TheSamba.com :: View topic - Trouble removing the fan hub on type 4 engine

Sat Apr 10, 2010 3:18 pm

My bus has a bad oil leak and I am pretty sure it's the rear oil seal. The trouble is, I can't get the fan hub off to replace the seal. The picture shows the problem - the metal strip/plates under the bolts are 2mm steel (the left-hand one is actually 2mm stainless steel plate) but they are simply bending as the fan bolts are tightened. I've tried shock (hitting the hub with a hammer) and heat (blowtorch on the hub) but it won't shift.

Since this is the first time I've done this, though, I'm not sure if the hub looks normal. The rear face appears to have been recently ground off flat, and looking at it, I'm starting to wonder whether some cowboy has welded it onto the crankshaft - but I can't think of a single sensible reason why anybody would do that. Any opinions and suggestions about what I can do now would be welcome.

Sat Apr 10, 2010 3:29 pm

Looks welded to the crank to me. I just replaced the fan hub seal in my '79 two weeks ago. I used old VW keys behind the bolts to pop the hub off and had no trouble.

Sat Apr 10, 2010 3:37 pm

VDubTech nailed it, somebody welded your hub on the crank, either live with the leak or take the engine down, find another crank and hub and start all over.

Sat Apr 10, 2010 3:41 pm

I don't know, with a dremel, some time and some careful grinding I bet he could get that hub off the crank, clean up the end of the crank and install a new seal and hub and be ok.....ideally you would wanna tear it down and replace that disaster but if it's an otherwise good running engine I would exhaust all other possibilities before tearing it down.

Sat Apr 10, 2010 4:05 pm

Thanks VDubtech, your photo makes it pretty clear what I have to deal with. I'll try grinding the weld off carefully. It looks like I should be able to grind at least a few mm off the fan hub face and the end of the crankshaft without making either of them unusable. Is there any reason why that wouldn't work? As long as there's still some lip on the hub to center the fan, and the crankshaft face is recessed so the center bolt tightens against the hub, it should be OK ... right?

Jeez I hate cowboy mechanics. Maybe the guy lost the woodruff key and couldn't be bothered to get another one.

Sat Apr 10, 2010 4:09 pm

WTF would someone do that?, I'm with Vdubtech, grind it off, even if you destroy the hub the crank should be salvageable, unless the keyway is hooped and that's why it was welded. Either way there has to be innovative ways to save it without a full teardown.

Sat Apr 10, 2010 4:11 pm

man, that sucks. what a crappy thing to find. you probably can get that off with a dremel and patience.

Sat Apr 10, 2010 4:21 pm

I would do my best to get that hub off without ruining the end of the crank, but I would absolutely replace that hub.

Sat Apr 10, 2010 6:11 pm

I'd go find the PO and get some of my money back. That really sucks. But you can probably dremel it - although you may find the key is toast when you get there and that is why it is welded. I might leave it alone and look for a core engine to rebuild.

Sat Apr 10, 2010 6:17 pm

SGKent wrote: you may find the key is toast when you get there and that is why it is welded

If it turns out that is the case and that's why it was welded, I'd replace the seal and reweld the hub back on....but that's just me.

To the OP:
That seal doesn't appear to be leaking to me....where exactly is your oil leak and why are you looking at the fan hub seal as the culprit? If it was leaking your engine case would look like this-yours looks for too clean to be leaking from that seal.

Sat Apr 10, 2010 9:16 pm

what does heat from welding like that do to the #4 journal and the seal?

Sun Apr 11, 2010 12:14 am

VDubTech - the engine has been washed, that's why it's so clean. Basically the whole rear of the engine had a layer of oil. When the fan came off, the case was covered in oil from the breather box down to the mountings, and pretty much evenly on either side of the hub across the whole rear face of the case. The inside of the fan shroud was completely covered in oil sludge though some of that could have been old. I'm guessing that oil has been leaking through the seal onto the fan, and being blown everywhere from there.

