GM 6.2 liter issues

[Motor Boater]

My Denali has the 6.2. I love this engine and it has always been a beast towing my 24 wakeboat until last weekend. All the sudden this thing is heating up. If I turn off the AC it cools down. Does the compressor have that much drag? Or maybe it’s going bad? The truck has 100,000 miles on it so it’s probably due for a coolent flush, plugs etc. any other thoughts or common issues with these motors?

 

[Carrera205]

In on this I have the same vehicle but it has 56,000. No issues. It has been hot as fuk plus towing and AC maybe was just a little much.

 

[bk2drvr]

What do you mean by heat up? What are your coolant and trans temps?

I have an Escalade with the 6.2 it runs hot also. Hotter than I’d like, both coolant and trans in the 230+ degree range when towing on a grade. I wish GM put bigger radiators in these things. Costs almost nothing.

 

[lbhsbz]

230 is not hot, if that’s the real temp.

 

[Motor Boater]

What do you mean by heat up? What are your coolant and trans temps?

I have an Escalade with the 6.2 it runs hot also. Hotter than I’d like, both coolant and trans in the 230+ degree range when towing on a grade. I wish GM put bigger radiators in these things. Costs almost nothing.

235 degree if I was careful in the hills. 245-250 one time going up a hill in traffic 105 degrees out. I almost pulled over at that point but killing the AC did the trick. I’ve never seen this truck past 215. Even in 80 degree weather coming back it was running 235 up the hill.

 

[Motor Boater]

230 is not hot, if that’s the real temp.

I read that towing up a grade 235 is normal for this engine but I’m babying it to stay at 235. I want to be able to push it. I don’t even use the tow haul button because it makes the motor run at such high rpm.

 

[RCDave]

235 seems hot to me. Water boils at 212. Yes antifreeze raises the boiling point but still...

 

[Bigbore500r]

First thing I’d do is hook a scanner up and see what the actual coolant temp is. The dash gauges are inaccurate. You may not have a problem at all, and are just seeing that the motor under load is finally making the gauge move off that “210” spot it is always parked at. If you hook it up to a scanner you will see that the temp actually varies quite a bit while the gauge doesn’t really move in accordance.

I’d start there before freaking out and throwing cash at anything

 

[srttruck]

I have the same engine in my jeep (aluminum block), 219-230 is my normal temp range. These engines like to run a bit warmer. Disclaimer: I'm no mechanic, I just know how to break stuff

 

[bk2drvr]

230 is not hot, if that’s the real temp.

Hotter than I like. The trans and coolant temp run about in parallel on mine. Even not towing I see the temps climb that high over steep grades. The goal would be to keep it around 200 always. There are some pretty nice drop in cooling options available. The all aluminum multi row radiators are really nice but pricey ~$800 if I recall correctly. Also some nice big trans coolers available that will knock temps down 20-30 degrees.

 

[Baja 252]

My 6.2 has 113,000 miles and the gauge is always solid on 210, doesn't matter if I’m towing, or if it’s winter or summer. Because its always on 210, I think the cooling system is good at handling any heat the 6.2 makes, its the thermostat that is holding it 210.
I bet you have a thermostat or air flow issue.

 

[LargeOrangeFont]

My Denali has the 6.2. I love this engine and it has always been a beast towing my 24 wakeboat until last weekend. All the sudden this thing is heating up. If I turn off the AC it cools down. Does the compressor have that much drag? Or maybe it’s going bad? The truck has 100,000 miles on it so it’s probably due for a coolent flush, plugs etc. any other thoughts or common issues with these motors?

Maintain your broken truck

Flush the coolant, change the thermostat and the water pump, change the plugs and wires. Clean out the radiator fins and make sure all the front underbody plastic and ducting is intact.

 

[bk2drvr]

Maintain your broken truck

Flush the coolant, change the thermostat and the water pump, change the plugs and wires. Clean out the radiator fins and make sure all the front underbody plastic and ducting is intact.

