recently replaced engine.

[denalimike]

Had my engine replaced about 2 months ago or so. Well, since then I've had issues with smoke and hesitated starts. I knew I needed to replace the cats so I did so and while I took it back to have the guy look at it, we assumed the issue with the smoke and hesitated starts were the cats. replaced as well as replaced knock sensors because they were bad. O2 sensors were not bad according to the read out.
well, since then, I've had to refill/add oil (2 quarts each time) twice but I can't seem to see where the oil is going?!. nothing on the drive way or no burning smell as we drive it. finally today we noticed severe knocking and hesitation and the engine light came on, we had OnStar check it and they told me that it was a code P0300 and to take it in right away. I'd hate for this guy to tell me it's something that won't be covered but he seems like straight shooter. Any ideas what this could be specifically? btw, when he replaced the engine, there was a laundry list of things he did, eg, replace plugs and wires, replace hoses, send the radiator off to get flushed. so I can't think of anything he wouldn't be responsible for given that we drove it normally and didn't take it to the track.
any help is greatly appreciated.

 

[denalimike]

Spoke with mechanic, he states that where the valve cover is, there is normally a pcv valve that opens and closes with a spring which releases suction however on my truck there is only and indention. He states that what is happening is the oil is getting sucked into the intake manifold and is full of oil which I am burning little by little but is causing all this to happen. He states that he is going to add another valve cover which has a pcv valve to see if this fixes the problem. He told me that he did on 07 silverado recently that had the pcv valve and can’t understand why this Yukon doesn’t.

Anyone have issues with this or any insight as to if this is a good move?

 

[livingez_123]

the 6.0 has a small orifice in place of the valve. if you follow the hose from the throttle body to the valve cover you will see where it goes into the valve cover, if you pull the hose off at the valve cover you should be able to poke a small wire or WD40 line through the hole and into the valve cover, they do get blocked from time to time and just need to be cleaned. they can pull oil because there is no venting if the hole is plugged.

 

[denalimike]

good info to relate considering he seems to be boggled by the 6.0. would doing what he is attempting be an issue with the engine down the road or is it a alternative fix for the issue? thanks for your help.

 

[livingez_123]

the 6.0 by design has the orifice not a PCV, but some others have the valve. he needs to fix what the engine came with not try to solve it by adding one. they are designed for a reason not to have the PCV, not sure if it will affect the idle. does he know for a fact that the intake is full of oil? maybe he forgot to put on the valve stem seals. a simple test would be to put a temporary breather where you oil fill is. that will eliminate any pressure build up. I don't even see how you could be pumping oil into your intake. the intake is separate from the valley cover.

 

[denalimike]

did you mention that if its plugged it will pull oil. Where would Iit go? I may have been wrong on where he said the oil is, either the valve cover or intake manifold but I am sure that he said it gets pulled into the engine and eventually burns up that's why I have to keep putting oil in.

 

[livingez_123]

it could push the oil past the valve stem seals. Or another thing, if somehow a oil drain in the head got plugged and isn't allowing the oil to drain back into the engine. but if your building enough pressure in the block to force oil into the valve stem seals you would be blowing oil out the front and rear seals and maybe even the valve covers. The only way your going to fill up the intake with oil is if your pulling oil from the orifice into the TB and then intake. remove the hose on the back of the TB that goes to the valve cover and see if it's soaked with oil. if you do have excess crankcase pressure the rings aren't sealing correctly. pull the oil fill cap and run the engine and see if you have a bunch of vapor coming out of it.