I have a 1995 Buick Regal 3800 Series 1 as my winter car. Car runs great. During the summer I flushed out the coolant and changed the leaky timing cover gasket. The motor has actually been rebuilt from the block, up by someone else in my family.

The car seemed okay until it started being a high of in the 30s here in Buffalo. The car just didnt seem to completely warm up. Even though the thermostat was newer, i changed it anyway to only find the same problem. I will get heat in a reasonable time frame ( compared to the other 3800s ive had) but the temp gauge seems to stall out between the bottom Cold line and the next 1/4 mark. If the car sits and idles, it will get warm enough, to the 1/4 mark where it should be and the thermostat does open.

As im driving, it'll get to its normal middle spot but stalls out. If i keep the blower motor off, it does slowly creep up higher sometimes, but if i turn the blower on, it'll actually drop down some. Is it too cold out for the car? Would card board in front of the radiator help? I don't think i have air in the system. The temp gauge seems accurate.

Thanks!

I wondering if the t-stat is stuck open slightly, or installed upside down. How'* the weather up in your neck of the woods? Getting cold here in Elmira.

It was doing this with the old stat (which was only 2 years old) so that'* why I put a new stat in. I had it idle all the way up today and it didn't open until the guage got to it'* normal running spot. I did drill a 1/8in air hole in it but I've done that with every thermostat.

As I drove it tonight, I didn't turn on the blower until it creeped all the way up to normal temp, turned on the blower and the temp slowly creeps down as I drive lol. Heat coming out of the vents is still pretty warm for being a negative wind chill.

I don't think it'* been above 15 degrees since Christmas eve. And there'* almost always been a wind so the wind chill has been negative. I think it'* a high of 9 tomorrow.

What temperature thermostat are you using?

To find out for sure what'* going on, you would probably want to check it by scanning live data to get what the computer is seeing.

Also, the gauge on my '94 is not completely linear, which I suspect yours isn't either. I believe 160* is halfway between 100 and the quarter mark. Are you getting a check engine light also?

I am using a 195F stat. Stamped on that bottom of it.

Its a 1995 therefore it only has the OBD 1. Can i even live data from it? Or find the correct plug?

Im sure its not linear but i had another Regal, 1996, Series 2 and it sat at/little above the first 1/4 mark. Which is where the thermostat does open... It just takes alot to get there.

I do not have a check engine light.

With ambient temp at 15F, and vehicle at normal operating temp, what is the air temp coming out of registers with full heat in vent position, using a thermometer in the register?

I am not sure which OBD port your car will have, but it will either be the ALDL port (GM Specific) or OBD 2. It'* one of the years the dreaded OBD 1.5 was in full force. It behaves like OBD 2, but communicates with OBD 1 protocols. You would need a scanner specifically compatible with 94-95 3800 engines.

In thinking about it, 1/8th inch may be a bit too big. You could possibly try going smaller. It'* done just to bleed air through. Also make sure there is a rubber seal on the thermostat when the thermostat goes in.

To be honest, I have been encountering a similar drop in operating temperatures, and I haven't been fighting the frigid cold that you have.

Some thermostats have a checkball system for bleeding air, so there is no need to drill it. If the heat is still working fine, I wouldn't be too worried about it. The car should set a trouble code (and in turn, SES light) if it spends too much time below 170*, which seems to be the magic number.

Also keep in mind, Series 2 is a bit different of an animal.

That'* also not even counting that GM gauges are known for many things, none of which is their accuracy.

You sound like you know what you are doing, so if you feel you need to restrict airflow up front, you would know when to pull the obstruction out. I don't know that there is enough of an issue that warrants action just yet.

Then again, I am in the desert southwest, and making sure there is not pure water in the cooling system for that one freeze night a year is about the extent of my expertise.

I agree with everyone. The 1/8 hole is a tad too big. Stant makes a t-stat with a hole pre-drilled with a floating ball that closes it when the coolant hits the t-stat. Pretty nifty design.

With his 95 being a Series 1 engine, I'm safe to assume he has the PRE hybrid OBD1.5, which means, he probably has the 12 pin connector and not the 16 pin system. A trip to the GM dealer where a Tech1 scanner can read the live data from the computer. It should be standard labor rate for a diagnostic scan to see what the engine temp sensor is seeing for coolant temp.

Yes, GM cluster temp gauges tend to be flaky at best, but I agree with Tech2, what is the REAL feel of the air temp coming out of the vents? You could have a blend door not directing all the hot air correctly.

Another possibility is, whomever refilled the coolant, used the incorrect mix. Get yourself a $5 coolant tester and see what the rating is.