Thermostat replacement, how do I do it? - Page 5 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat

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Old 12-02-2005, 01:27 PM   #41
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Temperature variation could be caused by air trapped in the system. You may not have bled all of the air out.

First, check the level of coolant in the radiator when the engine is cold. It should be all the way to the top under the cap. With the cap off, pump the top radiator hose by squeezing and releasing while watching the coolant level at the radiator cap opening. You should see the coolant rise and fall instantly as you squeeze and release. You can feel and hear the difference between a hose full of air and one full of coolant. When you have expelled all the air you can between the cap opening and the top of the thermostat and have filled the radiator all the way, replace the cap. Start the car, bring it to temperature and bleed at the goosemeck again to see if you can get some more air out. If you have a lot of air in the system, it may take several tries with the bleeder to remove it all. If you get bubbles or gurgles or "spits" when you open the bleed valve, that is air being expelled.

You almost certainly trapped some air in the top of the engine by installing the new thermostat over an air pocket. That is the reason for filling the engine with coolant at the thermostat hole. That way, coolant displaces air at the top of the engine under the thermostat. If you have a little bleed hole in the thermostat flange, it further reduces the possibility of air trapped around the thermostat.

[edit: If you find the rad full to the top when you open it cold, the top hose is full of coolant, and you get nothing but coolant when you open the bleeder repeatedly, then air is NOT the problem.]
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Old 05-22-2006, 03:32 AM   #42
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i replaced the thermostat following the directions from this great thread(very useful) and have continued to bleep from the screw probably 7 times or so, still getting fluid. i did not drill a hole in the flange. my water pump is less than 5 months old.

after i got the water pump replaced the engine would continue to get hotter than usual but not in the red, about 3/4 on the hottest. now after replacing the thermostat the temp still shows getting near 3/4.

any suggestions?

btw, this website is freakn awesome
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Old 05-22-2006, 08:41 AM   #43

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Hi, welcome..

In the future please start off a fresh thread and link to an old thread... helps keep things a little tidier and you won't get love mail from Moderators.

Run the car for a few days/week and try bleeding in a week if the problem hasn't settled down. Our gauges are known to be a little inaccurate, however your temp should settle in a little lower than it'* previous "normal" range. Most likely you have an air pocket that is slightly elevating your temps.

I have put my car on ramps, or jacked the front up to try and clear air pockets before...sometimes they are stubborn. It'll clear though. Hang in and ensure you stay out of the red.
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Old 05-29-2006, 02:46 PM   #44
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When replacing the t-stat, do you ever use adhesive between the paper gasket? There is no mention of it in these post, but I thought I would ask anyway.

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Old 05-29-2006, 03:11 PM   #45
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base1001--please start a new topic. This thread is quite old. Thanks, and welcome!
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