Problem installing Thermostat

Hello, i have a 2000 Monte Carlo, with a 3.4 L engine. Engine was taking to long to warm up so decided to install another thermostat. Temp gage very slow moving. I disconnected the thermostat easily except for the lower bolt, took forever to get that thing out with a open in box wrench. The problem is the lower bolt of the thermostat housing. This bolt is nearly impossible to install with the thermostat housing installed first. There is some sort of pipe in the way; i don't know what it's called, but if it wasn't there, i would have finish this job in a hour or so. I tried to install the thermostat first by installing the lower bolt first; afterwards, i install the housing and upper bolt. Had a difficult time getting it to line up properly, which is probably why it leaked badly after starting the engine. Had to start all over! Very aggravated to say the least. Has anyone else experience this problem with installing a thermostat on a 3.4 engine? If so, what is the best way to repair this thing. Also need to know what is the best type of sealent to use. I tried something in a little brown bottle with an Indian head on it. Nothing but a mess, it didn't seal the thermostat properly according to the leak i had. Maybe i didn't let it dry long enough. Next go around, i'm using some kind of blue silcone sealant; It doesn't seem to work either. As soon as i tried to reinstall the housing, that crap fell off from the housing and the engine. Maybe, it is too cold out (20's). I would appreciate any assistance any of you can provide on the best way to install that lower bolt and the best sealant to use. Hope to hear from you soon!

I have not replaced a thermostat on a 3.4l engine...but on the 3.8l engine the thermostat has a rubber gasket on the outer edge, and then a gasket to cover the area the goose neck sets on top of..


so you need 3 parts to do this..sealant is used on the stud threads only, this prevents the fasteners from rusting out.

Thanks for responding! I have completed this job due to research on the internet. I had to remove the crossover pipe to reinstall the lower bolt on the thermostat housing. The job wasn't too bad! I was curious though as to whether or not i could have rotated the engine forward to install the lower bolt. Otherwise, it seemed almost impossible to install that bolt. It took me forever to get it out using an open end wrench because you can only turn it a little at a time due to space restrictions; I put one in my 3.1 (1996 Grand Prix) without removing the crossover pipe but it was a little difficult. The thermostat came with a rubber gasket that goes around the perimeter. I use gasket sealer (something i got at Auto Zone in a little brown bottle with an Indian Chief head on it, nasty stuff but it works, got it all over me:)) on the thermostat housing and on the surface of the engine where the housing goes; i let both dry out overnight. The only leak i found during the first test drive, thus far, is one of those little hoses that connect to the throttle body. I had to replace the clamp with an adjustable one. I hate those GM clamps. All i have to do now is take it for another test drive. It's always nice to have a backup vehicle if case the other breaks down. Take it easy and thanks again!


I have not replaced a thermostat on a 3.4l engine...but on the 3.8l engine the thermostat has a rubber gasket on the outer edge, and then a gasket to cover the area the goose neck sets on top of..


so you need 3 parts to do this..sealant is used on the stud threads only, this prevents the fasteners from rusting out.

that is good you have corrected this. thanks for that info..I find this thermostat replacement on your engine something GM should have designed with the repair tech in mind ...
good luck

FYI,
My problem has been resolved. No leaks and thermostat is working fine. I now have plenty of heat to keep me warm while cruising to and from work, etc. Happy Holidays



that is good you have corrected this. thanks for that info..I find this thermostat replacement on your engine something GM should have designed with the repair tech in mind ...
good luck