EDIT: Questions

First I hope this is the right sub-forum to put this thread in. If not I apologize.

I'm thinking my thermostat might be stuck open on my 02 SS. On a cool morning my car doesn't come close to reaching its operating temperature. It doesn't get much higher on the temperature gauge then the line between the bottom of the gauge and the line in the middle of the gauge were the operating temperature for the motor is. Even if I let it idle in the morning for 15/20 minutes to defrost the glass it barely register on the temperature gauge and to get it to start to climb to the first line I have to ride around with a bit of a load on the motor keeping it about 2000 RPM's for a few minutes. When the temperature is warm it will reach close to its normal operating temperature after 5/6 minutes. I'm use to this car reaching full operating temperature after only 3/4 minutes at most even if it's freezing outside 4/5 minutes tops before it's fully up to temp unless maybe its just idling from a cold start.

I know the factory gauge isn't the most accurate thing but it always did a decent job of giving me a good idea of how warm my motor is. In y'alls opinion does this sound like a stuck open thermostat? LS1 thermostats seem to be pretty pricey and I don't want to go spending $40-$50 on something if it isn't the problem.

Can you use a LS2 thermostat and housing with a LS1 water pump? I've read that the LS1 stat won't quite fit the LS2 pump unless you trim it some. I really am not a fan of the LS1 thermostats design along with how it's mounted. Still the one piece design is expensive. If the thermostat breaks again I'd rather just replace the stat and not one with a built in housing. Also why do many websites show pictures of regular thermostats that are listed between $10-$15 and say they fit a LS1? RockAuto being a good example. I'm assuming they're wrong as an OEM stat and housing is a one piece design, correct?

Also I keep reading where people with 02 LS1's are finding out that they have LS2 pumps on their cars. I can see some later LS1's in a C5 and GTO using a LS2 pump but did any of the later Fbodies get the LS2 pump from the factory or is this just something that was added later? Is the LS2 pump better than the LS1 pump where someone does this as an upgrade or is this just done to replace a worn out pump? It seems kind of odd to me that most cars I'm seeing in the forums where people claim to have bought a LS1 thermostat only to find out that theirs cars have a LS2 pump on them are 02's.

I'm pretty sure this is a LS1 thermostat and not an LS2 thermostat on my car. Can someone verify whether I'm right or wrong about what thermostat I have?

 

So did the actual warm-up time change recently? What do you consider a cool morning? IF you let it idle a long time does it ever warm up and get to normal temps? or put out descent vent heat?

My ls1 TA (newer pump, stat, coolant) will still warm up at idle when the temp is in the 30-40*F.. not in any specific time, just in general.

If you really want to investigate you can probably check the coolant temp with a scanning tool to verify. But if you don't have one that might cost more than just replacing the thermostat (~$20 for aftermaket).

I've had both the ls1 and ls2 pumps and and its confusing. I can't speak to everything your asking, however here's what I recall (its been a while):

The picture of the pump you have shows old LS1 style thermostat with the round little ear sticking upright with the plastic connector sticking through it. The LS2's aren't like this. Also, most LS1 pumps have the Rounded/bell-shaped pulley (pulley top), whereas the LS2 pumps have more of a flat top pulley.

I don't know if all manufacturers call it the LS1 and LS2 pumps like on the forums. They seem to call them the late model or newer design for what we call the LS2 style pumps. Even if you have a LS2 that came with an "LS2" pump, if you look at replacements the pumps are generally going to be a mix or same as what's listed for the LS1 cars.

The LS1 and LS2 pump thermostats are slightly different. The original LS1 has the water neck with the Thermostat build into it. I don't believe they could be separated. There's an O-ring style gasket to seal the thermostat to the water pump around the perimeter of the water neck itself.

The LS2 thermostat and housing are two separate pieces which is probably why you see just thermostats available also without the neck. On rockauto almost all the separate thermostats listed as for the "late model pump" or "newer design"..The gasket fits around the thermostat itself and is sandwiched in between the pump and water neck.

