Budd Cochran wrote:
> 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.

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.

--
DougW