Crankshaft woodruff key fitment? OM603 - PeachParts Mercedes-Benz Forum

87tdwagen · #1 02-23-2020, 09:35 PM

Dear all,
What started out as a fairly routine crankshaft seal replacement on the 87 TD OM603, has turned into a bit of a frustration. After pulling the crank damper and hub, I quickly realized the source of the leak was a worn groove in the hub, having no idea if original or not it needed replacement.

Installed new crankshaft seal and new MB hub. The hub started on the woodruff key about half way in pushing by hand until met resistance, and then used the hub bolt to seat all the way. After reassembly of the damper and crank pulley, I noticed some damper wobble at idle,

.

Disassembled again, pulled the hub. Noticed the woodruff channel in the new hub, bent outward, radially, as if the woodruff key ramped the opening of the channel as the hub was being forced on. Well, I guess this is my wobble. The woodruff channel in the hub is not widened nor is it in the crank, the rearmost section of the key, the tip facing the engine, snapped off about 1-2mm, have no idea where it is, likely in the bottom of the oil pan. Hopefully it'll come out in an oil drain. Not sure if it will do any damage. Ideas?

Anywho, the woodruff key that I took out, well 5/6th of it, looks otherwise undamaged, will replace with new, but in playing with its fitment in now 2 bad hubs, I noticed that it is really tight in the old hub from whence it originally came, I suppose this could be due to some mild deformation that I cant see from my last screw up, but approaching it from the backside of the hubs there was a different level of tightness between the 2 hubs, both MB parts.

How tight should the woodruff key fit the hub? Is it normal to expect some minor sanding, fitment of the key to the hub channel to account for mfg tolerances? Is there some trick to ensuring correct fitment of the key to the crank and the hub that I'm missing? I'd hate to have to bugger another hub on what should otherwise be a straight forward maintenance job.

Thanks

PS guardian angels must drive diesels, my damage could have been far worse, luckily it was caught quick.

dieselbenz1 · #2 02-23-2020, 09:49 PM

When I had done this task a year ago a groove was warn on the crank so I fitted a repair sleeve. The key I noticed did not want to stay put in its slot and would push out the back. The key actually fell into the sump which I could retrieve by removing the side oil sump. I used a punch to stamp both sides of the key so I could tap it into the crank channel. That was enough to keep everything in line while tapping on the hub. A loose key will present issues. I never encountered excessive force to reinsert the hub once the key held firmly.

87tdwagen · #3 02-23-2020, 10:35 PM

Thanks dieselbenz1.

Did you get a crank repair sleeve or a hub repair sleeve for the seal?

I've also noticed 2 different types of woodruff key styles for my car, one tha has a beveled end that goes into the crank groove and the second is a squared half moon. Is there a general opinion on one style vs the other?

Lastly, the hub bolt torque I show in Haynes is 148 ft-lbs for the flat washer hub bolt, mine is three heavy thick washers, so that is what I used. Was that wrong?

TIA

dieselbenz1 · #4 02-23-2020, 11:11 PM

I installed the crank repair sleeve I think it was called speedy sleeve but I'm away from home so can't look up the part number. As far as I know the half moon style sits into the crank leaving a flat raised section the keyway on the hub inserts. I recall only one thick washer and I can't recall the torque but my first thoughts that 148 maybe not enough. I'll see if the FM's has it listed.

dieselbenz1 · #5 02-23-2020, 11:26 PM

320 NM I'll send you the FSM pages

dieselbenz1 · #6 02-24-2020, 12:01 AM

Check your bolt if stamped 8.8 or 10.9 that will clarify the torque requirements as stated in FSM. Good luck.

87tdwagen · #7 02-24-2020, 12:12 AM

Thanks, I've got to check which center bolt I have. Regarding the speed sleeve, was that something commonly available?

dieselbenz1 · #8 02-24-2020, 12:38 AM

Just google speedi sleeve you should find several different manufacturers with catalogs listing the sizes.

87tdwagen · #9 02-24-2020, 01:15 PM

Thanks for the tips, found the speed seal from National Seal (Federal Mogul) Part# 99177 for the OM603.

In looking over the old hub, I also noticed some slight buggering of the hub to crank mount inner surface, 180 deg opposite of the woodruff key slot, so I assume this hub had been changed out before my ownership at least 150k miles ago and the last mechanic also had to force the hub onto the crank, causing this.

I used some emory cloth on the crank stub to polish the slight burrs smooth to keep the hub from binding in this area as it is fitted on.

In reading various posts from people the hub to crankshaft fitment seems all over the place, with many folks saying it slid onto the crank easily, to needing to slightly tap it on, all the way to needing to crank down on the crank bolt to get it to seat properly. So which is it?

Most hubs that I have done in the past (non-MB) fall into the easily slips on to needs some slight tapping, a tight fit, but no need to force it on. Is the OM603 any different?

PS, my hub bolt is marked 10.8 so I need to get a new torque wrench to get it up to the 320NM tightening spec.

dieselbenz1 · #10 02-25-2020, 12:34 AM

Glad it's working out for you. I've always had to just gently tap it on but I've never before found a key that was so loose in its keyway. Make sure it can't move before putting the hub on, that's why you likely had issues with your first install and read others had to force on the hub not knowing they sheared the key?

87tdwagen · #11 02-27-2020, 07:52 PM

Well, after a few days waiting on a new hub, I was able to finally put this to rest. It took a lot of patience and care to polish some light galling on the crank stub with emery cloth to where the new hub would engage smoothly pn the crank and up against the crank sprocket at the end of its travel.

I also used a new woodruff key to replace the damaged one and it fit the crank channel perfectly. It seated completely but still allowed for a slight rocking motion in the crank groove to allow for some minor range of adjustment along the curve as the hub channel engaged it if it was not perfectly level.

Of course as luck would have it on what was supposed to be the final mounting after the crank seal was installed, the key knocked out, clunk, bottom of the oil pan :mad Oh well, due for an oil change anyway.

One of my most valuable tools, an aluminum pencil magnet, inserted through the drain hole and wallah, the new key and the sheered end of the old key.

Reengaged the key level and seated the hub smoothly. I found that warming up the hub to about 130 degrees helped tremendously in slipping it on vs cold which would require tapping on. Also advisable to mount the hub alone separate from the balancer and pulley as those can be attached later and not having all that weight will allow you to engage the hub squarely and smoothly onto the crank. The balancer can only be fitted one way and the pulley itself is balanced so does not matter, but the backside will tell you how to mate it if you want to be exact.

Surprisingly, torquing the hub bolt was not too bad with a rental torque wrench that would get up to the 320NM. With the hub backfaces full seated against the crank sprocket, once you snug the bolt, torquing should be quick.

Note, if you have the multiple washer setup as I did, make sure you coat all mating surfaces with oil between the washers, since you should also coat the threads, you best bet is to fully immerse the washers and bolt combo in some motor oil prior to installing.

Many thanks to dieselbenz1 for the tips and assistance, Hopefully my notes will be of use to others.