changing a thermostat.

i have an 88 park and i want to change the thermostat. my check engine light has been on since i had the car, and i did the paperclip test and it showed a reading of coolant or thermostat along those lines, so i figure the thermostat is stuck open or broken because i don't get heat at all, but the air conditioner works fine. i already have the new thermostat and its gasket, and was just wondering the steps to changing it. do i have to make sure anything is empty, disconneceted or something before i start, or can i just use the ratchet take off the housing, take out the thermostat, put the new one in, put on the gasket and be done with it. a mechanic said he would charge me 40 bucks to do it, and i'd rather save that money if it isn't hard to do. also, someone told me i will have to buy some glue or putty or something to put on my gasket to keep it sealed? is that true, i thought you could just put the gasket on and be done with it?

Don't know exactly about your thermostat but i'm pretty sure its the same You can just take the housing off and use the gasket. You will need some type of putty/gasket sealer or it will leak. Make sure you don't gouge the mating surface (pretty much impossible). If you do this is where the sealer comes in handy. Refill with coolant and make sure you "burp" /bleed the system of air and thats about it.

Do you have the older 3.8 v6 or the 3800 series I? It's hard to tell from your pic. (The 3800 says "3800 on the intake manifold). 1988 was the transition year and GM fitted both engines simultaneously.

If it's a 3800, there was a problem with getting heat on 1988 cars. I recall back in 1988 there was a recall about the thermostat housing...... coolant would leak past the 'stat' causing a cool - running engine and long warm-ups.

I have found a new stat will often, but not always fix the problem. I worked at a GM dealership back then and changed many stats under warranty.

The housing on the 3800 uses an 0-ring. No sealer is necessary, so long as the housing and manifold opening are not corroded. Just use coolant to lube the O-ring before it goes in.

its a pretty easy fix I replaced mine on my 96 camaro RS in 20 minutes, it has the 3.8liter probably the same as yours. it is recomended that you drain everything but in my opinion is not neccesary as the Thermostat is located so high on the engine. Also on the sealant recomended I say you might as wel use it its cheap and better to be safe than sorry

Do you have the older 3.8 v6 or the 3800 series I? It's hard to tell from your pic. (The 3800 says "3800 on the intake manifold). 1988 was the transition year and GM fitted both engines simultaneously.Actually, the LN3 was replaced by the 3.8 L L27 in 1991-1992 and from 1992 up, this particular engine was referred to as the Series I 3800.

Actually, the LN3 was replaced by the 3.8 L L27 in 1991-1992 and from 1992 up, this particular engine was referred to as the Series I 3800.
Just to clarify my post, the OP should be made aware that his car may have one of 2 quite different 3.8 V6 engines. ,

Back in 1988,for a time, GM listed the older 3.8 SFI 'LG3' engine as the 'standard' motor.
The 3800 LN3 was a 'no-cost' option. Therefore, a 1988 LeSabre might have either engine.
The thermostat and 'no-heat' complaints and recall affected only the LN3 motor. :)

Do you have the older 3.8 v6 or the 3800 series I? It's hard to tell from your pic. (The 3800 says "3800 on the intake manifold). 1988 was the transition year and GM fitted both engines simultaneously.

If it's a 3800, there was a problem with getting heat on 1988 cars. I recall back in 1988 there was a recall about the thermostat housing...... coolant would leak past the 'stat' causing a cool - running engine and long warm-ups.

I have found a new stat will often, but not always fix the problem. I worked at a GM dealership back then and changed many stats under warranty.

The housing on the 3800 uses an 0-ring. No sealer is necessary, so long as the housing and manifold opening are not corroded. Just use coolant to lube the O-ring before it goes in.


im pretty sure my engine says 3800 on it. and when i felt the gasket through the package i thought it felt kind of weird and seemed like an o ring. so since it is an o ring, you say all i have to do is lube the o ring up with coolant and i'll be ok? do i have to take a chizel and smooth down the surface on the housing, or that won't be neccesary?

wow, thanks for all the replies to everyone. its really appreciated.


i also noticed you wrote that these park's would have trouble getting heat and cause a cool running engine. is that why it would take forever in the wintertime for my car to start up. even now in the summer, sometimes my car will start up, run a little rough for a second and either stay on, or cut off, but once i cut it back on its ok. is driving my cool engine in the heat of the summer everyday a good thing or bad thing?

im pretty sure my engine says 3800 on it. and when i felt the gasket through the package i thought it felt kind of weird and seemed like an o ring. so since it is an o ring, you say all i have to do is lube the o ring up with coolant and i'll be ok? do i have to take a chizel and smooth down the surface on the housing, or that won't be neccesary?

The thermostat housing and O-ring fit inside a bore or hole in the intake manifold. The walls of this bore should be clean and smooth. It it is, leave it alone, just lube with coolant. If it has some corrosion or roughness, smooth it out with fine sandpaper (220 or finer) not a chisel. Just stuff a rag in the hole first so sanding debris does not get in the coolant.


i also noticed you wrote that these park's would have trouble getting heat and cause a cool running engine. is that why it would take forever in the wintertime for my car to start up. even now in the summer, sometimes my car will start up, run a little rough for a second and either stay on, or cut off, but once i cut it back on its ok. is driving my cool engine in the heat of the summer everyday a good thing or bad thing?

No, the cooler-running engine does not affect starting issues.
You may have a bad fuel pressure regulator or bad fuel pump. The fuel line should hold approx. 35 psi of fuel pressure, even when the engine is switched off.
If the pressure falls to zero, it will take a few seconds for the pump to repressurize the line and the car will crank lots or run poorly for a few seconds until it does pressurize.
Next time you start it, try turning the key to the RUN position for a few seconds before cranking the engine. Then start the engine. Does it start more easily? If yes, then try pressure-testing the fuel line. There is a test valve on the fuel rail on top of the engine. You will need a special tool to do this, you may be able to rent or borrow one from an auto parts retailer.

Finally, driving a cool-running engine is okay in summer. Cooler than normal engines will get slightly lower fuel economy and will, in theory, wear-out slightly faster than normal until the coolant reaches about 180-190 deg. F. But given the car is already 21 years old, IMO it's not worth worrying about it. :)

My dad had a cool-running '88 Bonneville (same engine as yours) that worked flawlessly for 17 years and 254,000 km. I stopped driving it because of rust, but the engine was still in perfect running shape.
In our winter deep-freeze, I covered about half the radiator with a sheet of cardboard to get a bit more heat. But our winters are a lot colder than Maryland, though, so I do not think you have to resort to that.

man that was really helpful. thanks for the info.