Some good advice here. I had a truck once that I drove to the river a lot (and I mean a lot) that started over heating. I pulled the radiator out and replaced it and when I looked at the one I took out over half the radiator was impacted with sand. I couldn’t believe what I was looking at. There was little air passing through it. I had already bought the new radiator but I could have probably just cleaned it out and it would have cooled just fine again.

 

[Motor Boater]

Maintain your broken truck

Flush the coolant, change the thermostat and the water pump, change the plugs and wires. Clean out the radiator fins and make sure all the front underbody plastic and ducting is intact.

This is kinda my thought. At 100,000 this thing has served me well and deserves some love anyway. Just curious if these motors have any specific gremlins that need fixing. I’ve also thought about switching to a high mileage synthetic.

 

[DRYHEAT]

Some good advice here. I had a truck once that I drove to the river a lot (and I mean a lot) that started over heating. I pulled the radiator out and replaced it and when I looked at the one I took out over half the radiator was impacted with sand. I couldn’t believe what I was looking at. There was little air passing through it. I had already bought the new radiator but I could have probably just cleaned it out and it would have cooled just fine again.

^^^^^ this

Probably one of the most overlooked things in cooling system efficiency the amount of dirt and bugs and shit that gets packed in between the fins.

 

[Howardflat]

a friend here on the boards had a similar issue with his duramax. He inspected the radiator and with all the years of driving the radiator was plugged with bugs and what not. took him a while but cleaned the radiator out and fixed it. Id take a peak there first.

 

[Taboma]

How much radiator surface area is covered in dead butterflys and bugs from years of river trips ?

Fuckin Ford really screwed the pooch ---- AGAIN --- when I raised the hood on my previous 12' Platinum, the grille raised as well, exposing the AC, Radiator and Intercooler fins. Piece of cake to keep them bug free from our spring Havasu trips.
Now with my 18' Raptor, they returned to a fixed grille and marketing bested engineering, demanding the centered license plate which nicely blocks the intercooler.
Versus the offset plate on my 12'.
Of course they addressed the centered license plate issue in the supplement --- just remove it when offroading ---- oh for fucks sake

 

[Riverbottom]

I live in the desert, and find that air flow is usually the problem. The fins on the aluminum A/C condenser and radiator are really tight, and can get plugged up with road dirt, bugs etc. About every three years, I have to remove the radiator, wash out the fins on the a/c condenser and radiator and reinstall. Even if the front of the A/C condenser looks pretty clean, I have found that the cooling fan has pulled leaves and road debris up between the condenser and radiator. The temp usually drops 20* or more after washing. Disclaimer : I am a mechanic and drive G.M trucks about 30K miles per year in the desert heat.

 

[pwerwagn]

235 seems hot to me. Water boils at 212. Yes antifreeze raises the boiling point but still...

Most 6.2’s have a 15 psi cap. At ~30 psi absolute, water boils around 250 degrees. Antifreeze mixed 50/50 with water at sea level is 230-235 ish. I don’t recall the curve of antifreeze, but if it’s remotely comparable to water, coolant shouldn’t boil till 260+.


My 6.2 Escalade doesn’t even tell me a temp. It has a gauge in the dash that is more useless than the stupid fuckin square clock caddy loves to put in everything.

 

[Flying_Lavey]

235 degree if I was careful in the hills. 245-250 one time going up a hill in traffic 105 degrees out. I almost pulled over at that point but killing the AC did the trick. I’ve never seen this truck past 215. Even in 80 degree weather coming back it was running 235 up the hill.

Have you looked at the radiator and condenser to see what condition the final are in? You'd be surprised how much junk gets built up on the front ends of these trucks.

You could also try adding an auxiliary trans cooler on it. Take some of theheat load off the radiator and out of the coolant.

Also, the thermostat MAY be hanging and not fully opening.

Sent from my LM-G710VM using Tapatalk

 

[pronstar]

Assuming you’re within weight limits...any modern vehicle that overheats based on AC use has an issue.

Even if it’s working hard in the heat towing uphill.

235 seems hot to me. Water boils at 212. Yes antifreeze raises the boiling point but still...

212 degrees is meaningless in a pressurized system [emoji106]

Reduce the pressure and you can boil water at room temperature.




