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Originally Posted by Hank
Those oil pumps go for ever. It's not a bad idea, but I would not sweat it.
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X2. The driver and driven gears will last longer than the rest of the truck. The pump body is part of the front cover, and doesn't need to be replaced. What you might consider is just facing the cover plate. You'll need an 8mm box wrench (12 Point) to get the bolts out. The plate surface will likely be scored lightly, but can be lapped with a few sheets of 400 emory paper on a surface plate or other FLAT surface. Just lay the emory on the flat surface and move the plate back and forth till you have lapped all the scoring out of it. A granite kitchen counter makes a good surface plate, just don't get caught. Don't use a piece of wood, not flat or hard enough to do a good job. If you have access to a cast iron surface plate, use valve lapping compound, directly on the surface plate, and skip the emory. Replace the thin paper gasket. There is a feeler guage spec for the gap between the gear faces and the pump body face, using a straight edge, but as long as the bottom plate is lapped clean, you won't do much better. About the only other parts of the pump I'd bother to consider replacing is the relief valve spring and plunger, but not a big deal. There are mixed opinions on packing the pump with vaseline when you put it back together. It does help to pull a prime when starting off with a fresh pump, but frankly I still believe in drill driving the pump for as long as it takes to pull the prime, and I skip the vaseline.
If you are going to replace the cam, refit the new one with some assembly oil, or STP, and be VERY carefull when putting the cam in as cam bearings are very soft and easily scored. Make sure everything is spotlessly clean.
Always replace lifters when replacing a cam. If you're going with a performance cam with extra lift, be sure the lift doesn't exceed the spring compression dimention, and also consider roller rockers.
