Overheating -

[Keith Seymore]

Just got back from my first race trip, this one in Atlanta.

I drove through the night Thursday night, hitting the city around 8 or 9 am. My truck was running hot, like 250 deg, pulling the grades into and out of Atlanta. We limped it to the track, in Commerce, about 10 am. Ambient temp was about 77 deg, so not terribly hot.

I'm looking for suggestions on a potential root cause and solutions.

We were able to make it home by turning off the AC and turning on the heat full blast. Actually - we could pretty much control the engine temp by playing with the heater, and kept it solidly at about 210 deg once we made that discovery. As Sunday evening wore on the ambient temps dropped and the ground leveled out so by the time we hit Cincinatah it was about 52 deg and we were home free.

By way of reminder, it's an '04 2500HD with the 6.6 Duramax (LB7) and 3.73 gears. Trailer weighs about 7500 lbs with the car in it.

Thanks,

K

[hatzie]

Maybe you've seen this. Apparently the cooling fan can push an abnormal amount of hot air into the air filter intake area.
http://www.maxxtorque.com/2008/07/du...ution-and.html

This is the service bulletin 06-06-04-036D he references with the GM factory cold air intake arrangement.
http://ww2.justanswer.com/uploads/je...verheating.pdf

[Keith Seymore]

Thank you; I'm going to make sure that the radiator fins are clean and not damaged, and then fabricate a cold air intake duct.

K

[Boog]

How long have you owned and towed with that truck? If you've had it for some years and overheating is just now happening I don't believe it's a cold air intake issue. Fan clutch, thermostat and plugged radiator top the list of possible culprits.

[Keith Seymore]

Good point. I've had it since Nov of 2015.

K

[hatzie]

I read that it was your first trip with it and assumed it was a new acquisition.
Forgot my first rule. Never assume

No problem til you started towing?
Do you have any extra gauges like EGT for instance?

[Keith Seymore]

Truck update - the whole front of the radiator is covered with oily fuzz, like from a cottonwood tree.

?????

Not sure why it would be on the radiator rather than the forwardmost heat exchanger (AC, or charge air cooler).

Now I gotta figure out how to get it off there without damaging the fins.

K

[Keith Seymore]

Originally Posted by hatzie

I read that it was your first trip with it and assumed it was a new acquisition.
Forgot my first rule. Never assume

No problem til you started towing?
Do you have any extra gauges like EGT for instance?

Thanks, Hatzie. First trip this season. It was running 210 empty and didn't get worked hard til I put the trailer on.

No extra guages, just factory.

[v30crewcab]

feel the radiator top and bottom with it warm, if the rad is starting to plug up, it will be hot on the top and colder on the bottom.

[hatzie]

Originally Posted by v30crewcab

feel the radiator top and bottom with it warm, if the rad is starting to plug up, it will be hot on the top and colder on the bottom.

The whole point of the radiator is to make the water going back into the engine colder than the stuff that's coming out of the engine.

I'd get worried when the water coming in the top is the same temp as or within a handful of degrees of the water going back into the engine.

The fluffy oily crud in the fins would reduce the coolilng efficiency of the radiator a whole bunch.

Keith,
Do you have a tiny leak in an engine-oil/transmission cooler or cooler hose or the AC condenser that's misting a tiny amount of oil into the cooling stack so the radiator is collecting that fluffy crud?

I assume the charge air cooler is the leading edge of the cooling stack, then the oil coolers, AC condenser, and finally the radiator.

I've had a charge air hose leak blow oil mist into the engine compartment on my 05 Jetta TDI.

[Keith Seymore]

Originally Posted by hatzie

Keith,
Do you have a tiny leak in an engine-oil/transmission cooler or cooler hose or the AC condenser that's misting a tiny amount of oil into the cooling stack so the radiator is collecting that fluffy crud?

I've made an oily mess on a couple occasions (my own fault) but I think that is behind me now.

Originally Posted by hatzie

I assume the charge air cooler is the leading edge of the cooling stack, then the oil coolers, AC condenser, and finally the radiator.

It goes AC condenser, CAD, then radiator.

One other point: this issue may have been brewing for a couple years. I was remembering that I would lose AC cooling while stopped for red lights and such, and then it occurred to me that I didn't do any trailering last year due to the pandemic.

I was able to clean all the fuzz off the face of the radiator by laying it back (without completely removing it) and spraying the leading side with brake clean and the garden hose.

I'm optimistic that this is going to take care of both my problems (although....it's 32 degrees out there right now).

K

[v30crewcab]

trust me this works. been using this trick for 30 years to identify plugged radiators.

Originally Posted by hatzie

The whole point of the radiator is to make the water going back into the engine colder than the stuff that's coming out of the engine.

I'd get worried when the water coming in the top is the same temp as or within a handful of degrees of the water going back into the engine.

The fluffy oily crud in the fins would reduce the coolilng efficiency of the radiator a whole bunch.

Keith,
Do you have a tiny leak in an engine-oil/transmission cooler or cooler hose or the AC condenser that's misting a tiny amount of oil into the cooling stack so the radiator is collecting that fluffy crud?

I assume the charge air cooler is the leading edge of the cooling stack, then the oil coolers, AC condenser, and finally the radiator.

I've had a charge air hose leak blow oil mist into the engine compartment on my 05 Jetta TDI.

[hatzie]

If a large section is completely or mostly plugged up it'll be stone cold or very close to that over the affected area. I would guess you could pick that out with a FLIR camera fairly easily. One of the nice things about that kind of tech getting to be more accessible in price.

Mildly restricted flow is a bit more difficult. Experience would make you better able to judge but most of us don't see that kind of problem because we use distilled water rather than tap water so we don't get the calcium deposits and heavy internal corrosion in modern vehicles that we used to see in the '70s & '80s.

[Keith Seymore]

Just checking back in to say that the fuzz removal process fixed it.

Towed to St Louis and back with no issues.

Oh - and:

[Palf70Step]

Good to hear it Keith