Sent from my iPhone using Tapatalk Pro

 

[monkeyswrench]

My 2cents...
Make sure radiator is clear, no horse hair and bugs between condenser and rad. No winch of daylighters in front of grille, etc..

Make sure the electric fans are on...fuse or relay could be bad if it has multiple fan control, meaning one works when needed, but the one for ac heat transfer may not be.

Also make sure nobody removed lower "skid plate" for service. The plastic between core support and front crossmember. Seen as much as a 10* spike just from that.

 

[707dog]

got a esv with the 6.2L while you're screwing around under the hood add a nice big trans cooler inline with the stock crap your trans will thank you. added one after getting a bigger heavier boat knocked temps down 30 degrees on grades and long hills i kill the AC helps with the engine temps

 

[redone76]

got a esv with the 6.2L while you're screwing around under the hood add a nice big trans cooler inline with the stock crap your trans will thank you. added one after getting a bigger heavier boat knocked temps down 30 degrees on grades and long hills i kill the AC helps with the engine temps

I’ve been thinking of adding an additional trans cooler to my truck. Which one did you go with?


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[Bigbore500r]

I’ve been thinking of adding an additional trans cooler to my truck. Which one did you go with?


Sent from my iPhone using Tapatalk

The 40k GVWR Tru-Cool is a solid unit. Obviously overkill but it knocks the temps down very well. Universal fit, you may need a few adaptor fittings to get it to mate to your factory quick-disconnect trans lines.

https://www.amazon.com/Tru-Cool-LPD4739-4739-Pressure-Transmission/dp/B00803CTDA

 

[707dog]

I’ve been thinking of adding an additional trans cooler to my truck. Which one did you go with?


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went with a class 4 derale have to see what model # it fit right in the location opposite side of the factory one i ran them inline with each other. got it from etrailers.com

 

[DoughBallin14]

Only issue i have ever known with the 6.2 motors is that the lifters can fail and or bend pushrods at any mileage because of their AFM (active fuel management) program , basically 4 cylinder deactivation, i know there is a tech bulletin about it and warranty jobs have covered it typically. Otherwise cost is over 3k for the job to be done. All starts with a good bit of lifter ticking then thats a sign. Thumbs up on the cleaning up the radiator. Do mine every year on the duramax and always surprises me what comes out.

 

[BajaMike]

If it has the towing package it has a transmission cooler, if not, add one. I have a Chev 6.0 2500 HD crew cab with a 4.10 rear end.

If you don’t have the 4.10 rear end, make sure to down shift out of overdrive on hills, towing and hot days.

I have never seen temps over 200 on the trans or the engine. I replaced the radiator and a/c condenser at about 120k miles. I now have 180k miles, and towing up and down hills in the desert at 110 degrees outside, never have seen a temp over 200.

Towing up hills on a hot day in overdrive will heat up any engine......downshift and give your engine and transmission a break. Lugging an engine hurts everything in the truck.

 

[Fun Times]

AFM (active fuel management) program, basically 4 cylinder deactivation.

Quick note regarding GM engines with Active Fuel Management systems..: Be sure to replace the little oil filter screen found under the oil sending unit as it gets clogged up and causes major internal issues.

If equipped with active fuel management perform the following step, using J 41712 oil pressure switch socket or equivalent, remove the oil pressure sensor (706) and washer (707).
Remove and discard oil pressure sensor filter (452).

 

[CJ_Donahue]

The 40k GVWR Tru-Cool is a solid unit. Obviously overkill but it knocks the temps down very well. Universal fit, you may need a few adaptor fittings to get it to mate to your factory quick-disconnect trans lines.

https://www.amazon.com/Tru-Cool-LPD4739-4739-Pressure-Transmission/dp/B00803CTDA

I went with the Tru-Cool 30,000 just because both inlets were on the same size and thus easier to mount. The 30K was more than enough for me.

 

[SBMech]

I'd clean the radiator and condenser first, at 100k you should tune it and do a Thermostat anyhow, covers the flush.

