Burning oil - When Warm

[96AWD5.LOL]

Hi all,

I’ve got an odd issue with burning oil. The engine has been re-sealed and has new kings cylinder heads. There was a persisting oil leak around the oil pan and lower intake gasket after this but those have since been replaced and all corners are bone dry. It seems to puff oil when taking off from a light or after descending/coasting for a bit. There is no smoke while cruising or at cold start. PCV was replaced with a motorcraft with no change. Depending on the length of time under the extended vacuum dictates how much oil is burned. Yes, it’s blue smoke. You can smell it in the cab if there’s enough burned. I performed a compression test and all around I got 180x4-175x1-165x1. Performed the test twice on each cylinder. Tester used was the OTC 5606. Replacing the intake gasket after the intial reseal (gasket 1) was when the oil burning started. A different two piece (gasket 2) was used that time. I thought oil may be getting into the cylinders through the runners so I put the same Felpro one piece (gasket 3) back in and it still smokes. The spark plugs look new and and there is 0 oil on any of them. I’m not loosing coolant.

Engine has good power for a 4.0 4x4. There’s probably 2000 miles on it since the initial rebuild. The block had 141k on it at the time of reseal and you could still see the crosshatches.

I am stumped. It could be valve seals but I would wager that I would be seeing smoke on startup. And if it was rings I feel it would’ve shown in the compression test. There’s no oil in the intake tube but there is some oil in the intake. Smoking only shows in high vacuum situations.

I’m lost as to where to go with this diagnosis. Anyone have an inkling?

 

[MrQ]

Just a thought, try disconnecting the tube from the filler neck to the intake and block off both ports. Try your acceleration test again.

 

[MrQ]

So @96AWD5.LOL is my brother. I just talked to him and he says that he is having vacuum in the oil filler neck. This is definitely an leaking intake issue. I'm of the opinion it could be a warped or damaged lower intake or something wrong with the intake surfaces on the new heads.

 

[96AWD5.LOL]

Vacuum is not egregious, and only present when PCV is connected as expected. When at higher RPM's vacuum at the oil fill disappears and there is nominal air pulsing out.

I did see there is a exhaust leak at the Y-pipe connection on the passenger side. Smoke emanates from there when popping the throttle after idling. higher rev's show no sign of smoke from that connection.

I'll be performing a leak down test and a general vacuum test today and will post the results.

 

[974X4BLACKSPORT]

If your transmission uses a vacuum modulator, check for transmission fluid in the vacuum hose from the the modulator to the intake "t" or manifold port. I have seen this happen before, but each case is different.

 

[96AWD5.LOL]

If your transmission uses a vacuum modulator, check for transmission fluid in the vacuum hose from the the modulator to the intake "t" or manifold port. I have seen this happen before, but each case is different.

Thanks for the suggestion. The transmission has been rebuilt and the modulator is new. I did inspect it and there is no trans fluid in that vac line. This issue is showing on the dipstick, oil is low. As a matter of fact, from less than 250 miles from last oil change I was down to just above the hatch marks.

 

[974X4BLACKSPORT]

Oil can only enter the combustion chamber in one of three ways, and they are:
1) through the intake manifold
2) valve stem oil seals
3) piston rings
Once you eliminate two of the possible causes for the oil consumption, you will then be left with the culprit.
If your sure no oil is getting pulled into the intake manifold, or have eliminated all sources, move to the next cause.
Physical inspection of the valve stem oil seals will be necessary, but you have to do them all because one seal could be leaking a lot, or all of them could be leaking a little to cause the problem. Remove the valve covers and do a visual first to see if there are seals still in place, but then the spring will have to be removed, and each seal will have to be visually and physically inspected, while your at it you might as well just install new ones to eliminate the source off your list of causes.

 

[96AWD5.LOL]

This was resolved. I decided to replace the valve seals and as it turns out all exhaust seals on the passenger side were lifted up off the seat. #3 was at the top of the stem. Replaced with fel pro valve seals and all seems to be resolved.

For reference, these were King’s cylinder heads 90-93tm casting with less than 2000 miles on them. The seals King’s uses seemed to have a larger ID than factory or the felpro seals I put in. They also did not have a metal base.

 

[massacre]

Do you have a part # for the fuel pro valve seals?
Thanks!

 

[96AWD5.LOL]

Do you have a part # for the fuel pro valve seals?
Thanks!

SS72686

 

[massacre]

Awesome thanks!