Hey Y'all I have oil coming up my dipstick and feel like it might be from a vacuum leak causing to much crankcase pressure. I've been trying to trace my vacuum lines to check for leaks but all I can seem to find is the line coming from the vacuum pump to the check valve at the brake booster but both ports on the check valve are capped off, do the vacuum lines continue through the firewall on the other side of the brake booster?
I've looked at the vacuum diagram for these trucks but it doesn't seem to help.

Thanks

 

What year is your truck?

My 89 has no vacuum lines going to the crankcase. My crankcase simply vents through a tube going down to under the truck.

Edwin

 

The vacuum pump on both Non-IC and IC trucks does not use and crankcase air to generate it's vacuum. The oil coming up your dipstick is caused by too much blow by in the motor, or a plugged crank case breather tube.

 

Edwin, it's a 93.

I've checked my crankcase breather tube, its fine.
From my understanding if there's a vacuum leak somewhere the vacuum pump vents into the crankcase. Is this incorrect? Though now that I'm thinking about it the only hose coming off the pump goes to a check valve...

 

I don't think it's a vacuum issue. Diesel filling the crankcase, Head gasket, or a blown cylinder would be my guesses.

Maybe drain it and see what comes out? If you've got over 3 gallons, its not all oil.

 

Sam,
Does the oil level on the dip stick return to normal after it sits for a while, or continues to rise higher after running it?
Does the engine run normal or rough?
White smoke, blue smoke from the exhaust?

 

I checked oil after driving around town for 20 minutes it was at full line on dipstick and checked again at home and it was midway on dipstick. Neither time was the truck parked perfectly flat, but was pretty close. Pretty good drip after driving around. A little bit of white smoke on first start of the day. Engine feels like its running good.

Thanks,

 

Is there any diesel fuel in the oil? Maybe the lift pump or front seal of ip is leaking fuel...Mark