Don't take it out of tow mode, it's there to keep it out of overdrive and to keep the engine in it's power band and to keep the trans from slipping...slipping generates heat.

When was the last time you serviced the trans?

 

[DaveH]

what number the gauge reads doesnt really mean all that much. the fact that you now see it heating up when it previously didnt...to me that is the concern.

some have said clean your radiator....and this is definitely a known issue with these trucks. its probably your AC condenser IN FRONT of your radiator that is all clogged up with years of bugs and road debris that limits flow to the radiator.

I'll go further and say that a good scrubbing of BOTH the condenser and radiator will fix your issue and probably make your AC blow colder as well.

For the people that only drive in CA or the desert this isnt as big of an issue. but of you drive further out where they have REAL bugs in cow country...this year with all the moisture we received has been especially bad.

 

[lbhsbz]

If it has the towing package it has a transmission cooler, if not, add one. I have a Chev 6.0 2500 HD crew cab with a 4.10 rear end.

If you don’t have the 4.10 rear end, make sure to down shift out of overdrive on hills, towing and hot days.

I have never seen temps over 200 on the trans or the engine. I replaced the radiator and a/c condenser at about 120k miles. I now have 180k miles, and towing up and down hills in the desert at 110 degrees outside, never have seen a temp over 200.

Towing up hills on a hot day in overdrive will heat up any engine......downshift and give your engine and transmission a break. Lugging an engine hurts everything in the truck.

My 2002 chevy 6.0 coolant temp gauge doesn't move...stays right at 190ish....but if I plug in a scan tool I've seen 247° on the ECT. Don't trust the gauge.

 

[white tortilla]

6.2 Issues?? where do I start! That motor is badass but mines been all but a lemon. 8speed tranny sucks, shifts hard and studders all the time now at 100k. AC condenser cracked at 50k, broke a lifter bent a valve at 75k, cam bearings went out at 105k needed whole top end redone. I do like smoking every asshole who drives a dodge challenger at the freeway on ramps though.

 

[redone76]

The 40k GVWR Tru-Cool is a solid unit. Obviously overkill but it knocks the temps down very well. Universal fit, you may need a few adaptor fittings to get it to mate to your factory quick-disconnect trans lines.

https://www.amazon.com/Tru-Cool-LPD4739-4739-Pressure-Transmission/dp/B00803CTDA

@Bigbore500r I have a question regarding installation of this trans cooler. I've seen some people have replaced the factory cooler with the tru-cool unit or just installed it in line with the factory system. What's your opinion?

 

[575cat]

Its amazing the garbage that gets through the condenser & wads up the the radiator , nobody ever checks .

 

[lake p.a.l.]

Its amazing the garbage that gets through the condenser & wads up the the radiator , nobody ever checks .

I'd like to learn what is supposed to be done?

 

[redone76]

I'd like to learn what is supposed to be done?

We pulled the radiator on my buddies truck while doing the AFM delete. Set it on a workbench outside and hit it with compressed air at about 120 psi. I have a rubber tipped blow nozzle so I couldn't hurt the fins. It was amazing how much crap came out of the radiator fins. Dust and dirt for days! He has over 200k on his truck. Plan on pulling mine and doing the same. Also installing the trans cooler

 

[Bigbore500r]

@Bigbore500r I have a question regarding installation of this trans cooler. I've seen some people have replaced the factory cooler with the tru-cool unit or just installed it in line with the factory system. What's your opinion?

The unit is so big, that i bypass the factory cooler completely and just run the tru-cool. On top of this cooling the trans doewn, this also takes any heat that the trans may be creating 100% out of the radiator and frees up that cooling capacity for the engine.

The concern people have in doing this, is that at low speeds it is thought the air / air coolers are ineffective and thats where you need the factory trans cooler which is water / air. The tru-cool unit is big enough that it doesn't create that concern, one you install one the trans temps drop dramatically at all speeds and you can verify with a trans temp gauge.

 

[redone76]

The unit is so big, that i bypass the factory cooler completely and just run the tru-cool. On top of this cooling the trans doewn, this also takes any heat that the trans may be creating 100% out of the radiator and frees up that cooling capacity for the engine.

