Weird camshaft wear pattern

[Michael A. K. G]

Hi guys,

I pulled my 250 out to give it a thorough inspection and seal up the myriad of oil leaks (you name it, it leaks). When I removed the oil pan to do the rear main, I noticed some odd wear on the camshaft. The lobes all have shiny spots at the tip, as one would expect for a 30 year old truck. Some of the BACK sides of the lobes have irregular shiny strips on them. Some are straight and centered, some are off center, and some are wavy!

Does this mean some of my lifters are shot? How much of the valvetrain to I get to replace? All the lifters? Camshaft? Cam bearings? Pushrods? Rockers? Do the lifter bores need to be reamed?

Is it possible to rent (or buy really cheap) cam bearing pullers? I really doubt I want to yank these with a slide hammer. Since my truck is now obviously out of commission, hauling a mostly assembled long block to the machine shop is rather difficult. I may have to disassemble the whole thing.

Also, the timing gear marks line up at TDC on the EXHAUST stroke. I always thought it was supposed to be on compression. Is that normal, or does that mean the idiot previous owner put the cam gear on backwards?

Leakdown is at 10% for three cylinders, all leaking through the crankcase. Is it rebuild time? The rear crank bearing looked ok, though there was a small groove under the rear main seal.

I'll measure the cam lobe lift this afternoon with the overhaul manual trick (dial indicator on the pushrods, with all the rockers removed).

[JD72]

Anytime you change cams you need to get a new set of lifters, also getting new rockers is a good idea. It would be much easier to go ahead now and get the new parts and go ahead and get head work such as seals ,springs and guides while you got it apart the first time if money permits. No sense in half way doing it then having to go back and fix something else. It should last for quite a while after you get eveything reworked .