Low engine temp on cold days

[Hippie459MN]

I live in central Minnesota and I recently bought a 2004 Chevy Thahoe with the 5.3 and the truck has been great but recently I have noticed an issue. Temps here have been well below zero for the past week straight and I have noticed that my Tahoe has been having very low engine temps at idle. It wont get over about 150 deg and stays in that 140-150 range no matter how log it sits and idles but if I start driving it will very slowly go up to about 195-200 and stay there but if I stop for about 5 minutes or so, the engine temp will drop right back down and if I shut the truck off, within about 10 min or so, it will be down to about 120 or so if I start it back up and takes a good while to get back up to operating temp. I know its been stupid cold out (-13 F with a -27F windchill as I type this) but I have never had this happen before on any other vehicle. Im thinking the thermostat is stuck open just a little bit cause its not cooling way down to where its cold cold but also not over heating. Just wondering if anyone else has had this issue and if so maybe what else to look at. Also, the coolant is full in the tank. I would assume if it was the water pump it would over heat and/or be leaking so I am going to rule that out for now. I have a 1997 suburban that it can be -20 F out and within 15-20 minutes letting it idle it will be up to about 210 and maintain it no matter how cold it is out. Any ideas before I tear into this thing would be awesome. Thanks.

 

[Hippie459MN]

I was just doing some looking around online it looks like a lot of auto parts stores have a 160 deg t-stat and a 187 deg t-stat and im wondering if maybe someone didnt put a 160 deg t-stat in my Tahoe at one point. Looks like I might be swapping it out just to be safe. Now to find a warm place to do it seeing it -15 below here and I dont have a garage.

 

[Doubeleive]

even if it was a lower thermostat the temperature would be consistent all the time except when warming up in the morning or if it sat for a period of time during the day, yours is probably stuck open, it's not uncommon.

 

[Hippie459MN]

Thats kind of what im thinking. At least its not over heating on me so it is derivable. I didnt notice this issue until it got really cold out. We went from 250-30 deg days to -15 the next and thats when I really noticed the issue. It was slow to warm up before but not even close to what it is now that its super cold out.

Thinking back, I have an 1999 GMC pick up with the 5.3 in it also that has been parked at my moms for about 2 years now (still runs great, just rusted out so bad. Farm truck) and never had this issue either.

Now to figure out if its the one piece t-stat and housing or where I can buy just the t-stat. 2 places said they are different I guess.

 

[PG01]

Check fluid level.... prob low

 

[Doubeleive]

Check fluid level.... prob low

how would it run cold with low coolant? explain.....

 

[Hippie459MN]

Check fluid level.... prob low

I stated in my original post that the coolant level is full. Also, if it was low it would over heat, not run cold.

 

[RED TAHOE LS]

Kevin, welcome to the forum from Georgia Dawg country. As OP have stated, you need a thermostat, but as well I think you've got some AIR POCKETS in your cooling system, so change the thermostat with a 195, open the heater control and only fill the radiator about 2" below the top and let it run until the engine is warm @ 195, and another 10 minutes or so to burp out the air.
Good luck to you in the cold, it's coming here next week in the teen's.
David g..............

 

[HiHoeSilver]

how would it run cold with low coolant? explain.....

You're gonna need more popcorn.

 

[HiHoeSilver]

Check fluid level.... prob low

You gonna tell us wth you're talking about?