C12 cat. Engine coolant leaking into engine

I had this issue with a C12 in a 387 Pete. It was the head gasket. I was told it was a common problem with the C12.

 

Could also be the dreaded bad liner seal. Just inframed a 3406C model. #1 liner had a broken liner o ring. Hope this is not your case.

 

Just wanted to reply.... My problem ended up being my head gasket went bad. I had 1.2 million so at that point I decided to go with an inframe. I had my head checked by Cat to see if I could use it again or had to get a reman. Under testing they found two cracks so that could have contributed to the water lose as well. Either way it is fixed now.

 

Had my cat rebuilt by peterbuilt, ran great ,then started loosing coolant & running hot, took it to caterpillar in Bradenton, Fl. they replaced head gasket under warranty, that didn't fix it,2nd time they replaced two thermostats & ran on dino,that didn't fix it(no warranty) .3rd time they replaced liner & ran on dino,that didn't fix it 4th time replaced head & ran on dino,that didn't fix it,5th time replaced inner cooler & ran on dino,that didn't fix it,replaced temperature gauge,didn't help,took it back to caterpillar they test drove it & said it didn't get but 200 degrees and there is nothing wrong with the truck.I still put a gallon of coolant every 1500 miles & temperture gets to 225 degrees.No more warranty ,any suggestions??

 

I am getting mine pressure tested but not for another full week. They have already been mixing for 2 weeks and getting worse. Put a gallon in yesterday.

I was thinking doing what you said could be a good idea to keep the amount of water/antifreeze in the oil at a more reasonable level meanwhile?

 

Water pump it was for me, thank God!

 

wow! please update. Have you fixed the problem or you still running at gallon of coolant every 1500mi. I am trying to fix my coolant loss issue. Having mixed results with coolant sealants. Still confused as per exact cause but not willing to let anyone rip into my engine just yet...

 

did the oil look milky? have you done oil analysis? How much sodium was in the oil? Thanks

 

what year is your engine? At some point Cat started using CGI (Compacted Graphite Iron) material for engine heads. I think around year 2000 is when it happened. The CGI heads supposedly are much more resistant to cracks than the older tech...

 

if its anything other than the engine, bars iron color stop leak shouldnt help cause its specifically for engine leaks. I think it like seals only at super high temps in engine cracks and such. You should have tried radiator coolant sealant as well, cause that stuff seals leaks outside of the engine (like heater core and compressor gasket and such)...
Did you find what the problem with your engine was? Thanks