Coolant Temp Low & Poor Gas Mileage (4BW)

[sethsquire]

Hi all, throughout my ownership, the coolant temperature tops out around 190-192 for a fully warmed up car and stays there unless I beat on it. Lately, I've noticed that it's been getting up to 180-181 and doesn't warm up further from there. I also just took a 100 mile drive and observed (relatively) subpar fuel economy considering there was little traffic; 20-21 mpg vs what is typically 24-25 mpg on the same trip. I also tried romping on it a few times to the extent I was able to on the highway and it still never got over 181 degrees.

I brought the temperature issue up over the winter when I brought the car in to the dealership to have a few issues looked at. The dealership told me they "tested" it and concluded there wasn't a problem and maybe it just wasn't heating all the way up because it was cold out. At the time, I hadn't observed the poor fuel economy because most of my trips are short and I'm already getting bad fuel economy.

It sure sounds like either a bad coolant temp sensor or thermostat to me, causing it to run rich and fuel economy to suffer, but has anyone had a similar experience?

 

[jbawden]

That does seem low by modern standards, but I don't have a 4. The fact that it stays at a consistent, lower temp is interesting. Is the temp controlled purely by a plan 'ol thermostat or are there other mechanisms, I wonder.

 

[sethsquire]

ETA: I just realized I could display my oil temp as well as coolant temp. Turned on the display and romped on the car for a couple minutes, I can't imagine this disparity is normal.

 

[sethsquire]

That does seem low by modern standards, but I don't have a 4. The fact that it stays at a consistent, lower temp is interesting. Is the temp controlled purely by a plan 'ol thermostat or are there other mechanisms, I wonder.

I don't know, but I'm not aware of anything beyond what's in a normal car.

 

[AC2024]

ETA: I just realized I could display my oil temp as well as coolant temp. Turned on the display and romped on the car for a couple minutes, I can't imagine this disparity is normal.

What disparity? Oil temp will always be higher than coolant temp on a fully warmed car. At first glance i dont find any of your figures to be too far out of the envelope of reasonably normal.

Your oil temp certainly seems on the lower side after “romping it” but you said you did it on the highway where there is a ton of cooling happening. Also in 22000 miles i have never seen 24mpg in a single 50 mile interval so we may have different measuring sticks. Fwiw i never look at coolant temp and my routine commuting highway oil temp is ~200 on a mild day, ~220 in stop and go or if im giving it the beans on backroads, ~250 heatsoaked at my track pace.

Ill try to remember to flip on my coolant temp gage and report back after my highway drive home tonight.

 

[NewCaddy]

Temps look normal. As far as MPGs, possibly bad batch of gas, not sure if you’ve switched brands as well.

 

[sethsquire]

What disparity? Oil temp will always be higher than coolant temp on a fully warmed car. At first glance i dont find any of your figures to be too far out of the envelope of reasonably normal.

Your oil temp certainly seems on the lower side after “romping it” but you said you did it on the highway where there is a ton of cooling happening. Also in 22000 miles i have never seen 24mpg in a single 50 mile interval so we may have different measuring sticks. Fwiw i never look at coolant temp and my routine commuting highway oil temp is ~200 on a mild day, ~220 in stop and go or if im giving it the beans on backroads, ~250 heatsoaked at my track pace.

Ill try to remember to flip on my coolant temp gage and report back after my highway drive home tonight.

Thanks, and you're right that oil temp should settle a little higher than coolant temp so I was wrong there. I'm only noticing the differences because the coolant temp always settled about 10 degrees higher up until a few months ago, and I've taken that same drive a bunch of times and always gotten in the low to mid 20's (I'm talking humming along at 65-70) and this was noticeably lower.

 

[CT4-Venom]

FWIW, I was doing some spirited canyon driving this weekend and my coolant temp never went over 186. It was not too warm out about 80 with a nice cool breeze blowing. My fun got cut short due to a getting a nail in the right rear tire. Activate GM tire inflator! It worked great and I was able to limp to a tire shop for a tire repair at 4 pm on a Sunday!

 

[sethsquire]

FWIW, I was doing some spirited canyon driving this weekend and my coolant temp never went over 186. It was not too warm out about 80 with a nice cool breeze blowing. My fun got cut short due to a getting a nail in the right rear tire. Activate GM tire inflator! It worked great and I was able to limp to a tire shop for a tire repair at 4 pm on a Sunday!

I envy you guys in Cali with your canyons. I've visited a couple of times and the driving roads there are incredible. There is absolutely nothing resembling that where I live.

 

[CT4-Venom]

I envy you guys in Cali with your canyons. I've visited a couple of times and the driving roads there are incredible. There is absolutely nothing resembling that where I live.

It is nice, and I am lucky that I can drive 15 minutes in any direction and find a good one. Where were you when you were out here?

 

[sethsquire]

It is nice, and I am lucky that I can drive 15 minutes in any direction and find a good one. Where were you when you were out here?

Last time we started in the bay area and then drove all the way down the PCH to get to the LA area where my wife has family, and then all around the area when we were there.

 

[CT4-Venom]

That’s cool. That is a great drive! A bit on the long side but the scenery makes up for it.