Coolant Pressure 6.0L Vortec

[adventurenali92]

Parts under a hood can go out even at only 90k. I learned that with my water pump going out at just over 86k.yoire driving your truck things are going to wear down. Especially towing. Towing is ******* vehicles. If it's a cooling system issue you shouldn't have needed a trans flush. Two different systems. Check your radiator and water pump for leaks. The water pump in mine leaked water out through the weep hole. Even a small leak in your radiator can seep enough coolant out to let your truck run hot. I'd check both of those.

 

[TheAutumnWind]

I am resurrecting this thread to provide an update.

My problem still isn't fixed. The truck will begin to get warm (higher than normal operating temperature of 210*) while sitting at idle. What I have noticed is that this happens when the outside temperature is more than 100* and the transmission temperature is over 180*. I took the truck to a local dealership yesterday and had them flush the transmission. I am going to call them tomorrow because when their oil lube technician did the oil changed and checked the air filter, they removed the intake tube for some reason and lost one of the damn clamps. I also want to know if their "transmission flush" involves dropping the pan and changing the filter.

Since the transmission flush didn't help, I went ahead and changed the fan clutch today. Two weeks ago, I went ahead and replaced the upper and lower radiator hoses, surge tank and surge tank cap. The system NOW builds and holds pressure, it was not prior. However, it still gets over normal operating temperature when sitting at idle for more than 5 minutes.

So, here is the full list of what I have done.

1. Upper and Lower Radiator Hoses (AC Delco OEM)
   
2. Thermostat (AC Delco OEM)
3. Coolant Surge Tank (AC Delco OEM)
4. Coolant Surge Tank Cap (AC Delco OEM)
5. Fan Clutch (Murray)
6. Flushed Cooling System (twice) and used AC Delco Dexcool

I have access to an AC Delco parts distributor so I try to use OEM parts when I can. The only reason the fan clutch is a Murray is because my distributor isn't open on Sunday's and I wanted to do it today.

I am at a complete loss! I towed my brothers little trailer (single axles, enclosed, less than 2000lb) about 30 miles to my sisters house today and the engine got to around 225* and the transmission got to about 205*, with that little trailer and the outside temperature around 105*. I am planning on attempting to pull my 8000lb toy hauler up north this coming weekend but I am afraid the truck is going to actually overheat and leave my family and I stranded. If anyone has ANY suggestions, I am all ears. I am sick of throwing money at it but don't have the $130/hr for the dealer to diagnose the issue. I am very mechanically inclined (rebuilding my Duramax LLY right now) and I have always worked on my own vehicles.

The only items I have yet to replace in the cooling system are the water pump and the radiator. The truck has less than 90k miles on it! Please, any suggestions are appreciated!

Thank you!

I sat in traffic with 110*+ temps with my nali loaded up and my temps crept past 210* coolant and 190* trans, and this was with an upgraded trans cooler (albeit a cheapy 12x12x.75" one)

I'd recommend that you consider a nice big trans cooler, and electric fans.

 

[millerladam]

Parts under a hood can go out even at only 90k. I learned that with my water pump going out at just over 86k.yoire driving your truck things are going to wear down. Especially towing. Towing is ******* vehicles. If it's a cooling system issue you shouldn't have needed a trans flush. Two different systems. Check your radiator and water pump for leaks. The water pump in mine leaked water out through the weep hole. Even a small leak in your radiator can seep enough coolant out to let your truck run hot. I'd check both of those.

Yes, I understand wear and tear, even at only 90k miles. I also understand towing is ******* vehicles and that I didn't necessarily need a transmission flush when it's a cooling system issue. My thought was that it had something to do with the transmission fluid having been broken down and the cooler not being able to cool it, thus, since the transmission oil is part of the radiator (from what I gather from my build specs), the transmission oil was getting too hot for the radiator to cool it down and therefore was heating the coolant causing both temperatures to just climb. The cooling system is not losing any coolant. That being said, I have checked for any signs of leaks on both the radiator and water pump and so did the dealer and neither of us found anything.

I sat in traffic with 110*+ temps with my nali loaded up and my temps crept past 210* coolant and 190* trans, and this was with an upgraded trans cooler (albeit a cheapy 12x12x.75" one)

I'd recommend that you consider a nice big trans cooler, and electric fans.

When you say "crept", where do you suppose it was? How warm? When it comes to electric fans, I am very cautious about this. I don't want to cause any further cooling issues and if I spend the money and it doesn't help, then I am out all that money.

 

[Jason_S]

You've flushed your coolant twice, replaced a few hoses, the reservoir cap and tank. Any chance you didn't get all of the air out of the system? I'm a fan of drilling a 1/16th hole on the top of the Thermostat, if there isn't already one there. If the Dex-Cool was not maintained by the previous owners, you could have some blockage in your radiator.

If you had head gasket issues, you should have seen evidence of it when you changed your plugs.

When you replaced your fan clutch, did you get the shroud back into place? Was is it all there before you started?

What is the condition of your serpentine belt tensioner? Any chance that the belt is slipping?


Pulling a trailer is not always the best tell. Pulling with a tailwind eases the load some, but lessens the airflow through your radiator and trans cooler. You might not really see a change in engine temp, but you will see a noticeable rise in transmission temperature.

My first thought is that there are still some air pockets in your cooling system.

