ISX CM871 Oil In Coolant

Hi guys. Just recently started getting a skim of oil in my surge tank. Coolant hoses are now getting soft and sweating an oily residue. Everything seems to point towards the oil cooler. My question is: How do you verify it is in fact the oil cooler? I was thinking of removing oil filter, then pressurizing the coolant system with air at the surge tank, looking for coolant loss from the oil filter head. Cross contamination could be coming from any number of areas: air compressor, turbo, water pump, head gasket etc. Any other suggestions towards testing would be appreciated. Would really suck to replace, then find out it's a head gasket.

 

Hi HeavyD. I made my own test plates and submerged in water with 100psi air pressure. No leak in element at all. The gaskets looked a little sketchy, so I’m hoping with all new gaskets, the leak is fixed. Any other suggestions what to look for, if this doesn’t correct the issue?

 

Hi HeavyD. Truck is back together, even painted all the components so it looks like a brand new engine (on one side! Lol!) Yes, it appears that it was only the element gaskets that failed. Thanks for the advice! Now a new problem. I had the fault code for throttle position sensor below limits, losing response. Just let off throttle for 5 seconds and power came back. It did this randomly several times, while under heavy boost. Then, problem went away. I bought whole new pedal (as the old one was pretty corroded.) Tried doing the 3 depression slowly calibration, but now have no throttle response and both check and stop engine lights on. I had several faults on dash that disappeared, and now says “ no faults”. What’s going on here?