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bad camshaft may be the culprit to all my troubles

I had my 89 XJ listed for sale and one person that stopped to see it decided to not buy it but, since he had retired as a mechanic for Phil Long Ford in Colorado Springs, CO, he suggested I pull the cam out and check it.

He said that over the last few years he had worked there had been several Jeep 4.0 engines came in with bad cams.

The cause?

The EPA's ban on engine oil with zinc additives.

Zinc works as an extreme high pressure lubricant for flat tappet style valve lifters (non-roller lifters) and prevents premature wear on the cam and lifter faces.

A new cam is on order thru Auto Zone but I'm going to start using a zinc additive or a so-called "high mileage" oil with Zinc from now on out.

Budd

Reply to
Budd Cochran
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Ok, that's odd to me. Only issue I ever had with a cam was stalling (no acceleration except at speed) from my 82 C-10 chevy POS. That was due to a worn down pump lobe. The wear was due to a "well known" oil starvation issue on that part of the cam.

Reply to
DougW

For a while, many manufacturers, especially the Chevy division's 305 C.I. engine, had poorly hardened cams which resulted in performance issues like mine and, thanks to my wonderful memory that I think I used to have, I spaced out the symptoms.

I got the cam out with a home-made handle to help with guiding it and found galling on the lift ramps, an average 0.030" wear on the lobe tips and 0.015" on the base circles.

All lifters had cupping on the faces and one was collapsed and the one next to it was plugged with engine crud which reduced it's ability to pump up and lube the rocker as well (the AMC design pumps oil up the pushrods to the rockers).

I thought the fuel pump had gone out or the filter had plugged and replaced both but the stalling and cutting out continued.

Got almost all my parts and while it's down I'm converting to an open cooling system, replacing the motor mounts, replacing a damaged passenger front fender, and putting in a better engine-to-chassis ground.

Budd

Reply to
Budd Cochran

I have to admit when the pump lobe went out on my C-10 it was not the first thing I thought it was.

The wear doesn't seem that bad, but the fubar lifter that's another thing. Same with lots of vehpickles, lube goes up the lifter.

Fingers crossed that you got the culprit.

Reply to
DougW

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