Jet-Jock

I searched the archives and read most of the post on thermostats, but I still have questions. I also have the "red" GM/Cheverolet Service Manuals and read the chapter on the coolant system.

The Service Manual does not cover thermostat replacement on VIN P. It does have info on VIN J and in the VIN J section it has three illustrations one titled Coolant Pump and Thermostat Installlation VIN P, another is for the ECT sensor VIN P, and one on VIN P Throttle body and hose bleed. But no where does it give the specific instructions for replacement.

To replace this item what are the correct procedures and what is the correct torque for the two bolts?

I'm assuming that the air duct needs to be removed, and probably some coolant drained. Any idea how much coolant needs to be drained? When I do this I want to make sure every precaution is taken to not get coolant on the Opti.

I had my water pump and Opti replaced about a year ago. On my invoice from Chevy it list a water pump kit (12527739), granted I'm going to call them tomorrow to ask this question but do you think the kit came with a new thermostat?

Just in case I picked up a new stock thermostat today at Chevy (12555290). They mentioned something about the gasket is part of it. I assumed included with the thermostat, but when I opened the box it was just the thermostat. It does have a black rubber type ring that fits all around the circumference of the lip of the thermostat. Is there no other gasket? Sure looks like there is one in the illustrations.

When I examine mine obviously it looks brand new because of the new water pump but it sure doesn't look like there is any gasket, spacing caused by a gasket or any hint of gastket sealing material where the thermostat housing meets the water pump house. It appears like its metal to metal. Is this correct?

It seems kind of silly to me to replace the water pump and not put a new thermostat in or it not be included as part of a kit. But logic doesn't always dictate the path GM takes.

I've had the coolant system flushed right before the water pump went out (obviously a waste of money) so it has fresh fluid. The radiator intake is void of debris. Seems like this year I started seeing a little higher temps then I have in the past when in heavy traffic or waiting at stop lights. At cruise speeds I get what I think are normal temps, or about 193-198, in heavy traffic and stoplights I've seen it as high as 213, but it usually runs 204-208 in those conditions (AC always on in Auto mode).

So I was beginning to wonder if the thermostat wasn't replaced with the water pump and its the original, that would mean its like 11 years old and has over 102K on it, maybe its getting a little lazy and a new one just might perk things up a little bit so it works a little more efficiently.

My understanding though is that the thermostat is there to set the operating temperature for the engines open loop mode as quickly as reasonably possible. To me that means the thermostat is there to let it reach temp then open to allow coolant flow. If it is a 180 model that would mean it opens at 180F so the engine has reached the temp it needs to operate in open loop mode. Keeping the focus with the coolant system, the air flow over the radiator helps regulate the coolant temp along with the aid of fans. Therefore once the thermostat is open its job is over until the temp drops below the 180 mark where it begins to close again. Does that sound about right? If so then my assumption about the function of a thermostat is the set the base engine temp and has little to do with maintaining the engine temps beyond its 180 reference? Correct?

Anyway I'd like to know your thoughts and answers to some of these questions for those who have this model year engine configuration, and have done this before.

Sorry for the long post.

:seeya


[Modified by 93JetJocky, 8:24 PM 11/25/2003]

Strick

When I bought a new AC Delco coolant pump from GM, it came with a new 180 degree thermostat already installed. These thermostats have a rubber ring around the edge of the T-stat and the unit fits into the housing so when the cap is put on it the rubber gasket makes a good seal, and you can't see the seal from the outside. My Helms (92) has a description of installing a thermostat and the torque is 10 N-m or 8 lb-ft.

