volvo d12 fuel mixing with coolant

I had a same problem on Davco water separator, it has a fuel heater that leaks coolant into fuel. You can replace bottom part of the separator or the whole thing.

 

the D series from Volvo was it not plagued with Injector cup issues also ?

 

Injector cups usually

 

Not sure how bad cups would cause coolant in the filter. I would expect to find fuel in the coolant reservoir. Fuel is at a higher pressure than coolant. I agree with checking the filter housing first if it does use coolant to hear the fuel.

 

Cups maybe.. But check to see if you have coolant lines running to your fuel tanks. Truck may have a fuel tank warmer and I've seen those go bad. Just a quick bypass hope this helps. Good luck