Mechanics

TOYOTA AVALON THERMOSTAT PROBLEM

1996 Toyota Avalon • 160,000 miles

I believe I have an air pocket in my cooling system. After a 1/2 hour highway drive then at idle the temp gauge goes up to 3/4 from the regular 1/2. I was told it was an air pocket that has to be bled from the cooling system. From looking online I see that Honda's have a beeder but not Toyotas. My engine is the Toyota 1MZ-FE 6-cyl 3.0. I was thinking of getting that special yellow funnel kit that attaches to the radiator neck to get all the air out, will this help? I have sqeezed the upper hose to remove bubbles too. I was thinking I could remove the temp sensor above the thermostat to allow air to bleed out. Should I do this? I have driven over 200 miles with this problem but it hasn't gone away. Please help.
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PCMentor29
November 21, 2012.



No, the system is bled ok from your driving. You have other issues.

Have you changed the thermostat? Is the cooling fans working?

Roy


ASEMaster6371
Nov 21, 2012.
Cooling fan comes on but not when the gauge says but when the engine is hot. That is the gauge could read 3/4 but the fan won't come on. The fan comes on at idle (as usual) after I run at 2500 rpm for a couple minutes. This leads me to believe the gauge is not showing the engine temp but something else. The thermostat is hard to get to so I don't want to replace it. But when starting a cold engine after a few minutes the top radiator hose will get hot like normal when the thermostat opens.

I just now I removed the temp sensor which is above the thermostat. The coolant is at the top. I am going to drive it now to test it. Also I should say I put some stop-leak liquid in the system and this is when the gauge problem began(I should say the problem began when I drained the radiator). I backflushed the heater core for 15 solid minutes with a flush kit because I thought it was clogged. I don't think the system is clogged but your advice is golden to me. I also had drained the radiator before the stop leak so I could put in 4 qts of coolant and the 1/2 qt stopleak. The K& W stopleak I used does not require you to remove the thermostat or drain it out of the system after.

I know you may say to change the thermostat but please bear with me as I learn the hard way. Thanks


Tiny
PCMentor29
Nov 21, 2012.
Sealants are bad news and clog the radiator. Best never to use them as they themselves will cause issues.

You are going to have to change the thermostat. You may not want to but it will be necessary if you want to fix your car.

Roy


ASEMaster6371
Nov 21, 2012.
I just drove it 20 miles and reproduced the Gauge problem. The gauge goes high when after I drive at 55-65 mph and then sit and idle for a few minutes. The reaon I put Stopleak was to seal the radiator hose that would suck air as the engine cooled and leaked vacuum used to draw coolant in from the reservoir. Which would result in having to top off every day. I know the stopleak was a mistake and I am depressed about it but now I have to live with this new problem. A couple days ago I emailed the Stopleak company on how to dissolve the substance in their product. They responded promptly saying just water will dissolve it. I am thinking of backflushing the radiator can you give me some tips for this? How much flow to look for for example. Can you give me the way to test the thermostat in the car? What steps do I take and what to look for? Thanks


Tiny
PCMentor29
Nov 21, 2012.
Water does not dissolve the stop leak, otherwise it would not work.

The thermostat is in the lower hose and you can use a ray gun that will tell you the temp before and after to determine if it is working at the correct temp.

I would consider getting an acid flush on the rad to get that sealer stuff out of the system

Roy


ASEMaster6371
Nov 21, 2012.
Can you tell me the steps for testing with a Temperature gun(I have one) Are these correct? 1) run engine until gauge says middle 2) Run at 2500 rpm then and check temp of lower hose every 15 seconds. (I notice the top hose was cold and then got hot very notcieably shouldn't I temperatur check the top hose?) Okay here's what I will do: Wait till top hose changes to hot then check the lower hose with my temp gun, is this right?I hope you understand I only used the stopleak as the last resort. This engine has three radiator hoses. Top, Bottom and one under the intake manifolds. I reclamped top and bot but to access the third hose you have to remove the intakes, this is beyond my skills.

For an acid flush do I take the radiator to a radiator shop? It has to be out of the car right?

Also, where do I click to add $$ to this question?
Thanks


Tiny
PCMentor29
Nov 21, 2012.
Yes, rad shop and they or you can remove.

Wait till normal operating temp then check the temps with the ray gun. Normal for upper hose to be hot. Lower is the one to concentrate on.
Go back to the first response for donations.

Roy


ASEMaster6371
Nov 21, 2012.
Also, the problem seems to be a flow problem since at hiway speed the temp is normal. Only when I slow to idle does the gauge read hot.
The fans(both of them) were coming on and the reservoir was full so the car was truly overheating at idle. However the fans shut off before the gauge read normal.

I will test the thermostat opening temp after the car cools for a couple hours. I will email the Stopleak company again and ask again about clearing their sealant from the engine. Thanks


Tiny
PCMentor29
Nov 21, 2012.
At the first response it only has Unfollow Flag Ask a Question Auto Parts Car Repair Manual. Previously I would click on Upgrade Question to put more $ in but I don't see that option now.


Tiny
PCMentor29
Nov 21, 2012.
This is the message I sent them: Hi thanks for your quick reply. I flushed the heater core and it seems clean now. I am having trouble now, the engine overheats at idle after a highway drive. This seems to be from an restriction in the cooling system. Can you tell me what will clear the blockage (your product) such as some chemical other than water. Your product won't clear with water as it is made to seal in water. Please help me to understand this.

Thanks Roy,

Pete


Tiny
PCMentor29
Nov 21, 2012.
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