 

[TheAutumnWind]

Yes, I understand wear and tear, even at only 90k miles. I also understand towing is ******* vehicles and that I didn't necessarily need a transmission flush when it's a cooling system issue. My thought was that it had something to do with the transmission fluid having been broken down and the cooler not being able to cool it, thus, since the transmission oil is part of the radiator (from what I gather from my build specs), the transmission oil was getting too hot for the radiator to cool it down and therefore was heating the coolant causing both temperatures to just climb. The cooling system is not losing any coolant. That being said, I have checked for any signs of leaks on both the radiator and water pump and so did the dealer and neither of us found anything.



When you say "crept", where do you suppose it was? How warm? When it comes to electric fans, I am very cautious about this. I don't want to cause any further cooling issues and if I spend the money and it doesn't help, then I am out all that money.

I understand about the electric fans upgrade, but definitely do the trans cooler. As the transmission heats up it adds heat to the radiator which transfers that to the coolant system obviously. A tru cool 40k can be had for ~$135 and that is the one I would suggest if lots of hot weather towing, and my (open box) hayden 679 I picked up for like $40. This will increase reliability as hot trans fluid kills transmissions.

I got temps to the 215-220* range coolant wise and 195-200* range trans wise.

That being said ~190* trans temps on a stock vehicle in 105* ambients while towing? THat's totally normal. Not something I would be happy about, but normal. Increase your cooling capacity beyond stock if you want to address that.

 

[Jason_S]

I understand about the electric fans upgrade, but definitely do the trans cooler. As the transmission heats up it adds heat to the radiator which transfers that to the coolant system obviously. A tru cool 40k can be had for ~$135, and my hayden 679 I picked up for like $40. This will increase reliability as hot trans fluid kills transmissions.

Depending on the options of his 2500, it already has an "up-graded" transmission cooler from the factory. And if I remember correctly, the base trans cooler is the upgraded one on the 1500's and larger than what was standard for the Denali. On a 95* day, I had about 8K on a trailer behind my 09 2500 and only got above 200* when I had a tail wind for while, engine temp never budged off the 210* mark. My 07 LTZ, handled about a 6.5K load on a similar day with trans temps reaching 220*. FWIW, I hated towing a heavier load with the coil suspension on the LTZ.

Before I went through the hassle of adding a pusher electric fan, I would swap the Tahoe/Yukon electric fan setup, ditch the mechanical fan and get a tune to make it work like it was factory.

 

[#1taho]

I didn't read every post here but I did read a few. I seen you replaced some parts but did you replace the water pump or thermostat? The impeller goes bad sometimes.

 

[millerladam]

Depending on the options of his 2500, it already has an "up-graded" transmission cooler from the factory. And if I remember correctly, the base trans cooler is the upgraded one on the 1500's and larger than what was standard for the Denali. On a 95* day, I had about 8K on a trailer behind my 09 2500 and only got above 200* when I had a tail wind for while, engine temp never budged off the 210* mark. My 07 LTZ, handled about a 6.5K load on a similar day with trans temps reaching 220*. FWIW, I hated towing a heavier load with the coil suspension on the LTZ.

Before I went through the hassle of adding a pusher electric fan, I would swap the Tahoe/Yukon electric fan setup, ditch the mechanical fan and get a tune to make it work like it was factory.

In response, my Yukon has an external transmission cooler in front of the A/C condenser so going from the front most part of the truck in towards the engine, I have: transmissions cooler, A/C condenser, radiator, hydraulic / mechanical / clutch fan, then engine. As previously mentioned, I am afraid of swapping the factory clutch fan with an electric setup in the instant that it doesn't cool effectively and then I am out the cost of the electric fans. I would like to put a larger radiator in it. Do you know of any larger radiators that are drop-in for the 2500? I am half tempted to replace the water pump on Thursday before we leave as well as add an electric fan to the external transmission cooler. I am only hesitant on the electric fan because I have read that it needs to be tapped into a thermostat instead of on a switch or constantly running. Any ideas?

I didn't read every post here but I did read a few. I seen you replaced some parts but did you replace the water pump or thermostat? The impeller goes bad sometimes.

Yes, I have replace the thermostat. The only parts I have not replaced are the water pump and radiator.

 

[TheAutumnWind]

In response, my Yukon has an external transmission cooler in front of the A/C condenser so going from the front most part of the truck in towards the engine, I have: transmissions cooler, A/C condenser, radiator, hydraulic / mechanical / clutch fan, then engine. As previously mentioned, I am afraid of swapping the factory clutch fan with an electric setup in the instant that it doesn't cool effectively and then I am out the cost of the electric fans. I would like to put a larger radiator in it. Do you know of any larger radiators that are drop-in for the 2500? I am half tempted to replace the water pump on Thursday before we leave as well as add an electric fan to the external transmission cooler. I am only hesitant on the electric fan because I have read that it needs to be tapped into a thermostat instead of on a switch or constantly running. Any ideas?

My denali had an external trans cooler from the factory. A 12x12" plate and fin external was a noticable upgrade.

 

[Jason_S]

Personally, I have never had need to try and find a larger radiator. That being said, a very quick search on Rock Auto, found that the same radiator from spektra is used in the '07 Yukon XL 6.2L 1500, 6.0L 2500 and Sierra 6.0L 2500. The 6.6L D-max Sierra 2500 uses a different radiator. Chances are, that the D-max radiator has more cooling capacity, but should probably bolt in.

You could order one for the d-max from Amazon and see if it fits. If it does, then you have your answer, if not returns are pretty painless with Amazon.