2002 Trailblazer Thermostat Question

[Mark_Walk]

I've got my old Trailblazer that I bought new in 02. First year they made the TB. I recall back when new the temp gauge was always in the middle at 210 deg. At some point a few years ago had some work done and the thermostat replaced and ever since then the temp stays a few marks to the left of 210..around 160. I've noticed that I have some varnish now on the dipstick and under the oil fill cap. Could this be caused by running too cool? Also, I'm now wondering if this would affect rich/lean mixture if computer is adjusting / staying in warm up mode, thinking I just started engine? Changing the thermostat is a pain in this vehicle but I'm thinking it may be worth it to get it up to full temp.

 

[supton]

Got a code reader like a Scanguage? It could tell you operating temp.

But it sounds like time for a thermostat.

 

[The_Eric]

Change the stat with an OE Delco. For as often as it's going to need done, it's not that bad of a job. Need a long extension and swivel (I think).

 

[Mark_Walk]

Yea, they probably put a Chinese made aftermarket t-stat in it. Do some shops put in lower temp t-stats on purpose thinking running cooler is better for the engine?

 

[SnPb]

Another thing to consider is replacing the temperature sensor, located in the engine block just above the thermostat. I replaced the thermostat in my 03 twice and the temperature reading was still low, sometimes erratic, until I replaced the sensor.
The factory thermostat is rated at 190 deg F and is the one that should be used.

 

[Mark_Walk]

wonder if I can get to the sensor without taking the alternator off?

 

[SnPb]

I've heard of people able to replace the thermostat without taking anything else off first, but not me. I took the battery and battery box out, along with the alternator. The air conditioning plumbing runs near the alternator in a location that makes it difficult to get a wrench onto one of the alternator bolts. It's a good time to swear at the Engineer that thought this was a good location for the thermostat.

 

[Mark_Walk]

I've also got a leaky high pressure PS line as well. May be a good time to do it all in one shot.

 

[Falken]

Probably the thermostat is junk and Stuck Open.

 

[Mark_Walk]

No, I don't think it's stuck open. It warms up pretty fast..just not past about 160 deg.

 

[The_Eric]

The few I've done, I went in through the wheel well. Good point about the sender. Might as well replace that too as I think they were problematic.

 

[147_Grain]

Existing thermostat is likely opening too soon and is the incorrect unit.

Install an OEM unit and re-evaluate.

 

[Falken]

Maybe the ECT sensor is bad. Hook it up to a scanner and see if there are any codes.

 

[PF52]

If it'll help, there are several videos of this procedure on Youtube. Its not bad at all.

I pointed a friend toward those videos when he needed to change his thermostat. Once he was done, he claimed it was easy! And it was sure worth the several-hundred dollars or whatever it was he had been quoted.

Give it a try.