Coolant on oil cap?

[therieldeal]

I've been working on cars for years now, and this has me stumped.

 

2005 LGT, 205k miles. Just bought it recently from the original owner. I repaired a minor coolant leak right after i got it (small hose that connects to turbo dripping onto up pipe). I also changed the oil, and didn't notice anything obviously wrong aside aside from a rusty/seeping oil pan. The oil i drained out looked normal.

 

Drove it a few hundred miles... no coolant loss. I was checking it regularly since I'd just fixed that small leak and burped the system. Noticed it was misfiring at high RPM... replaced the spark plugs (they were worn and gap was huge, 0.045"). Still missing... started checking for vacuum leaks and found several, the crappy cracked turbo inlet hose being the most worrisome. That day I also noticed that it has a chinese turbo on it. At this point I parked it and started looking for a used genuine IHI VF40 and ordering the other parts I need.

 

Today it was somewhat warm out so I was futzing around, swapping my cracked grille for a less-cracked one. Checked the oil, looked normal, just a touch low. Take the oil cap off to top it off... and there is a green liquid on the oil cap threads? It's bright green... coolant for sure. No brownish "milkshake" sludge on the underside of the cap like I've seen before on other cars with blown HG's. Pull the dipstick again, wipe it on a paper towel this time... looks like oil, no milkshake appearance. Check the coolant overflow... normal looking coolant, no signs of oil mixing that i can see. Stumped...

 

The heads were rebuilt & new head gaskets installed (obviously) at around 160k due to burnt exhaust valves, this was done at a dealership. Given that they are only ~50k old it seems unlikely that it's a head gasket problem. Where else on these engines could a small amount of coolant be getting into the oil? I'm thinking the chinese turbo could be the culprit, anyone ever have that problem? Maybe the oil cooler? I'm thinking my best course of action is going to be to proceed with my plan to replace the turbo and other misc items and refill with fresh oil, and then see what happens. Thoughts? Suggestions?

 

My full to-do list is:

Turbo inlet hose (silicone)

Oil pan (used '11 wrx)

Catless up pipe (stock sti)

Downpipe (used cobb)

Turbo (used ihi vf40)

Fuel rails (used, mine are rusty and look a little sketchy)

Injector seals

Intake manifold & throttle body gaskets (signs of vacuum leaks, at the tb especially)

PCV valve (why not? it's buried under the intake manifold after all)

Inspect all vacuum lines that live under the intake manifold

Timing belt kit, water pump

 

TL : DR - There's coolant on my oil cap threads. Everything else seems for the most part normal. HG's are fairly new. Other than HG's, how/where is coolant and oil likely to mix on these motors?

[therieldeal]

Talked with a friend of mine who used to work at a popular speed shop in Orlando (he's an engine builder & tuner).

 

He's seen Chinese turbos cause coolant in oil problems on several occasions. In fact it has been such an common problem that whenever a customer insists on using a Chinese turbo he actually bypasses the coolant connections to the turbo and plugs the coolant ports in the CHRA with bolts.

 

This makes me feel a bit better. His recommendation was to proceed as planned with replacing the turbo, fresh oil, etc. Just figured I'd share this info in case it might help someone else.