I changed over to an electric coolant pump and there are many advantages to this. One being you'll never have to worry about drowning the opti from a leaking water pump and you eliminate one possible oil leak. And it works better. :thumbs:

Ramrod92

Man, you pilots are killing me. I'm betting you were looking at page 6B-32, try page 6B-22 (this is from the 92 manual, the 93 I'm sure is the same). Tom's got the right torque values. Who do you fly for? :steering:

Jet-Jock

I'm sorry, I suppose the 92 edition must be different in some way to the 93 edition (ST-364-93-1). 6B-22 - 6B-23 contains the subjects on Electric Cooling Fans (VIN P), Right Side Fan Motor (VIN P), and Fan Shroud (VIN P). Pages 6B-32 - 6B33 contains the sections on Right Side Fan Motor/Blade (VIN J), Fan Shroud (VIN J), and Coolant Pump (VIN J).

Thanks anyway.

tobijohn

Lani,
I've got a 96 so I don't know if it would help you or not but I'd be more than happy to scan and email you the pertinent pages and illustrations for T-stat R&R and "Draining and Filling Cooling System" sections out of my 96 shop manual. Also, as Strick mentioned, other than that black O-ring around the T-stat itself, there is no gasket per se for the housing. Let me know...

Ramrod92

Damn Lani, that's strange. Try taking a look at page 6B-1 and see if they have the pages listed for Thermostat(VIN P). I sure would have thought the 92 and 93 would have been the same. I guess the waterpump change had something to do with it. Do you fly professionaly? :crazy:

Jet-Jock

Yep sure is odd, it's probably something missed when they reviewed the manual for publication. On 6B-6 they tell you about the thermostat ... that it is a pellet type and how it works. But that's it, all other references are to the other engine.

I realize its not a major issue to change this thing, I was mostly concerned about the torque and about how much fluid to drain so as to safely remove the part without drenching the front of the engine with coolant. During my search in the archive I read from one poster who cracked their thermstat housing during installation by not torquing it correctly (too much). It being a cast aluminum part, I just wanted to be careful.

In reference to Strick's post, I confirmed that with the parts depot this morning you are correct it doesn't have a gastket, the rubber seal around the lip is what makes the seal. Not having removed it, I'm guessing its recessed and the thermostat seats down in the recess. I'll just have to be careful and note the position of the old one when it comes out so as to correctly install the new one. I did find the torque specs on page 6B-40.

It just would have been nice to have that documented in the service manual, and to know about any precautions.

Thanks to everyone for your help.

Oh yes, the water pump kit that's just the water pump and a gasket. So they installed the old themostat when the replaced it. One would have thought that at some point the service advisor or mechanic would say hey if we're installing a water pump we should sell the customer a new thermostat. Especially since this old one could be eleven years old. What was that saying again, hmmmm "I tried to think but nothing happened." Yep that's it.

Lastly, yes I use to fly professionally (Continental and Piedmont/US Air), back a few years ago. I'm not currently flying. I don't think the pilots are killing ya, its probably more the nature of the beast at ATC. We just make your job more interesting. especially when the weather is crud or when someone isn't doing what they are suppose to be doing. Are you in the tower, approach or center? Airspace has changed so much in the last decade or so. Well don't want to hijack my own post huh.

Thanks again everyone.
:chevy

Jet-Jock

Hey John thanks. For the moment lets see how things go. But thanks for the offer. Weren't you the one we worked together on solving a wiper problem a while back through email?

If so, how are things going?

Happy Turkey Day!

tobijohn

Yup, that was me...and after new OEM arms, new OEM blades, Bon Ami cleanser, isopropyl alcohol, RainX and a claybar, I'm still having the same problem. All of the above worked for about a day and then the blades started hopping and crashing again. I just very carefully tried Goof Off which contains Xylene and Methyl Carbitol (whatever that is) but haven't had a good long rain yet to test it. Acetone is next on the list....
:confused: :banghead:

You have a great T-Day as well and just let me know if you need that info scanned....
:seeya


[Modified by tobijohn, 7:41 PM 11/26/2003]

Ramrod92

Just kidding on that. Actually 99.9 percent of the pilots I work with are great. Every now and then you will find one that's having a bad day. The percentage of controllers fitting that description is much higher. I work at Memphis Center, but the airspace I work is from just north of BWG to HSV and from CSV west to JKS. Anybody flying through, just ask for Ransome. :seeya