PCV Milkshake-Rusty oil dip stick

[SoCalSlaughter]

Truck is a 90 Suburban 5.7. About a month ago I went to check the oil, and noticed the top of the oil dip stick (Closest to handle) had rust on it. Oil is clean and full. Removed oil fill cap and its clean. Removed the air cleaner assembly and noticed where the fresh air tube comes in from the valve cover had a milk shake residue on it, also alittle bit on the throttle body itself. Coolant is full and green. Truck doesn't over heat. Replaced intake manifold gaskets to see if that would fix the problem. But after a few weeks the oil dip will get rusty again and the milk shake residue will slowly come back through the fresh air tube from the valve cover into the back of the TBI. Note, I dont make short trips in the truck. Work is about 15 minutes away, mostly freeway. Anything I should check for? Thanks in advance.

[crazy longhorn]

It sounds like you are looking at it right on.....no issues in the oil? I dont know your location, but will ask.....is it very humid where you are? Longhorn

[cadillac_al]

Somebody probably put a colder thermostat in it.

[Dead Parrot]

2nd the thought on the thermostat. Should be a 195. Also, a 15 minute drive, even mostly freeway, is a short trip. It is just getting hot when you stop it. Perfect setup for blow by buildup in the oil. You want the oil to get hotter then 212 so any water in the oil boils away.

Make sure the PCV valve is working and the vacuum port for it isn't plugged.

[SoCalSlaughter]

Truck has a 195 Thermo in it. I removed the PCV from the truck the other night and its free (Rattles). Tried to blow and suck though the PCV and it allows air in both directions. Its currently raining here, so Ill check the vac port on the TB this weekend to make sure its free.