Quote:
Originally Posted by mprhoodlum
My 96 4.0 developed a lead on the back side of the pass. head. I thought it might have been either a freeze plug or a head gasket leaking. Turns out it was the intake gasket. When I pulled the intake I found a tremendous amount of what looks like burned oil in the intake ports. I have had problems in the past with the number 6 plug gas fouling. I've replaced the plugs twice but didn't find excessive oil at all. Could this be an intake gasket leak from the oil gallery to the intake where oil is being sucked up into the ports? The truck doesn't have any noticeable oil consumption, but I do change the oil every 3000 miles. The EGR tube into the intake also showed a lot of burned oil.
Thanks for any suggestions.
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First off, I'd say if its not a complete fail, your PCV is beyond needing to be changed foremost.
2nd I'd watch a few videos on sea foaming your engine and clean up what you cant get at with a small gasket scraper and get that out of those intake plenums IF NOT yank the whole intake plenum upper and lower and manually do it properly by soaking in a bit of gasoline or kerosene and taking both a small wire brush and a stiff bristle tooth brush and clean that all out.
Also, the condition of that oil is atrocious and your truck deserves better of you. Change your oil more often (5000-7500miles depending on use and by use I mean harder or offroad use the lower more frequent miles) and I'd switch to a synthetic - Mobile 1, if ya wanted or needed a suggestion in the OEM weight. and dont fill past the 5 qts, and when you check it, make sure its after an hr or two of driving it so all the oil is in the pan before taking a measurement off the dipstick because you may be adding oil when you dont need it. Too much oil creates too much crank case pressure. If you ever find the dipstick pushed out of its hole, even slightly thats a bit of proof. That may be why you had a gasket failure.. Bad PVC and too much pressure in the crank case.
I would almost bet that the intake tube from the large 1" hose coming off the pass side valve cover is also gooped up. Consider investing in a couple cans of brake cleaner and some disposable rags to clean those out with.
Now for the bad parts. It doesn’t take an aeronautical physicist to know that the majority of any blow-by issues can be traced to leakage past the rings. But there are several different paths. Yes, a weak connection between the ring face and the cylinder wall is a common source, but don’t ignore the possibility that the pressure is squirting past the back side of either the top or second ring due to worn ring groove clearances. Rings are designed to fit with very specific clearances to allow the rings to function properly. Twist is built into both the top and second rings to allow them to function at their highest efficiency. If the ring lands are worn or not completely flat, this will reduce sealing efficiency. The only proper repair for this issue is a new set of pistons.
How many miles are on this truck and how many of them are HARD miles?
You could have a bad oil pump, bad rings, or combination thereof.