Wd 45 Diesel ?

The  oil pump is driven off the cam, if that's what you are asking.  If you are asking about worn bearings, mostly cam, but if the crank bearings are loose, that will also allow the pressure to drop.

Well here is the deal.  These engines typically are a money pit, the deeper you go, the more it costs.  This is not always the case, but often, just ask anyone on here who has overhauled on of these gals.  Your idea is worth a try, I think I would start by plastigauging them before all the work to take them apart.  If they are in spec you have other problems somewhere.  I speculate that if they are loose, then so are the cam bearings, and the oil pump is week as well, because of all the material floating around the engine, or the hours on her, affect pretty much all parts the same.  I think dropping the pan is a good option, just to have a look around.  The other thing I would do before a tear down, is double check what you are seeing with a quality pressure gauge.  A $100.00 test gauge set now, could save you spending thousands, or it just might confirm what you are seeing, but seems like a small price to pay to know for sure.

Had the same problem with a D262 engine also, same thing. After a years years of on off again working on it, and taking it to someone else, this is what we found.

Edited by Don(MI) - 18 Jul 2012 at 8:15am

Cam bearings have absolutely no effects on oil pressure on the Buda 230 and the 262 later produced after the A-C acquisition. The cam bearings are not pressure lubed and depend solely on the oil draining off the rockers from the head for lubrication. Your only options for low oil pressure are worn main or rod bearings, worn oil pump, weak/broken oil pressure bypass spring. Since this engine has the bypass style oil filters, it may not run a great deal of oil pressure. Best bet would be look in the service manual and see what it's supposed to be. I don't see why you couldn't slip new bearings in it from below if needed. Probably the hardest part of the job would be oil pan R&R.

Thanks guys. Yes I did go to a good shop and borrowed a quality guage to check the oil pressure so I knew where I stood. I also have the service manual and I know they can be a money pit. But this old girl is pretty sweet and will be light duty only.