There are slight size differences between the two also. I believe the LS2 pump thermostat opening is smaller than the LS1 style pump opening. Again its been a while so I might have this detail reversed. Either way the size is different, ever so slightly. I recall trying to interchange the two and the gasket sealing surfaces didn't seem to mate up correctly due to the different size and gasket design. I did not actually try to run it like this so don't know how it would turn out. I'd be curious to see if any of the aftermarket manufacturers made a separate thermostat/water neck for the older style pumps instead of the one piece thing.

Anyway... I hope this helps. IMO, If your stat is bad, the simplest thing you can do is just replace it with the correct kind and not worry about the design.

 

I have the same issue with my 98 T/A 68k. One day she just stopped warming up normally, temp barely hits 180 unless she idles for 15min+ and then she will drop quickly when the rpms rise. Many 90+ summer days with no change. I replaced my thermostat twice with no change. Tested the first two and they are fine. Replaced the temp sender, flushed the system, flushed the heater core with air, no change. Checked the stat housing with a IR thermometer and it confirms the low temp.

The only real issue I have had since it started, 7 or 800 miles and a year ago, is the heater. She will not blow as hot due to the low coolant temp. Blowing out the core did improve the heat some, but it is not what it was. The core was not clogged at all, but my damn toes were numb and I had to try something.

You Are Not Alone JROC.

 

Thanks guys.

Yeah it just kind of suddenly started not warming up on a cool morning. (25-40 is a cool morning around here this time a year) This morning what I did was I started the car about 15 minutes before I left but I turned the defrost off so no heat was running. This allow the car to reach it's normal operating temperature. When I got in the car and started driving I of course turned the heat on and this caused my temperature to gradually fall off. Not a lot but maybe fell 10-15% of normal operating temperature on the gauge. Yesterday when I let my car idle for 15 minutes before going to work the temperature gauge was barely registering any heat in the motor so I started driving and I cut the heat off and the temperature gauge started climbing to almost operational temperatures in about 2-3 minutes and I then cut the heat back on and the gauge quickly (20-30 seconds dropped down about halfway between not registering heat to operating temperatures.

I ordered a MotoRad thermostat. Much cheaper than I initially thought. Those HyperTech and SLP thermostats are pricey. I sure hope this ends up being my thermostat instead of something like a bad heater core. IDK, but I would imagine that changing a heater core on a Fbody is probably a real bitch unless you can just go through the glove box? In one sense the temperature cooling off noticeably when I turn the heat on leads me to think that it's not the thermostat. With the heat off it comes up to temperature just fine and once the car's up to temperature shouldn't it maintain its temperature pretty closely regardless of whether the heat is running or not? I do know that if you are having over-heating problems that cutting your heater on full blast can help cool it some but I wouldn't think it should be enough to make the temperature gauge drop considerably when running at normal temperature. At the same time I don't smell coolant and the heater does blow hot air when the temperature gauge is reading some heat in the motor. It will still defrost the windshield.

Also I flushed the coolant within the last year and it's still full and new looking. Running 50/50 Prestone Dex-Cool extended life anti-freeze. Someone told me that low coolant can cause the temperature gauge to read low even if the motors running hot. I can understand lower coolant levels not getting the coolant as hot but I thought the temperature gauge read the temperature of the motor and not the coolant or is this wrong?

 

The heater core is still cooling down coolant when your running the heat. If you're already having temp issues, i.e. thermostat stuck open cause low temps.. the heater core (with heat running) is going to even more so help cool down what little heat is in the system.

The thermostat adjusts flow based on temp to try to reach operating pressure. If you're borderline at operating temp (thermostat open) and the heater core starts taking heat from the system without the thermostat closing back up (or engine producing more heat), the temp may drop.

Also check this out.
http://www.pirate4x4.com/tech/billav...CoolingSystems

The engine temperature gauge is based off a coolant temperature via a temp sensor or two.