7.3L Diesel in Coolant but NOT an injector cup - HELP

[93coupett]

What would cause a 7.3L get diesel in the coolant other than an injector cup being bad? We thought this was the problem so we replaced all the cups and injector o-rings and it still gets diesel in the coolant.

The truck does not even need to be running to get the diesel in the coolant. As soon as you turn the key and the fuel pump kicks on, the diesel starts running into the coolant lines.

What could this problem be? This is not my truck (friend of my dad's) but we are all stumped on what the problem could be. This guy had the engine replaced with a LKQ one but the shop didn't know what they were doing and after 3 months of trying, they gave up...couldn't even get the truck to start and they told him it never would.

My dad spent half a day fixing the shop's problem's and it started right up and runs really good. It just get's diesel in the coolant and we don't know why. Since this was a replacement motor, could the shop have forgot to install a seal or something? What other things could cause this? We are stumped. Please help.

[makey98]

resurrect this thread. i haven't replaced cups yet, but have same problem. runs great, but fuel in coolant.

[worthingtonmedic38]

Cracked heads, injector cups or seals?

[93coupett]

Originally Posted by makey98

resurrect this thread. i haven't replaced cups yet, but have same problem. runs great, but fuel in coolant.

Got this problem fixed. Solution: pulled every cup and re sealed them. Replaced all 0 - rings on the injectors. Found one 0 ring that was really chewed up. Put it back together and no coolant is leaking.

[worthingtonmedic38]

Good! I have had problems with injector seals before but it usually manifests itself by dumping all the engine oil back into the fuel tank, never personally had the other seal go out. Glad you got it fixed!