can a oil catch can have vacuum on it...? (both valve covers vented under the truck, not back to intake) i put it on a couple of weeks ago and today i looked like it had some water in it. i put a cup under it and pulled the plug. almost a Pt of water came out, NO oil. i pulled my dip stick and it was milk ! it doesnt have a miss and its not smoking or over heating so i really dont think its a head gasket.


i did wash under my hood last night but not under high pressure and i was really only spraying the frame rails and inner finders. any way i could have got this much water in my oil some how ?

i dont have time to do anything ab it right now im off to work in OK for the week. it will be parked until thursday night when i get in. any ideas on what it could be. thanks

 

How much boost you pushing? Sounds like you're pushing water. But change your oil, check your coolent over flow and mark it. Might be time for sum studs and head gaskets.

Water in the crank case will steam out and collect in the catch can, as the vapors are pulled through by vaccume.

 

ya i keep thinking about it and i realized that the catch can was doing it job as you said. its the stock whipple 4in pulley. ab 7-8lb max but iv not even been hard on it. i think im going to just order the stuff to do a budget build on my 99 4.8 and put it back in

 

That was my first thought also, that your lifting the head, pushing water. But I do not think I have ever heard of that on such low boost. I will change the oil, see if it goes away( prob not) but it could be a possible you got water in there from squirting it with the hose, possibly through the dip stick hole in the block.

 

thats what im going to do. maybe it will go away but im ordering everything right now so if it is a head gasket iv go a rebuilt motor to just drop in.

 

update. got home and checked all my plugs and everything looked good. still looked to have water in oil so picked up a cheap change and filter and a good one. when i pulled the plug... it looked fine going to run it for a day and see if anything changes.

i dont know why but for some reason im thinking my oil catch can did have something to do with it. took it off now to see if the problem comes back.

 

What heads are you running on the 4.8? Sounds like it's pushing water. Is your coolant reservoir turning color from white, to black-ish?

 

being its a early model i wonder if it has the castech heads and hairline crack??HMM

 

His sig says 07 4.8, but I just wondered the same thing. Maybe he put his old heads on the shortblock? But I don't know.

 

If you have the ability to pressurize the coolant system I would do that in the middle of the oil change.