Started By
Message

Noticed my engine temp is starting to waiver

Posted on 5/31/23 at 9:50 pm
Posted by GREENHEAD22
Member since Nov 2009
20045 posts
Posted on 5/31/23 at 9:50 pm
So I noticed my engine temp is starting to waiver a bit, it will go up some and then come back down or stay slightly elevated.

I have never noticed this before and I am very vigilant of my engine parameters due to all the issues I have had.

I recently had to get a stuck lifter fixed so I did a complete AFM delete. They changed out all the coolant when they did this but I am wondering if some debris may have got into the system. That or my thermostat is sticking.

What say the OB mechanics?

2016 GMC 1500
Posted by highcotton2
Alabama
Member since Feb 2010
10056 posts
Posted on 5/31/23 at 9:58 pm to
Could be a sticking thermostat. Could be a bad engine fan clutch.
Edit: Just noticed you said 1500 that would be an electric fan.
This post was edited on 5/31/23 at 10:02 pm
Posted by Purple Spoon
Hoth
Member since Feb 2005
19298 posts
Posted on 5/31/23 at 10:01 pm to
Check thermostat and water pump.

Posted by GREENHEAD22
Member since Nov 2009
20045 posts
Posted on 5/31/23 at 10:07 pm to
What is the prognosis on the fan? Only a matter of time before it completely fails?
Posted by White Bear
Yonnygo
Member since Jul 2014
16305 posts
Posted on 5/31/23 at 10:13 pm to
Is there a way to install an analog gauge to compare?

I would say down the road (no hills, etc) it should be fairly constant. I’d be thinking thermostat if not electrical.

I had a 08 with e-fans I used to compare trans temp with the engine temp. Engine temp would run about a needle width past 210. The fan speed was quirky on it too though imo.
This post was edited on 5/31/23 at 10:30 pm
Posted by highcotton2
Alabama
Member since Feb 2010
10056 posts
Posted on 5/31/23 at 10:24 pm to
quote:

What is the prognosis on the fan? Only a matter of time before it completely fails?


I was just thinking about a 2500 that has an engine driven fan with a clutch. Had a clutch go bad recently and it would get hot while sitting stationary and the ac would quit cooling. New fan clutch fixed it.
On yours I guess it is a double electric fan? I can’t remember. Might just check and make sure both fans are turning.
Posted by GREENHEAD22
Member since Nov 2009
20045 posts
Posted on 5/31/23 at 10:28 pm to
Yea it is a double fan.
Posted by MasterDigger
Member since Nov 2019
2356 posts
Posted on 5/31/23 at 10:51 pm to

I've seen where a small leak can cause an air pocket to sit near the temp sensor and drop the temp on the gauge super low until the coolant catches up and flows over the sensor again, briefly showing a true high temp. This cycle happened constantly.
quote:

They changed out all the coolant when they did this
Maybe an air pocket/low coolant or bad/sticky thermostat. Or they put it in backward
Posted by DownshiftAndFloorIt
Here
Member since Jan 2011
69125 posts
Posted on 6/1/23 at 6:12 am to
Does it have any kind of active air control system? Automatic grille shutters, electric cooling fans, anything like that? Can you influence the behavior by turning the ac on full blast vs turning it off? Is it fully repeatable? Did they do any software updates to the truck? Are you looking at an analog gauge or a digital readout value?

I'll think of some more questions later.
Posted by Animal
Member since Dec 2017
4341 posts
Posted on 6/1/23 at 6:14 am to
I have been dealing with something similar for years. I am not a mechanic and I have the bills to prove it.

My truck is a 2004 with 420k miles on it.

I have replaced the thermostat, water pump, and radiator. The heater coil was removed and bypassed years ago.

Check your hoses for leaks around the hose clamps. That is what it was for me the last time. And I felt like a complete dumbass for taking it to a mechanic for him find it and tighten it up in about one minute.
Posted by Animal
Member since Dec 2017
4341 posts
Posted on 6/1/23 at 6:16 am to
I have been dealing with something similar for years. I am not a mechanic and I have the bills to prove it.

