Thermostat project update....and then some.

Well, I started off about 10am this morning replacing my thermostat with the new "enhanced" thermostat from GM. The reason I did this is because last winter I had some issues with running hot or overheating when the temp was below freezing. Per GM's TSB I replaced the thermostat.

Now, I want to thank carbon02 for the pictures of the old and new thermostats. He sent them to me last night and I verified that the part I got in the mail was the new design.

The old thermostat show below has a solid bottom plate.
http://img.photobucket.com/albums/v78/LittleHoov/computer/Oldthermo.jpg
The new thermostat shown below has 4 slots in the bottom plate, apparently to allow better flow under low flow conditions.
http://img.photobucket.com/albums/v78/LittleHoov/computer/Newthermo.jpg

Now lets get on to the project. I started off by jacking up the front end on the right side, to access the block drain. As the tire left the ground, some inner witness told me to grab the wheel at a 6 and 12 position and shake it. I did this and hear a decided "clunk clunk" and theres considerable movement. Keep in mind I just replaced the wheel bearings not a month ago.

I took the wheel off, and attempted to tighten the 3 bolts on the back of the bearing, but none of them even budged, in fact I shattered my 13mm socket in the attempt. This leaves only the axle nut, or simply a trashed bearing. I dont have the axle nut at the house, its being brought later today so that project goes on hold.

Moving on, the radiator drain plug was installed by Satan himself, and I could find no tool known to mortal man that could remove it. So I popped off the lower radiator hose and commenced making a mess.


I caught what coolant I could, but some of it got on the ground, yes thats right Im a polluter, but I live in no mans land, and none of my animals were harmed by it, its all gone now.

Then I installed the flush kit I bought into the heat hose and began flushing through the upper radiator hose, it took all of about 10 seconds for the water to start flowing clear. I tried it with the engine running with the same result. I didnt want to risk waiting for the engine to get hot, because I didnt even know if the water was going through the engine.

I removed the fill tank, and rinsed it out as best I could, it really needed some sort of cleaner to get the Dex-cool residue out of it, but I had nothing.

The lower rad hose clamp is definetely a pain, I got it off fairly quickly though with a pair of channel locks. The heater hose from the thermostat housing actually gave me more trouble, and since the new stat came with a new hose, I finally just cut it off.

The older thermostat came off surprisingly easy, two bolts, and I didnt have to loosen the belt even. What was shocking is that the "old" thermostat was actually the new design. I thought "well crap", but I did notice that at least 2 or 3 of the 4 slots were clogged up with Dex-cool that had hardened..so I thought that might have been the problem.

Before installing the new thermostat, I decided to take GM's engineering a step further and I drilled two small holes in the bottom plate. Might as well let some coolant flow eh?

Reinstalled the new stat, and while doing so, did something that I highly recommend if you are working on the cooling system.

Get regular hose clamps and put them on your cooling lines so that you dont have to mess with those God-forsaken wing-like clamps that GM uses. I didnt have one big enough for the lower rad-hose laying around, but luckily, my dad's farm truck was here, so I popped the hood and robbed a clamp from it until I can get one later. It will definetely save you time and headaches.

Started it up and began adding antifreeze, it had taken a whole gallon before I could blink, then I added some water and it acted like it was full. Purged some air from the system then took it for a little drive.

It runs cooler than it used too according to the gauge, I dont know if thats a good thing or not, it runs between the 1/4 and the 1/2 mark, but not quite as close to halfway as it used too.

I didnt seem to have any issues with air in the system, or none that Ive seen yet, the system seems to be cooling just fine it was 80 degrees outside today.

My only concerns are that my coolant mix may be off, I plan on getting a tester and seeing how it is before winter arrives. Also, if its running cooler than usual in the summer, it may run too cold in the winter. But then again, Im only basing the fact its running cold off the gauge, the actual temp may be just fine. Only way to tell is to hook it up to a diagnostic machine.

Sorry for the long post, but I wanted to share my experiences.

Nice write-up, and thanx for the pics...Great job!

What coolant did you go with....Green or DeathCool?

What did the wheel bearing have to do with thermostat replacement? Or was this just a check that you did while you were working on the car?

Good to hear things worked out. With the new thermostat the temp does run between the 1/4 and half mark. Very rarely gets to the half mark anymore on the 2000 Intrigue that I did a thermostat on.

The coolant drain plug can be turned by using a 3/16" allen wrench right down the center of the drain plug. The drain plug has an o-ring at the end of it, and the idea is to pull back the o-ring out of the groove. It's not threaded, and when your turning wiggle the allen wrench until it starts pulling back. Do NOT pull it all the way out. It's designed to drain straight down in a pan fairly nicely through a port in the radiator, it doesn't drain from around the plug unless you remove it completely.

The plug I believe is ported inside of it to use either a 3/16" allen or a 1/4" ratchet extension. Try to use the allen if you have one.

Thanks LittleHoov for posting your experience. I really appreciate it. I plan to flush my cooling system and replace the thermostat.

One question: what tool do you need for the engine block drain?

The engine block drain uses an allen wrench, I couldnt get the thing to budge personally. I couldnt get the radiator plug out either, so I didnt drain nearly as much coolant as I wouldve liked, but still got quite a bit out.


As for the wheel bearing, I was removing the right side tire for better access to the block drain, and I happened to grab the wheel and shake while it was up in there. Got it fixed....$140 later.

I changed my thermostat and drianed it all before the engine drain bolt was a pain, I striped it but I put in a slighty bigger allen in by pounding that sucker and got it moving.

Green or The ''Dexcool'' im already seeing crap in thier changed 1/07
I assume I got the old design from napa in 2/07.

Intrigue owners don't leave your car unattended in winter warm up it may overheat

In the winter or about 15 degrees or less my damn thermostat gets frozen just like you littlehoov. It could of overheating if left unattended and Id drive it with no heat so awful then it pops opens after thawing I had to use the hazards nuetral off, gassed it in traffic to suck in cold air. And it drive's between the 1/4-1/2 mark only hitting the 1/2 mark on hot long drives with the ac on, but closer to the half.

Well, I am firmly hoping to have no overheating issues this winter. If it gets too cold I might have some other issues though because a quick coolant test showed I was only good for -10. It usually doesnt get that cold here. But ya never know. I think my mixture needs more water.

Ill let you guys know how things go once we get some below freezing weather.

hey guys i'm new here i was wondering something i have a 98 intrigue i was having overheating issues with it. It's a 3.8l i changed the waterpump thermostat and did a rad flush on it it's still overheating. When i drive around the city it will hit the half way mark on the highway sometimes it gets to the 3/4 mark as soon as i turn the heater on full blast it will drop the temperature. The thermostat i bought is a jobber from a parts store do i need to have the GM one? I'm lost on how to fix this. Thanks.

Check to make sure you have a good seal on the radiator cap. You may just want to replace the radiator cap.

Check to make sure you have a good seal on the radiator cap. You may just want to replace the radiator cap.

thanks i'll definetly change that tomorrow do i have to purge the air off the valve on the thermostat before i put on the new cap?