Pam boles

I have a 2003 GMC Yukon XL with a 5.3 . I recently rebuild the motor installing all new parts , after driving less than 100 miles the intake has a lot of oil building up in it . Poor take off low oil pressure and rough idle . I have examined all pcv lines , new oil pickup tube seal . I am at a loss on what to do next other than tier it back apart . Any advise will help thank you

1FastBrick

iTrader: (17)

How about some more details on your issue? Poor take off, low oil pressure, and rough idle .
What is the oil pressure at idle?
You stated you rebuilt the engine with new parts? What was replaced and what machine work was done?

Have you verified the Compression in each cylinder?
Have you verified the Fuel Pressure?
Have you verified you have Spark at each cylinder and plug?

Pam boles

At idle it's running about 5 to 0 PSI then getting up to about 39 PSI while driving then after about 10-15 minutes of driving it'll drop back down between 15 to 20 psi while driving.
Have done compression test on all the cylinders only one of them seem to be a little low on compression and it's at a 155 the highest one is 185
All new parts except for the camshaft and pistons but we did put on new piston rings except from that everything was new.
There was no machine work done
The the whole motor was cleaned with a wire brush except for the Piston walls which didn't need to be
The Pistons the Piston walls and the crankshaft all look pristine the piston rings were all in good shape but we still put new ones on we made sure to scatter them out around it so the opening didn't meet up on any of the piston ring even went and bought a second set of new head gaskets thinking that that was the problem and change them again

1FastBrick

iTrader: (17)

When you replace the rings it's a good idea to hone the cylinders. This will help them break in and seal properly. It sounds like you have good compression though so this is likely not your issue.

As for the oil pressure issue. Did you use a new oil pump? Did you replace the little barbell in the rear of the engine?

Pam boles

We used a new oil pump did not change the barbell in the back of the engine the oil pressure filter there was no screen in or the guy that was working on it couldn't find it but he said there was not one and assumed that it didn't need one

1FastBrick

iTrader: (17)

Usually its recomended to change the barbel during a rebuild. The o-ring conforms to the shaft and becomes brittle similar to the pick up tube.

What about the front cam retainer plate? This seal also conforms to the block and becomes flat. It is also recomended to replace this part and this is another place you can bleed off pressure.

I suspect you either have a stuck bypass on the Oil pump or the new O-ring was torn during installation.

Pam boles

The retainer plate gasket was changed there was a new oil pump put on and a new o-ring we suspected it could have been the o-ring so we bought a new one and replace it again we checked it out over a few times and all seals are good nothing's leaking out of the motor other than the oil getting into the intake some out

1FastBrick

iTrader: (17)

So why was the engine rebuilt initially?

The oil could be coming from the PCV system and being sucked into the intake. Or it could also come from the valve seal if perhaps one was leaking on the intake side.
Not sure If the valve seals were replaced during the rebuild.

I would be concerned with such low oil pressure.

Pam boles

Bought a new PVC valve the one that came out of it was hollow didn't have a little shaking thing in it valve guide seals all bought new and replaced that's why we're so concerned is the low pressure whatever's causing low oil pressure is the reason why it's leaking into the intake just can't figure out what the cause is

1FastBrick

iTrader: (17)

Why was the engine rebuilt to begin with?