401 diesel questions

I have finally been able to start disassembling the engine in my 400 diesel and have a few questions. I found as I expected that the engine was pretty well worn out. Much to my surprise the engine has 4-1/8" bore M&W pistons. What I'm wondering is what is the part numbers for the rods and the crank for the 251 cu. in and 267 cu. in. engines and are they interchangeable? I don't think the rods are original because the caps are split at an angle to the rod instead of perpendicular to the rod. I'm concerned that the rods may also be M&W and I may not be able to get replacement bearings since M&W is no longer in business. Would I be better off to get refurbished case rods? I am planning on replacing the sleeves and pistons since the ones I have are shot.

I am planning on having the heads, block, radiator, and water manifold cleaned and pressure tested since engine oil is being pumped into the antifreeze and I haven't found any bad gaskets that are leaking. I am also wondering is there is anything else to watch out for when tearing down and reassembling this engine? Are there any parts that aren't available anymore that I need to save?

M&W didn't make rods. Most larger CASE rods are angle cut. The 251 block is 6400AA for a casting number. The only physical difference between a 251 and a 267 is the bigger pistons and bigger cam bearings for the 267 plus the top sleeve hole it larger. I totally gutted my A251D and rebuilt it from scratch a year ago. Cost a little $$$ but wasn't too bad. Anybody can thrown in a 267 but then it's not original anymore. Now, the only way to do the pistons and sleeves is to either buy new sleeves for your old pistons or get a hold of John Saeli or Don L for a stock set of 4" replacement sleeves and pistons unless someone has bored the top sleeve deck larger for the A267 sleeves. You cannot use the commonly found 4 1/8" aftermarket sets as they are for gas engines only. Cam shaft bearings are around $350 but a few guys on here have found cheaper alternatives. As for the heads, when I had mine done the only place to get valves was from CASE at $50 EACH, so mach sure you take it to a competent machine shop so you only replace whats bad. You also should pull and clean the power cells out and service them as outlined in the service manual. I had one that was cracked. There are a couple O-rings that get installed with the head gasket to seal off the oil from the water and one of these may be bad. One other thing to check is the coolant is in the oil filter base, and if the gasket there is bad it may be the culprit. The first time I messed with one I thought the pet cock was a filter base drain and opened it only to have anti-freeze pour out not knowing that this was a primitive oil cooler and also a spot for the LP gas regulator to hook to on the LP tractors. I bought my gaskets kit from CNH and it even came with hoses. John Saeli provided the cam bearings, valve train parts, Don L supplied my sleeves as my pistons were good, and my bearings and rings came from www.agkits.com, and Spencer Diesel in Spencer IA rebuilt my injection system. All in all it's a pretty powerful tractor being it's stock 55hp.

I had a set of 4 1/8 pistons that had the bottom side of the top compression ring wore out. The machine shop was able to buy spacers for the top ring groove and machine the piston groove true again. I think he said hastings was the only one still making spacers. If M&W made the over bore kit, did they just bore the sleeve bigger? I know it would make the sleeve 1/16 thinner on each side. Even with higher compression, would the gas sleeve work? Wasn"t this a common practice when the overbore kits were being made by aftermarket companies back then? I had also heard that everything below the cylinder head was the same on gas or diesel, as far as internal part for 400's. I"m just curious.

Here's the bottom line. If your block has been re-bored to a flange dia. of 4.997, a modern 4 1/8" or 4 1/4" kit will work. However, if you have an original block with a flange dia. of 4.873, we can still get a 4" sleeve for it, but no 4" pistons anymore. We have partnered with a local machine shop to bore the new 4" sleeve out to 4 1/8" and then we furnish a reasonable priced 4 1/8" piston. Now, you can have a 267 cu in. without re-tooling the block. "We take care of everything"