Okay so kinda good news ....

Dealer tested the cooling system. No pressure spikes or leaks, so it's not getting pressurized from a blown head gasket or the EGR.

They also found the coolant leak ... they found two failed clamps on the radiator hoses, one on the upper hose at the radiator, and one on the bottom hose. They replaced them with the normal screw style hose clamps and problem solved.

The bad news ..... it's still overheating. This morning (about 47 degrees) it hit 215 at 72 MPH and then dropped to 183, which it should since I replaced the t-stat with a 180 back last year. They have another '08 or '09 in the shop with the very same issue and they're optimistic they can find out why.


It's back in the shop, but the hose clamps only cost me $38, parts and labor. I can't complain about that at all.


-Kris

I'm thinking that if you had leaks and things like this as well as previously replacing thermostat that maybe you have some air pocket in the system that needs to be purged...

Another update.

Dealer burped it via the exhaust coolant plug. Nothing but coolant so we should be good now, but we're not.

Temps are still hitting 215-220, and now the dealer has seen it. Tested fan clutch and it's engaging, and it's within 1000 RPM of spec so they're ruling out the fan/clutch. Coolant is moving through the system otherwise we wouldn't be seeing any temp drop, so they're ruling out the water pump. No weeping seen at the water pump either, but I might replace the plastic 7 blade version from the factory with a metal 7 blade aftermarket.

They're going to do a complete flush, put new coolant and some additive to remove any gunk from the cooling system. I might need to pick it up and drive it around for a bit to help it circulate the cleaning agent throughout the system.

Ugh.




-Kris

Within 1000rpm's? That's quite an allowance for a fan that at most turns as fast as the engine, no?

IIRC, fan speed should max at 4000 or 4500 RPM's so if it's within 1000 RPM's it should be fine.

I think I'm going to try the rag test when I pick it up today.



-Kris

i would check it with another gage

Did anyone test the radiator for blockage? Check for any cold spots on radiator telltale sign of blockage. Temps should be same across radiator after driving. Also anyone pull EGR cooler and check for leakage, I bench test easy to do, fill with water and then run regulated air pressure 20 PSI into coolant passage side, any air bubble into exhaust side is failed EGR cooler replace it.

Not yet, they're going to do the flush w/chemicals first to check to see if there is any scale or gunk and then move on with testing. I'm also replacing the thermostat, just in case, because they said it's only about 1/2 inch open.



-Kris

Flushed the cooling system and it helped.

3rd t-stat did the trick and it's running great. Picked up a 180 degree from a place online that could get it to me faster than Cummins could, and didn't cost me $68 for a $35 part from one of the local dealers.




-Kris