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I have a 97 f250 with the 5.8l. This weekend I removed the throttle body in order to replace a throttle position sensor that I believe has been the source of my power loss and to do some cleaning. Upon inspection, I found that there is oil pooling up in the backside (cab side) of my upper intake. The pcv was only about 8 months old but, I went ahead and replaced it anyways. I show no other signs of blow by. Compression is excellent, no oil in the air filter, no oil burning signs and no fowled or oily plugs. I've never had the valve covers off so I couldn't tell you if there are baffles under the vent ports.
Is this a common occurrence with these motors? I've been thinking of installing a inline oil separator after the pcv to collect as much oil as possible but, if there's a issue that I'm missing I'd rather fix it than try to cover it up. Any suggestions are appreciated.
where is your pcv entering the upper intake? if its running into the back port you will have this issue. there was a TSB on moving that to a central location on the upper intake.
where is your pcv entering the upper intake? if its running into the back port you will have this issue. there was a TSB on moving that to a central location on the upper intake.
My pcv line enters the intake in the center, not into the back of the Intake.
so you have a bad pcv then. are you buying a motorcraft pcv? or you have blowby the rings
I just replaced the pcv when I found the oil in the intake. I'm not sure which brand I bought. I'll have to check when I get home tonight. Is there a specific reason why the Motorcraft is better vs others? I have no other signs of blowby. My compression is phenomenal so I highly doubt my rings are worn enough to cause that. I only have 85k miles on the truck and everything else checks out ok.
Use on a Motorcraft PCV valve. Cheaper ones weren't designed for these engines, but strictly for mass production.
Also, your gonna have some oil in the plenum due to the setup of the PCV system. It draws crankcase vapors into the plenum. As air temp changes, the vapor leaves behind oily residue, same that you see if you have ever driven your vehicle a few miles in cold weather and the engine never reaches operating temp. That milky froth is moisture/crankcase vapor sticking to anything cooler parts and clings like glue when cold.
Manifold vacuum and the #8 runner pull the remaining part of the vapor to the rear and that is why it pools heavily there. That's also why Ford moved the PCV emission hose from the rear of the plenum to the center since all the trash being sucked into the #8 runner and into the cylinders was causing detonation and grenading the #8 piston.
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