I'm also guessing that the other candidates for leaks (oil cooler seals, dipstick boot) wouldn't have spread so much oil around so evenly?

SGKent - I wonder if the PO (in Australia, sadly, so no chance of money back) melted the seal when welding the hub... I don't want to do the same myself.

Wed Apr 14, 2010 7:19 am

An update on progress - some careful work with the Dremel has produced quite a satisfactory result:

The hub is in perfect condition - the keyway is clean and undamaged. I got a new woodruff key and it fits snugly in the hub keyway. However the keyway in the crankshaft is not so nice (this pic taken looking up from underneath):

What's the opinion on this? I'm inclined to go ahead and reassemble with the new key and tighten it all down well; I can't see how the hub could slip on the crankshaft even if the key does move a little.

Wed Apr 14, 2010 7:40 am

Nice work with the Dremel! That looks salvageable. You might want to get the face of the hub where the washer sits trued up, any machine shop with a lathe can do that, you don't have to get every grind mark out but it should have an even surface. You'll also want to file that nick off the edge of the seal bore on the case.
When you do the final assembly JB weld the key into the slot and give the entire taper a light coat, twist the hub clockwise so the key seats against the good side of the crank groove as you tighten the bolt and leave it to set for a couple hours.
You have little to lose.

Wed Apr 14, 2010 4:27 pm

I think that you can use the dremel to clean up that keyway and get a key in there that will hold.

Wed Apr 14, 2010 6:42 pm

Cut a new keyway 180 deg from that one. Mark your fan timing mark 180 deg from the orig. mark. The biggest problem is cleaning the crank taper to be the same as the fan taper. If there is not enough contact area on the taper you will never get it to stop sheering keys. Also any play between the key and the keyways will result in a sheared key.

Wed Apr 14, 2010 6:48 pm

Wow--damn nice work with the Dremel!

Wed Apr 14, 2010 7:29 pm

Nice work, do what busdaddy recommends then during your next rebuild you can have the crank welded and the keyway recut.

Phil

Wed Apr 14, 2010 8:04 pm

busdaddy wrote: Nice work with the Dremel! That looks salvageable. You might want to get the face of the hub where the washer sits trued up, any machine shop with a lathe can do that, you don't have to get every grind mark out but it should have an even surface. You'll also want to file that nick off the edge of the seal bore on the case.
When you do the final assembly JB weld the key into the slot and give the entire taper a light coat, twist the hub clockwise so the key seats against the good side of the crank groove as you tighten the bolt and leave it to set for a couple hours.
You have little to lose.

BD, Don't you think that JB Weld may be too thick for that tight tapered connection? I would be afraid that JB may prevent a tight fit. I may be wrong. I was thinking Loctite stud and bearing mount.

Wed Apr 14, 2010 8:45 pm

GusC2it wrote: busdaddy wrote: Nice work with the Dremel! That looks salvageable. You might want to get the face of the hub where the washer sits trued up, any machine shop with a lathe can do that, you don't have to get every grind mark out but it should have an even surface. You'll also want to file that nick off the edge of the seal bore on the case.
When you do the final assembly JB weld the key into the slot and give the entire taper a light coat, twist the hub clockwise so the key seats against the good side of the crank groove as you tighten the bolt and leave it to set for a couple hours.
You have little to lose.

BD, Don't you think that JB Weld may be too thick for that tight tapered connection? I would be afraid that JB may prevent a tight fit. I may be wrong. I was thinking Loctite stud and bearing mount.

Perhaps, I've done similar redneck fixes with JB sucessfully in the past (forklifts, tractors), if you get it tight before it starts to harden it all squeezes out of the taper (except the damaged areas). My thinking with the JB was mainly to fill the worn area around the key slot but Phil's suggestion has merit and would be a better long term fix. Either way lapping the taper would be time well spent.

I guess it all boils down to the tools and skills Billfrog has available, he's definitely talented with a Dremel :wink:

Edit: I meant to say Dan's suggestion, although I like Phil's too :wink: