Sierra overheating issue that's driving me nuts!

[Nemesisdawn]

So I'll make this topic as detailed and informative as I possibly can because I'm running out of options here. Video of the issue is included.

 

I did a coolant and radiator flush on my '03 Sierra 5.3 to change the coolant from green ACDelco to orange Prestone. All the old coolant was flushed out of the engine and in with the new. The radiator was bled properly.

 

After driving around for a while, I noticed my temp gauge starting to rise just above midway on the highway, and I can hear the fans kicking on high (did an electric fans swap). I didn't think much of it, but then it refused to cool down even though both the fans and the outside air are blasting through the radiator, and I know that the radiator is clean because there was no corrosion on the inside or outer debris blocking the airflow.

 

I took it back to the shop, reflushed it, bought a new OEM thermostat, nothing helped.

 

As a last resort, I did the following things to make sure everything is  working correctly, and I'll mention some notes:

 

*Thermostat has been replaced

 

*Coolant was changed back to green 50/50 ACDelco, which faired a bit better than the orange Prestone.

 

*Changed the temp sensor and its wiring

 

*Bought a new fan harness from Nelson Performance because the old one got busted from how long the fans were running on high.

 

*Radiator hoses were inspected, nothing is cracked or kinked.

 

*Oil is not milky, nor getting smoke from the exhaust, and I'm not losing coolant, so no head gasket issues.

 

*Car was running fine before the flush.

 

*The car isn't drastically overheating, but there's no reason for the temperature to rise on or above midway when I'm cruising down the highway, and this will make the fans and the harness run harder.

 

*This only happens after I push on the gas or the engine is underload such as cruising on the highway.

 

*Sometimes when the car is idling, it takes awhile for the low fans to turn off, as in, it is cooling down slower than usual.

 

The only two things that are left to suspect are the water pump (not leaking or making noise though), and that there is an air pocket trapped in the engine, and I'd appreciate if someone tells me how to check if there is one.

 

If this behavior is normal, which I'm sure it isn't, please let me know.

 

Here's the video. When the temp begins to rise I'm cruising around 55mph, and only cooled down when I came to a stop and slowly took off again. https://youtu.be/J5jeolKdtc8
 

 

[Brian715]

My 06 sits right there on the 210f line unless I work it hard, then it comes up but cools right back down after I crest the mountain or what ever. It has the electric fans stock. I wouldn't consider just above the 100 line overheating unless it doesn't stop rising. Never heard of overworking a harness before. Either the wiring is able to handle the amp draw, or it isn't. Might be a pocket stuck under the thermostat or something. Had that happen before. I always drill a tiny hole in mine now to allow the bubble to escape.

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[SunShine01]

You seemed to have replaced anything that’s needs to be replaced.

Since you do not have a fan clutch we can eliminate that.

Have you inspected coolant circulation with the radiator?

Is it possible water pump as you day just isn’t pumping ( impellar) issue ? How about your belt and harmonic balancer pulley tension ? Could it be possible your belt tension just is not driving that water pump to crank ? You would have noticed amp issues from the alternator as well ?

The crazy part is, textron pink is where it seemed to originate from ? Weird. Tranny cooler circulating ?

I’d start the engine with the radiator cap off and let it warm up until the thermostat opens to view coolant circulation first. Then look at the belt tensioner next, then finally water pump which should be connected to coolant circulation unless you are clogged.


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[Supreme Pizza]

I would verify that the fans are blowing air in the correct direction. Then I would get an infrared temp gun on eBay or Amazon ($20), to verify the temperature readings. Perhaps the stepper motor in the dash gauge is not working properly. After that I would remove the thermostat to see if that resolves the issue (as a test). The next step would be to remove the oil pressure sender, and check the pressure with a manual gauge. One possibility, is that your coolant flush was not sufficient. Did you flush the heater core during the flush? Perhaps the coolants mixed, and resulted in a radiator clog. 

 

Based on the video, I do not see a problem. Your temps are well within the safe limit. Have you tried to overheat it, just to see if it will? Find a long uphill grade, and tow a trailer up it with your A/C on. Does it actually overheat? 

[Nemesisdawn]

43 minutes ago, SunShine01 said:

You seemed to have replaced anything that’s needs to be replaced.

Since you do not have a fan clutch we can eliminate that.

Have you inspected coolant circulation with the radiator?

