to use the pressure system tester yourself for free at an Autozone, although I'm not sure if that is one of the tools they loan out.

Mike

Thanks for the replies guys.
I agree, pressurize cooling system and check for leaks. I do have a cooling system pressure tester but do not have the adapter for it to fit on toyotas, I will try to locate one. However, car does not have any external leaks that I can see and in another thread, I mention that previous owner overheated car at which time the coolant loss issue started. I determined at that time that the head gasket was probably at fault. It is loosing coolant at such a slow rate that I decided to put off the repair at that time. Also, after bleeding the system as suggested, I could hear that there was air in the system immediately after doing the procedure so I did not remove the air at the time.
If it was a faulty radiator cap, the coolant would most likely be directed back to the overflow reservoir which it is not doing. when the coolant level drops in the radiator it will use the coolant in the overflow tank also so that part of the system seems to be functioning properly.
I am a competent mechanic with many years of experience working on various makes of cars among other things and a head gasket job will not be a big deal to me, just need to find the time to tackle that job. Thanks again for your suggestions.

Keep us informed as to what turns out to be the problem.

Good luck.

Mike

i would'nt jump to a h/gasket,

I think I just confirmed that it is the head gasket. I was checking the coolant in the overflow tank after i shut the car off and saw air bubbles coming from the overflow hose that was submerged in the coolant.
Just ordered a head gasket set along with new head bolts and a timing belt kit complete with idler and tensioner pulleys and water pump.
That should hopefully solve the problem.