Write-Up: Thermostat Installation

Distilled water has no minerals that can contribute to corrosion and helps provide proper Ph balance in an Aluminum engine.
Probably overkill and just being ANAL, but it only costs less than a buck.

thx

Not overkill Rick - distilled water is cheap and you should use it whenever possible in the cooling system.

Rickw wrote:

Then drain and flush again with fresh water until I don't see any more orange from the Dexcool.

I had previously been using both the rubber seal and flat gasket for the thermostat, but this time i cleaned the old gasket off both surfaces and just used the "O-ring" seal, filled system with new coolant and distilled water(50/50 mix).
No leak from thermostat housing using just O-Ring.

Glad to hear it!
I've checked my water outlet a few times since I used only the O-ring, and it's still tight, too.

You're still using Dex-Cool?

Stupid question and I think I already know the answer.... Is the stat in my 1997 Riv the same as the one in my 2000 Regal? Judging by the housing and seeing that this housing has a gasket on it (rather than just an o-ring around the stat) I want to say it isn't. Just trying to save $$ and have an extra 180* stat laying around from the Regal...

Rick,
Just call the parts store and ask if they are the same P/N.
I thought all the 3800's were the same but I'm not 100% sure.

The thermostat is the same, but some used gaskets and some used Orings. Still not sure if you can interchange them, but the tstat is the same.

I don't know if it helps anyone, but my '99 only has the o-ring as a seal. No paper gasket.

Have we found an example of a Riviera without a place for the O-ring? It would seem they should all use both the O-ring and paper gasket, but maybe some mechanics have taken the liberty to not replace the gasket because they assume the o-ring is enough.

As far as I can tell they all can use either or, but I don't want to be the one who says it as writ...

I prefer the O-ring, so much easier than scraping off old gasket material!!

I've always used both. Never had to scrape the gasket, but I don't use any RTV, either.

All that is necessary is the "o-ring" type seal. You can add the paper gasket but it is not absolutely needed.
Where as you cannot use the paper gasket alone because the thermostat will not seal properly internally. It will allow coolant to bypass the thermostat in the housing.

Wonder why did GM put both gasket and O-ring on mine? I'm pretty certain at 25k miles, it was the original set-up.

Could have been original that way.
But now if you look at the exploded view on the dealerships parts catalog it show's the O-Ring as the primary seal.
There is an asterisk and footnote regarding the paper gasket as not needed, yet it is still available to purchase anywhere.
My guess is that the paper gasket would be helpful if you had an uneven surface or slight warpage of the housing and needed to seal it without replacing the housing or resurfacing the LIM.

Good to know, Rick. I haven't swapped my t-stat in a long time, but I may save the $2 and try it without the gasket next time around. Or, I might go ahead and spend the extra $2 - it seems to have worked great for the life of the car!

Well for what it's worth I was using both also until just recently when i flushed my system and changed thermostat as PM.
I had both gaskets on hand but decided I'd only use the rubber O-Ring and it works fine, no leaks and it just saves from having to do one more thing (clean gasket surface) and buy an additional gasket.

If I remember correctly, my '99 service manuals don't even mention one thing about a paper thermostat housing gasket on our engine. Just the o-ring thermostat seal.

I agree, if you really don't need it (paper), don't put one on.

As far as I know, mine had never been apart until I took it apart a few months ago for the big weekend job - (aluminum LIM gaskets, etc. most of what's engine related in my sig).

Cheers

I've only ever assembled them with O-ring only, no gasket, and never had a leak.

You guys were dead on. Existing setup had an O-ring and a paper gasket. I scraped the gasket off the housing and install the new stat with a new O-ring. No leaks and now the car is running cooler.

Thanks for the discussion fellas. It's good to know I wasn't the only one scratching my head when I looked at the housing.

Could someone take a pic of where the thermostat is located?

if your facing the engine you will see a black rubber hose on your right. follow it to where it conects to the engine. below it is the thermo............

ps. if its difficult to find look for the flux capacitor. its above it

robotennis61 wrote:

ps. if its difficult to find look for the flux capacitor. its above it

We have Flux capacitors' in our riv's? WTF BBQ..... I'm taking mine out and selling it

steve s wrote:

Could someone take a pic of where the thermostat is located?

It's under the thermostat housing, which is also where the upper radiator hose connects to the engine.

question....do you do this procedure with the car cold???? and does that prevent losing coolant..or are you going to loose coolant regardless?