Texas Heat and V8

[ZandT4R]

So lately the heat has been higher than usual here, many afternoons getting to or above 100. I have noticed when the 4R thermometer is reading around 95 and above the engine is much nosier then usual. The best way to describe it is a sound similar to when you first start the engine and it is cold. It is noisy until it warms out. Same sound I am experiencing, only at 70 on the highway after the engine is already warm. Is this a problem? Is this normal behavior for this engine? Anyone else notice this in high temps? One thing I noticed the other day while driving home it was 106 on the thermometer and the engine was noisy. I drove into some rain and the temp dropped to 76 and the engine noise went way. That is how I linked it to the heat.

Thanks for the comments

 

[CJ3Flyr]

It's the fan-clutch working as designed. The fan-clutch is the self contained, hydraulically actuated, finned, center-hub portion of the fan. (If you open the hood with the engine off and you can turn the fan without turning the pulley or belt.) There's a tiny, thermostatically controlled valve (part of the fan-clutch) that opens and closes based on heat in the air right behind the radiator. When the air gets hot the fan becomes closer to a direct drive with the pulley. When the air is cooler the fan-clutch releases allowing the fan to freewheel thus releasing extra horsepower and saving gas via less drag on the belt. It also helps keep noise to the least amount required to get the job done.
:cheers:

 

[ZandT4R]

Awesome! You Da Man. I appreciate the info. I figured it was no big deal, but thought I'd check with the community.

Thanks!

 

[SubSonic]

Great explaination CJ3. That's the best write-up I've seen on fan-clutch cause/effect in some time.

Also note, that when you STOP hearing the fan working harder occasionally in the summer heat...go get your thermostat checked out. I've had several t-stats "stick open" in the past, and it results in an under-temp condition (even pops a CEL in GMs like the Trailblazer - Coolant Temp Under Temp). My first clue that it was about to happen was during several 100º+ days here last year, and was in traffic, idling, running max-AC etc, and the fan never revved up to cool down the radiator, in fact, the engine was running below its "otherwise normal, nearly 210º operating temp"...a few days later, I got the CEL, pulled the code and decoded it to mean a bad t-stat...Sure enough, that was the issue. Installed the new piece, cleared the CEL code and haven't had another issue since.

 

[lawwailok]

also in that situation while driving on freeway, i do notice the rpm is usually a bit higher and the car is not running in overdrive gear by itself.
until it is cool enough, it kicks back into overdrive and fan stops and noise went away.

 

[chayos00]

Just to let you know, I've never experienced something like this and I live in Tucson, AZ where it's been bloody hot here for most of the year! We have been seeing 90-100's since like around March or so.

 

[JAC]

Hey guys..since I am going to Texas this weekend...do you guys recomend to have a coolant flush done?