All I have found on the forum is that the crank bolt size on a 190 or something is 27mm. Is it the same for a OM617? I need to know quick so I can go buy one before they close. Sears or auto parts store?

27mm on a 617. (Head size, not bolt size.) The bolt is a M18 x 1.5 x 45. But you definitely won't find one at Sears or most parts stores.

Or are you looking for a socket?

thanks! ya head size.... damn pulley is is either loose or needs a new damper/balancer or whatever they are called on the om617.

will the "starter bump" method work to get the bolt loose? Works like a charm on the SHO
Thanks

Save yourself some trouble and check the pulley first. The pulley is bolted to the balancer by six socket head cap screws. (Maybe 5, depending on which model 617.) The damper is sanwiched between the pulley and balancer. (Maybe 5, depending on which model 617.)

Unless the entire assembly is loose, the is no need to loosen the crankshaft bolt.

ummmm.... ok thats sounds good to me. I cant seem to get to the front of the pulley because of that darn fan in the way. I also can not seem to figure out what size "bolt heads" are attaching that fan/clutch to the water pump. I basicallt need to remove the fan to get a clear shot at the crank.

you mention screws(?) holding the pulley/dampner/balancer ass'y together? Is this right. So I should look at those first you say? I would say that the part of the the cranl pulley that has the timing marks on it seems solid but the pulley wobbles very bad. I thought it was a bad water pump and was trying to remobe the belt to get to it... then I noticed the pulley moving!

Than belts seem to be a PITA to even deal with.

Thanks again

All the more reason to check the pulley screws. This could be your lucky day. You would much rather have a loose pulley than a loose balancer.

The fan clutch bolts have 10mm heads. You might need to grind a box-end wrench down a bit on the outside in order for it to fit. Using an open-end wrench runs the risk of rounding off the bolt heads.