2019 International LT625 A26 Engine - Coolant in Oil

Question

Did my pre-trip today and noticed the oil level is high and the oil on the dipstick looks like a milkshake. I'm definitely getting coolant into the oil. The truck isn't overheating yet but I'm losing about a gallon of coolant every 1,000 miles.

I'm praying it's not a cracked head or a liner seal. The A26 is still relatively new to me so I'm not sure what the common failure points are for internal leaks. Has anybody seen oil cooler failures on these?

WrenchMonkey_J · Accepted Answer

✅ Confirmed fix: The issue was the air compressor head gasket. On the A26 (and many MAN-based designs), the air compressor is coolant-cooled and shares a return path.

When the gasket fails, the compressor pumps coolant directly into the crankcase. We replaced the air compressor and flushed the oil system three times to get the sludge out. Avoided a full engine rebuild by catching it early.

MisfireMatt · Answer

It's likely the oil cooler module. The gaskets on the A26 oil cooler are a known weak point. However, usually that puts oil into the coolant rather than coolant into the oil because oil pressure is higher. If it's coolant in the oil, check the water pump seal weep hole to see if it's plugged.

2019 International LT625 A26 Engine - Coolant in Oil

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