crank hard to turn

[ih4by4]

I'm rebuilding a little 155d and just put the crank back in the block with new bearings and seals. I'm worried its a little tight. I had the rod journals turned down and the mains checked. Everything went together ok, but how tight it is too tight. I haven't put rods and pistons in yet. The manual just says that you should be able to turn it by hand. Is there a good way to ease it up some without taking the bearings back to what i just replaced? Any help or thoughts on the problem would be appreciated.

[normde2001]

Did you install the main caps back in their same EXACT orientation? If not you are going to have to use trial and error to get it correct. Use "plastigage" for correct clearance. Otherwise your new bearings are incorrect and you will have to shim one or more caps, but it will never be right.

[1danny]

I'm rebuilding a little 155d and just put the crank back in the block with new bearings and seals. I'm worried its a little tight. I had the rod journals turned down and the mains checked. Everything went together ok, but how tight it is too tight. I haven't put rods and pistons in yet. The manual just says that you should be able to turn it by hand. Is there a good way to ease it up some without taking the bearings back to what i just replaced? Any help or thoughts on the problem would be appreciated.

See if there is a bevel on one side of the bearings, they may be in backwards.

Danny

[ih4by4]

Thanks for the help guys. These mains are solid and there are no caps like i'm use to. But anyways, i found my problem. The gasket i used on the rear main housing was too thin causing a preload on the thrust bearings. I made a slightly thicker one and now she turns freely. Stiff, but a good stiff.

[1danny]

Thanks for the help guys. These mains are solid and there are no caps like i'm use to. But anyways, i found my problem. The gasket i used on the rear main housing was too thin causing a preload on the thrust bearings. I made a slightly thicker one and now she turns freely. Stiff, but a good stiff.

We know there are no caps, I'm talking about the bevel on the bearing. I've seen several installed backward and locked up the engine.

Danny

[normde2001]

OOPS! I was envisioning rod caps, even though he said the rods were not even installed. Just goes to show, you really have to be hands-on to troubleshoot properly.

[alvanko]

We know there are no caps, I'm talking about the bevel on the bearing. I've seen several installed backward and locked up the engine.

Danny

OK. I hope to never have to rebuild my Yanmar, but I'm curious.
How does the crank go in the block with out caps?

[ih4by4]

It has a solid front bearing that presses directly into the front of the block. The back of the block is bored so that you can slide the crank through it. Then the large bore in the back has a piece that holds the back bearing that slides in and fills the large bore and locks the crank in place. I hope that makes some since and i hope that you don't have to rebuild you tractor either. The guy I bought mine from just took very poor care of it. (clogged radiator, cracked block, spun rod bearing, no antifreeze in the radiator, and so on.)

And thanks to everyone for the help. Sorry my stupidity just wasted your time, but thanks for your help anyways though.

[winston1]

I didn't' see any stupidity in any of your posts. Good information came forth here. Thanks for sharing with us.

[alvanko]

ih4by4
Thanks. I think I got it. The front of the crank is smaller then the rear. There are caps in the middle and there must be a larger journal at the rear. Seems odd but I'm used to regular engine design. Almost sounds stronger since there is no cap or bolts at the front or rear.