Temp rises at highway speeds

[Lobo1]

i like to use a couple gm tabs in my truck when i flush the fluid

also you could try running a little water wetter

but you should probably do a head gasket test 1st
before spending any money on additives

Checked compression yesterday. All six were at 205 PSI. Checked all cylinders 3 times.

 

[Lobo1]

Do a gas test for the head gasket, I had a similar problem a few years back. I would have sworn that there was no way the head gasket was the problem....gas leak test proved me wrong. You can buy the kit at NAPA

Haven't really thought about that. Good idea.

 

[Cruisers460]

I checked compression, plugs, fluids you name it. A month later I tried the gas leak test....blown head gasket. Bluedevil
and follow the direction
.http://shop.advanceautoparts.com/p/bluedevil-head-gasket-sealant-38386/7120032-P

 

[Lobo1]

I'd pull and boil the thermostat on the stove to see at what temp it opens up at.

I mentioned this to him when he said he was putting a new therbut honestly don't know if he did.

 

[Lobo1]

Electronic Fan clutches are bad about going out on those. Check for play and/or excessive noise for the first couple minutes on cold start.

New own AC Delco fan clutch two weeks ago. He also took it to the stealership after he put the new fan clutch on and had the latest software for it uploaded. I forgot to put that in the original post.

 

[MRM]

I only looked for a few minutes on a trailblazer forum.
The info it said was that the temp sensor sends a signal to the computer and the computer sends a signal to the dash. It also said that it was often wrong and to check the temp by another means. I dunno?

I only worked on cars where the overflow went to the ground and when they puked sometimes the cap wouldn't hold the specified pressure.

 

[Lobo1]

I only looked for a few minutes on a trailblazer forum.
The info it said was that the temp sensor sends a signal to the computer and the computer sends a signal to the dash. It also said that it was often wrong and to check the temp by another means. I dunno?

I only worked on cars where the overflow went to the ground and when they puked sometimes the cap wouldn't hold the specified pressure.

That could very well be the case here. He said it doesn't actually run hot now, it just shows on the gauge that it is climbing. He said the coolant temp sensor is right next to the oil pressure sending unit which is in a very tight location. LOL gotta love auto mfg engineering.

Added: I told him his scan tool is also reading the data that the temp sensor is giving out that his gauge is showing. At least he knows his gauge itself is working.

 

[brad sweet]

as stupid as this sounds is the radiator air dam still attached under the SUV..it helps direct air into the radiator and is the first thing a woman knocks off at Walmart..it will do the same thing..if air wasn't bled off correctly and or fan clutch

 

[Lobo1]

as stupid as this sounds is the radiator air dam still attached under the SUV..it helps direct air into the radiator and is the first thing a woman knocks off at Walmart..it will do the same thing..if air wasn't bled off correctly and or fan clutch

The air dam is there. He said the radiator shop flushed, filled the system when they took the radiator out to clean it. He assumes they bled the air out when they did this.

The fan clutch is new. He put a Dorman clutch on it about a year ago and it began clicking after about 7 months so he took it back (lifetime warranty) and paid the difference and got a AC Delco fan clutch and put it on. He also took it to the dealership and had them upload the latest software for the clutch (Electronically controlled)

 

[MRM]

You can't say he didn't try. In for final solution.