The concern people have in doing this, is that at low speeds it is thought the air / air coolers are ineffective and thats where you need the factory trans cooler which is water / air. The tru-cool unit is big enough that it doesn't create that concern, one you install one the trans temps drop dramatically at all speeds and you can verify with a trans temp gauge.

Thanks for your input bud! I didn't even think about bypassing the cooler in the radiator. I was thinking about the factory external cooler from the tow package

 

[Bigbore500r]

Thanks for your input bud! I didn't even think about bypassing the cooler in the radiator. I was thinking about the factory external cooler from the tow package

Oh the factory one, yes i'd bypass that and just run the big trucool unit.

 

[LargeOrangeFont]

The unit is so big, that i bypass the factory cooler completely and just run the tru-cool. On top of this cooling the trans doewn, this also takes any heat that the trans may be creating 100% out of the radiator and frees up that cooling capacity for the engine.

The concern people have in doing this, is that at low speeds it is thought the air / air coolers are ineffective and thats where you need the factory trans cooler which is water / air. The tru-cool unit is big enough that it doesn't create that concern, one you install one the trans temps drop dramatically at all speeds and you can verify with a trans temp gauge.

This unit appears to come with a thermostat, you use that as well when installing it standalone, correct?

 

[Bigbore500r]

This unit appears to come with a thermostat, you use that as well when installing it standalone, correct?

I don't on my personal stuff because I'm in So-cal and dont go play in the snow, but it might not be a bad idea to use the model that comes with the thermostat if you drive in colder areas. I think they call it a "cold weather bypass", that model cooler has a different model number and includes that extra part in the hardware

 

[LargeOrangeFont]

I don't on my personal stuff because I'm in So-cal and dont go play in the snow, but it might not be a bad idea to use the model that comes with the thermostat if you drive in colder areas. I think they call it a "cold weather bypass", that model cooler has a different model number and includes that extra part in the hardware

Looking at the one you linked, it seems to have it in there. My thought was to not use it as well, but was wondering about your experience. Using it I'd have no worries at all though. Thinking of throwing one on the F150.

https://www.amazon.com/dp/B00803CTDA/?coliid=IGT91Z1QLESGC&colid=3KSJMVOOUXFDQ&psc=1

 

[bk2drvr]

Another option other than the Tru-Cool is the Mishimoto unit. It's expensive but I like how they've designed the mounting scheme for you and supply lines to connect to your existing cooler.

https://www.mishimoto.com/engineering/2019/01/chevrolet-silverado-2014-transmission-cooler-rd-pt3/

 

[boatpi]

What are you guys running for oil pressure, mine gets down to about 25 pounds on idle once it’s warm?

 

[dribble]

235 seems hot to me. Water boils at 212. Yes antifreeze raises the boiling point but still...

Water doesn’t boil at 212 when it’s at 15psi.

 

[redone76]

What are you guys running for oil pressure, mine gets down to about 25 pounds on idle once it’s warm?

Oil pressure on mine when warm is around 40 psi. Cold it can get to 20 psi but climbs up as it warms. 155k on my '08
On my buddies truck it would stick an AFM lifter when cold and his pressure was around 10 psi. Once the lifter unstuck it would climb up to 40 and stay

 

[Bigbore500r]

Oil pressure on mine when warm is around 40 psi. Cold it can get to 20 psi but climbs up as it warms. 155k on my '08
On my buddies truck it would stick an AFM lifter when cold and his pressure was around 10 psi. Once the lifter unstuck it would climb up to 40 and stay

You have a failing oil pump pickup o-ring. When the oil pressure is higher when warm at idle that it is cold, it is because the O-ring is allowing the pump to suck air, and it's easier to stuck air than oil when the oil is cold and thick. As the oil warms up, it becomes easier for the pump to injest on the suction side and that reduces the tendancy to suck air past the failing O-ring.

 

[BajaMike]

Does it have a 4.10 rear end.....if not that part of the problem. I would replace the radiator and the A/C condenser/ and the transmission cooler. And if it’s not a 4.10 rear end, always downshift when towing.