My truck is a 2004 with 420k miles on it.

I have replaced the thermostat, water pump, and radiator. The heater coil was removed and bypassed years ago.

Check your hoses for leaks around the hose clamps. That is what it was for me the last time.

ETA: In the mean time, keep 2 gallons of water in the back of your truck until it is resolved. I did not do that at first so I probably have about 2 pairs of shoes to add to the casualty list.
Posted by tigerinthebueche
Member since Oct 2010
36958 posts
Posted on 6/1/23 at 6:33 am to
My 2017 does the same. Especially if I’m towing something. Always goes back to normal though so I said frick it. GM has lost a devout brand loyalist with this latest vehicle.
Posted by PillageUrVillage
Mordor
Member since Mar 2011
15339 posts
Posted on 6/1/23 at 8:25 am to
My wife’s previous POS car (Buick Enclave) did the same thing and it was the water pump.
Posted by Sparetime
Lookin down at LA
Member since Sep 2014
972 posts
Posted on 6/1/23 at 8:34 am to
1. See if ECT sensor reading matches gauge. Stepper in cluster could be going out, common. Or ECT is starting to short.
2. Turn AC on and monitor while in park. If it does more rapidly in Park, then fans are weak.
3. If none of the above, check radiator pressure. If in spec, flush system well.

Thermostat would be last thing i would accuse on that truck.
Posted by concrete_tiger
Member since May 2020
7178 posts
Posted on 6/1/23 at 9:08 am to
I have a tiny leak in my coolant valley and I can either get it fixed or top off every now and then. Dumb question, but have you checked your coolant levels when it fluctuates?

I thought it was a sensor at first, or thermostat... but it was just low. Doh!
Posted by GREENHEAD22
Member since Nov 2009
20045 posts
Posted on 6/1/23 at 5:11 pm to
Good coolant level, both fans are running. It is intermittent and acts in a way that makes me think the thermostat is sticking, freeing, sticking, freeing etc.

I also noticed the transmission fluid is running higher than before, I have the new stat in which is set for 145 I believe and it is getting close to 200.
Posted by Swazla
Member since Jul 2016
1648 posts
Posted on 6/1/23 at 6:56 pm to
quote:

Maybe an air pocket/low coolant or bad/sticky thermostat. Or they put it in backward


Coolant temp sensors work on water, not so well on air. So maybe get the guys that did the work to purge the system.
Posted by DownshiftAndFloorIt
Here
Member since Jan 2011
69125 posts
Posted on 6/1/23 at 7:10 pm to
In my experience, it's almost never the thermostat. It's cheap and easy to replace though so wtf, try it.

It's usually a coolant leak or an airflow issue.
Posted by GREENHEAD22
Member since Nov 2009
20045 posts
Posted on 6/1/23 at 7:26 pm to
The reservoir is full and I didn't see any leaks. AC is still blowing cold.

Air flow, you thinking a weak fan?

I am wondering if the screwed a setting up when they tuned the motor on the AFM delete.

Update, I did possibly find a very small leak on the line going to the transmission.




I was really hoping to get another 50-75k out of this POS with all the work I have had done to it but I am thinking hard about selling this bastard.
This post was edited on 6/1/23 at 8:25 pm
Posted by DownshiftAndFloorIt
Here
Member since Jan 2011
69125 posts
Posted on 6/1/23 at 8:39 pm to
quote:

you thinking a weak fan?


Maybe. If they are electric you can check the amperage each one is drawing. Usually something like active grille shutters not acting right, too many bent fins on the radiator, piece of the shroud missing, something along those lines.

It's difficult to diagnose if it isn't something super obvious without specialized tools. If you aren't losing coolant than it isn't a leak. Does it happen at idle or only while driving? If it'll do it idling, it can be much easier to troubleshoot.
first pageprev pagePage 1 of 2Next pagelast page

Back to top
logoFollow TigerDroppings for LSU Football News
Follow us on X, Facebook and Instagram to get the latest updates on LSU Football and Recruiting.

FacebookXInstagram