I.H. W4 Motor Question

I bought a W4 from a widow last summer that had not been run since the 1970's. It was parked due to a knock in the motor and left along a field edge. Long story short: I tore into it this winter and discovered the cylinder closest to the radiator spun a bearing and ruined the crankshaft. Wasn't fixable. I bought a ground crank, got a replacement rod, have new bearings, and am putting in new rings. Here's my concern: Since I don't know what caused it to spin that bearing, do you think I should replace the oil pump to be on the safe side?
Thanks for the advice.

If you are going this far then a new oil pump looks like the thing to do. If you have any doubt at all, replace it even if it goes a little beyond the budget. Let us know how it runs when you're done. Jim

Finding a new pump might be both pricy and long term. The easier answer is to check the original pump as follows.
The gear to housing clearance should be less than .001" A bit over that with no scoring is OK.
The cover should have a clearance of .0005" to a max of .001". The cover is cleranced to the gear depth with thin gaskets (very thin!) used as shims as well as gaskets.
The cover probably needs to be flattened on a piece of 200 then 320 then 400 grit silicon carbide on a flat glass surface. Use rotation and multi direction strokes to assure flatness.
The shaft bushings should be also less than .001 difference from the shaft. the new crank should take care of oiling, but to be sure, use a squirt oil can in the oil pressure line threaded hole to put oil into the gallery. It will begin to cone out of holes where the gallery takes it. With the crank out, the oil will really pour out. after it is in, the crank main caps and rod caps will hold (with assembly lube on the bearings I hope) the oil in and the squirt can pressure should be harder to do and oil will come out of the cam bearings. If you are nervous about the upper end, the engine must be rolled over such that the hole in the cam bearing lines up with the block port to allow the oil to go up. Good luck, I hope this helps. JimN

you could take the pump apart and inspect it. best to just put in a rebuilt or new one.its the heart of the motor.what caused the failure?....worn brgs,too much clearance,inadequit oil supply or no oil to brgs. also too tight clearances will cause that but that will happen after an overhaul.this most likely happened due to wear and possibly neglect over the years.be sure to clean the oil galleries good also.dont want that old grit going around through your o/h.

That's what I got to thinking. Thanks for your opinion.

Thanks for describing the process on how to check it over. I have a mechanic friend, and I'm printing your advice to have him consider helping me with your idea.

Will do Jim. I'd like to have it running by spring, then see if I can get it painted this summer. She is total rust right now, but the sheet metal is straighter than straight and the rest of the tractor was very tight. Couldn't let the old girl go to the crusher.