Is it possible water pump as you day just isn’t pumping ( impellar) issue ? How about your belt and harmonic balancer pulley tension ? Could it be possible your belt tension just is not driving that water pump to crank ? You would have noticed amp issues from the alternator as well ?

The crazy part is, textron pink is where it seemed to originate from ? Weird. Tranny cooler circulating ?

I’d start the engine with the radiator cap off and let it warm up until the thermostat opens to view coolant circulation first. Then look at the belt tensioner next, then finally water pump which should be connected to coolant circulation unless you are clogged.


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I did run the engine with cap off, heck, I even got it here on video the moment the thermostat opened. The coolant's level increased and it burped air out until the coolant dropped down again. And I did that a couple of times now.

 

In the end I did replace the water pump btw, but to no avail. Although I found out that the old one was already making noise when I got it out, so it wasn't for nothing.

 

I actually found out that the brakes were dragging because I replaced the brake booster and it seemed to clamp down on the calipers. After using spacers between the brake booster and master cylinder the brakes no longer drag and runs cooler, but it STILL runs hot (I'm relying on an OBD2 adapter to read the temp).

 

I've noticed that the faster I go, the hotter the temp gets, and yes, it gets hot enough on the highway that the fans kick on high while driving +50 mph.

 

And when I stop beside the road and shift to neutral, I step on the gas till it gets 2000-2500 rpm for 30 secs or so, and the truck gets  cooler ALMOST INSTANTLY!. Here are screenshots of the coolant temp dropping on my phone while my foot is on the gas on two different occasions. I honestly found about this coincidentally.

 

 

[Nemesisdawn]

18 minutes ago, starman8tdc said:

I would verify that the fans are blowing air in the correct direction. Then I would get an infrared temp gun on eBay or Amazon ($20), to verify the temperature readings. Perhaps the stepper motor in the dash gauge is not working properly. After that I would remove the thermostat to see if that resolves the issue (as a test). The next step would be to remove the oil pressure sender, and check the pressure with a manual gauge. One possibility, is that your coolant flush was not sufficient. Did you flush the heater core during the flush? Perhaps the coolants mixed, and resulted in a radiator clog. 

 

Based on the video, I do not see a problem. Your temps are well within the safe limit. Have you tried to overheat it, just to see if it will? Find a long uphill grade, and tow a trailer up it with your A/C on. Does it actually overheat? 

The fans are blowing in the right direction (towards the engine). I didn't think of the temp gun before, but I'll keep it in mind if all else failed.

 

How will checking the oil pressure switch help? I'm not really knowledgeable in this area.

 

The heater core was bypassed, and the radiator and the coolant were taken out and cleaned again, but to no avail.

 

The temps are within the safe limits indeed, but the problem is that they make my fans run all the times, and run on high even on the highway, and the faster I go the hotter the temps get.

 

In the previous post I attached a video and said what's happening with the truck now. I'm actually beginning to think that the head gasket is "starting" to go out, that's why I ordered a combustion gases tester that's arriving tomorrow.

[Supreme Pizza]

If your engine has oil flow/pressure issues, it will cause the engine to run hotter. The oil has several jobs to do. One is to lubricate, one is to remove debris, another job is to transfer heat away from "hot" areas of the engine. The faster you go, the more heat is generated, and your oil temp will rise. If you were to drive an engine with no oil, the primary cause of failure would be heat related. 

 

Rather than using a heat gun, you could put a "dollar store" thermometer in the radiator. 

 

Now, to resolve the fan issue - just swap out the fan temp switch for a higher rated on. Try going up 10 degrees. 

[diyer2]

Maybe the radiator has a partial block from the flushing.

It still moves coolant as evidenced by your video.

Get it up to running temp and run your hand around the radiator core and feel for hot spots/ cool spots.

Are the top and bottom hoses the same temp?

The radiator hasn't been replaced?

 

[Supreme Pizza]

 

 

30 minutes ago, Nemesisdawn said:

The heater core was bypassed, and the radiator and the coolant were taken out and cleaned again, but to no avail.

 

 

Bypassing the heater core will not help cool the engine. When your car starts to over heat, turning the heater on HI will help cool the engine down. If your car is overheating, and the heater doesn't blow hot air, then you have air in the system, a blockage, or poor water circulation in the cooling system. 

 

 

 

[Supreme Pizza]

25 minutes ago, starman8tdc said:

If your engine has oil flow/pressure issues, it will cause the engine to run hotter.

