The shop I work for was tasked with a rebuild on a D3 Cat with an S6S Mitsubishi engine. When we got down to the crankshaft and started disassembly one of the main caps is broken/split right down the center. I'm trying to locate a blank bearing cap to replace it and have had no luck with that. I was hoping that someone in this site may be able to help. I have not posted much in the past, mostly just read and watched. If anyone can point me in the right direction that would be great. Thank you.
Yikes what caused the cap to crack?? I'd be checking that block over good, I'm sure the crank loved the lack of support as well... Damper issues?? Might be better to start off with a good block/crank? You would most likely have to find a used block to rob a cap from anyway, plus all the machining involved.
Yeah, I'm not sure as to the cause. It had started wear pretty bad on the rear journal of the shaft as well. We have found a long block for around $13,000, but that's honestly more than they paid for the whole machine. What we really had in mind was to find a blank cap and send the block off and have it line bored accordingly. Not sure that it will work out the way we want. I told the higher ups that I would take a chance and just find a cap for that motor from a downed machine and see if it will work. He says that it needs to be seated like the rest, but I'm not sure. What do all of you think?
Using a used main cap generally requires fitting to the block. Using a press to spread the used cap, then milling off or grinding off material @ parting line and fitting @ sides before line boring.
I see. I've honestly never been in this situation, so it's new to me. Do they make blank caps for that situation?
I'd be contacting a reputable local engine machine shop, they should be able to source a cap. I believe the s4s uses the same mains, possibly same caps? Take the block and crank so they can check it for cracks and check the crank for straight, plus do the machining if everything checks out.
Good Advice I've no idea if blank caps are available for Mitsu--. Cylinder Block Crankshaft BORE center-line location is critical, establishes deck height (distance to cyl head mounting surface) and gear train clearances (camshaft drive gear, oil pump, balancers, injection pump etc). Various repair procedures; plasma arc build up, spray welding, electroless nickel plating, tig welding, brazing and sleeving the upper crankshaft bearing bore. On large diesels, main bearing failures (crankshaft color blue-ish) typically cause the main bearing cap to shrink (pull inwards), caused by extreme overheating. The small-ish machines with throw away engines often are not worth the repair cost!