Overheating & Combustion Gas in Coolant - Head Gasket or EGR?

[DC3]

I’m afraid the answer to my question might be obvious (head gasket leak), but I’m hoping to get some input from others who’ve been through something similar.


My 2021 EcoDiesel Gladiator has about 44k miles. Last year, around 35k, the dealer replaced my EGR cooler due to coolant consumption. A few thousand miles after the replacement, while towing on a flat road under light load, I experienced a sudden coolant temperature spike. I immediately pulled over, found the coolant low, and had it towed to the nearest dealer. They topped it off and sent me on my way. I chalked it up to air not being purged properly during the EGR cooler replacement.


I didn’t have further overheating issues the rest of last year. But now, this year while towing again, I’m seeing similar temperature spikes.


Here’s what happens:

• Coolant temp climbs to ~235°F, then rapidly spikes to redline.
• I immediately coast to the berm and let the truck idle.
• After about a minute, temps drop back to normal.

I replaced the thermostat hoping for an easy fix, but no change. I also used a block test kit, and unfortunately, I did detect combustion gas in the coolant.


My questions for the group:

• Has anyone else dealt with this?
• What ended up being your root cause and resolution?
• Am I crazy to think the EGR cooler might still be the culprit, even after replacement?

Appreciate any insight!

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[rharr]

You can try a leak down test to get more specific answers. The fluid test is a good first start test. Leak down will give you real data.

 

[DylanM]

Given the operating pressures of the cooling system, EGR, and the cylinders, I'd say the most likely source of the combustion gasses would be from the cylinders either via a bad head gasket or a crack. Either way, this should still be covered under the powertrain warranty so a talk with a dealership would be my recommended next step... unless of course there's reason for you to work on it yourself.

 

[rharr]

my advice, get a leak down test done at an independent shop, take the results to a dealer and the shops invoice and present them with the results if it shows a failure. That will give them someplace to start and they will likely perform their own test to confirm. Otherwise they will just dick you around until you give up. They don't want to do a head job on a eco d when they have no eco d techs...

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