 

   I have seen engines with mysterious, unexplained overheating issues before. On more than one engine with this issue, The crank bearing ultimately failed. I tend to doubt that the issues were unrelated. When is the last time the oil and oil filter were changed? Is the oil level full on the dip stick? 

 

Clogged oil pump pickup screen?

Oil pickup tube O-ring problem?

Oil filter in bypass mode? 

Poor oil pump performance? 

Poor oil integrity?

 

You could even try an engine oil flush, but if the pickup screen is already partially clogged, then the flush might help or could even make the problem worse. 

 

No guarantees that you have any oil related issues, but I think its a possibility. 

 

 

 

 

[SunShine01]

So you didn’t notice your vehicle being restricted by your brakes ?

Wonder if you’re not getting all your gears ? Are your RPM’s a bit higher than normal while going 60 or so ?


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[Supreme Pizza]

On 12/1/2018 at 1:11 PM, SunShine01 said:

So you didn’t notice your vehicle being restricted by your brakes ?

Wonder if you’re not getting all your gears ? Are your RPM’s a bit higher than normal while going 60 or so ?


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   I don't think his brakes were applied while driving. If they were, he would have a wicked shimmy from the warped rotors, and would probably notice the flames licking up over the front fender when he came to a stop sign. 

 

 

ok, the 2nd pic is probably a fuel leak....

 

 

 

 

 

 

[Nemesisdawn]

On 12/1/2018 at 6:20 PM, starman8tdc said:

If your engine has oil flow/pressure issues, it will cause the engine to run hotter. The oil has several jobs to do. One is to lubricate, one is to remove debris, another job is to transfer heat away from "hot" areas of the engine. The faster you go, the more heat is generated, and your oil temp will rise. If you were to drive an engine with no oil, the primary cause of failure would be heat related. 

 

Rather than using a heat gun, you could put a "dollar store" thermometer in the radiator. 

 

Now, to resolve the fan issue - just swap out the fan temp switch for a higher rated on. Try going up 10 degrees. 

Wouldn't the oil pressure drop if I had an oil pump related problem? I'm sure that my oil pump is working just fine because the gauge (I know, not very reliable) moves in it's proper range. And I did change the oil and filter two days ago, which looked fine to me.

 

Fan temp is controlled through the ECM. It's the Nelson Performance fan harness.

[Nemesisdawn]

On 12/1/2018 at 6:53 PM, starman8tdc said:

 

   I have seen engines with mysterious, unexplained overheating issues before. On more than one engine with this issue, The crank bearing ultimately failed. I tend to doubt that the issues were unrelated. When is the last time the oil and oil filter were changed? Is the oil level full on the dip stick? 

 

Clogged oil pump pickup screen?

Oil pickup tube O-ring problem?

Oil filter in bypass mode? 

Poor oil pump performance? 

Poor oil integrity?

 

You could even try an engine oil flush, but if the pickup screen is already partially clogged, then the flush might help or could even make the problem worse. 

 

No guarantees that you have any oil related issues, but I think its a possibility. 

 

 

 

 

Oil and filter were changed two days ago. 6qt of 5W30 fully synthetic. Heck, even the old oil seemed to still have some life. I never neglect oil and filter changes.

 

Oil pressure seems fine to me. Increases with acceleration, decreases with idling.

 

Head gasket leaks were checked with a combustion gases tester. It turned out negative.

 

I wouldn't really want to try a motor flush, but I'm thinking about Seafoam. It helped BIG TIME in my '04 LS1 GTO.

[Nemesisdawn]

On 11/24/2018 at 8:55 AM, Brian715 said:

My 06 sits right there on the 210f line unless I work it hard, then it comes up but cools right back down after I crest the mountain or what ever. It has the electric fans stock. I wouldn't consider just above the 100 line overheating unless it doesn't stop rising. Never heard of overworking a harness before. Either the wiring is able to handle the amp draw, or it isn't. Might be a pocket stuck under the thermostat or something. Had that happen before. I always drill a tiny hole in mine now to allow the bubble to escape.

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The problem is, it runs perfectly fine inside the city and while idling. The only problem I have right now is the fans coming on high while driving +50mph. And they don't turn off AT ALL. And reading the temp with an OBD adapter, it seems that the faster I'm going the hotter it gets. I don't think the truck should run hot enough on the highway to turn the fans on high.

 

Everything else is fine until I get on the highway or just high speeds in general, in which the fans never want to turn off.