crankshaft hub won't go on "loosely"

[farmboybob]

With little experience in this sort of thing, I bravely was replacing my water pump on a 92 500E with 111,000 miles on it and choose wisely to replace the front crankshaft seal as well, though it didn't leak at all as far as I could tell. Everything seem to come off well, but I didn't have the factory puller for the hub and used a 2 arm puller that fit, whereas the requirement is for a 3 point pulling action as I understand it. But after fitting the new seal with the non-mercedes tool, I think its a miller 9101? I heated the hub to 250F to reinstall it but it wouldn't go onto the crankshaft loose enough to turn so as to align with the woodruff key. I took it off and re-cleaned everything including using 600 grit emory on the leading edges to catch any burrs and was able to tap it on hoping it would loosen up as it went on. But of course no. I tried to turn it by putting two bolts into the hub and levering them with a screw driver to rotate the hub, which I did, but it still was very tight and I could see no way to "feel" when it lined up with the woodruff key properly.

I pulled the hub off again and can now seeing marks on the inside of the hub from tapping it in and also from rotating it. The factory manual doesn't exactly say what to do in that case, probably because if you're a Mercedes mechanic you've lost your job and don't need the information if you've got that far. Any advice on what must be done at this point?

 

[gsxr]

That doesn't sound good. When heated to 50°C the hub should slide on with very little effort / no tools required. If you heated to 120°C and it still wouldn't go on, something is wrong.

You'll need to inspect everything closely on the snout of the crank, and the inside of the hub, to start with. Anything scored or burred will need to be smoothed out. You can mark the crank where the key is located, and mark the hub as well, to get it 95% lined up when installing.

Normally, when heated up, the hub should rotate easily on installation... but marking things so the keyway is pre-aligned still helps. It also helps to have measurements so you know when the hub is fully seated. Photos at the link below may help a little. Unfortunately I don't have any photos with the hub installed, and bolt removed.

http://www.w124performance.com/images/M119/crank_seal/

 

[gerryvz]

Yes, this is odd. The hub does go in a fair bit before it "catches" the Woodruff key.

I just replaced mine back onto the crank the other day, and it went on (tightly) without even having to heat it. It took some back and forth effort by hand to work it on, but it went on just fine and I didn't even have to come close to forcing anything. I was able (per my markings) to get it very close to the Woodruff key, and then rotating it slightly back in forth in the area of the marks allowed it to "catch" the key and go on with no problem. The last few mms I used a plastic hammer to lightly tap it on (see my M119 Top End HOW-TO for more).

Exactly what @gsxr described above.

And all this was after I gouged up the crank snout with a screwdriver trying to get the crank seal out per the factory procedure. I used 1000-grit emery paper to sand down the slight gouges, and this ended up being fine and not affecting the fit of the hub, and polished the crank snout nicely.

This sounds very odd. Perhaps you want to try a light coat of oil after you heat up the hub again. I'd smooth the crank off with 1000 or 2000 grit emery paper, then heat the hub to 100-150F, then lightly oil the inside of it and the crank surface, and install.

You did mark the hub and the engine before you removed the hub, correct?

Replacing the hub & lining up the marks:

 

[farmboybob]

That is all extremely helpful. Thank you both very very much. I'll give it another go following all the advise. The hub was marked beforehand and the key is almost exactly on top of the crank. The hub didn't go on even an 1/4 inch before it got too tight to turn or slide on by hand so I'll check it much more carefullly this time. I also used oil on the first attempt and that didn't help, but on the second after cleaning and "deburring" the edge that did help slightly. I'll use the 1000 and 2000 grit emory.

 

[farmboybob]

Ok its on. Its seems it was getting stuck right at the beginning of insertion. I think the 'snag' was near or at the nose of the crank or the rear edge of the hub or a combination of those 2 areas. I couldn't feel or see any problems with them but working those spots with 1000 grit then 2000 made it so I could get the hub about 1/2 inch onto and off the crank with very gentle prodding by hand though it was tight. and once I heated it, it went on super easily.

Looks like I'm good unless the seal leaks......

Thanks so much again for your help, gentlemen.

 

[gsxr]

Excellent! Good to hear the hub is back on. Hope you have the crank lock tool... need something to brace the crank while torquing to 400Nm. I assume you are using the factory manual and know the Belleville washers need to be oiled, etc?

 

[jhodg5ck]

Alt, you can jamb a wooden wedge on the torque converter/ring gear...give that crank bolt a touch of blue loctitie and a HARD pull on the breaker bar. It'll stay/work/be Fine...:-D

 

[farmboybob]

Yes, I have an 3/4 drive 800 ft lb. torque wrench (more than large enough) and the factory tool for holding the engine from turning. The only thing I didn't have as described in the FSM was the factory hub puller or an equivalent 3 point puller. Since I used a 2 arm puller and the "hang up" was on the snout of the crank and/or the inside edge of the hub, I'm wondering if I mangle things a little by not pulling the hub off dead straight right as the hub was coming off the last bit of the crankshaft.

Its all together now and I'm almost to the point of filling up with fluids and giving it a go.

 

[gerryvz]

A three point puller is cheap -- I got one specifically for the job of pulling my hub, at Advance Auto Parts, and it worked just fine. It's a good tool to have, and definitely better than a two-point puller (which I had and didn't want to use).