rmr25

In pursuit of a leaking rear main seal, I've assiduously followed Bill Ball's magnificent "how-to" posted some years ago. Everything went as he described. Until today. Then an abrupt halt! The cheesehead bolts will NOT budge. With the cut-off 12-point tool locked into position by the TT shaft coupler, I've put at least 100 ft/lbs on with a breaker bar. Nothing! I tried BB Blaster and heat. Nothing! I then tried knocking the bolt head counterclockwise at the 3 o'clock position with a chisel and 8-pound sledge hammer. Still, nothing.

Bill Ball's comment on this was that he'd never encountered anything like it in 6-7 flywheel removals.

At his point the only way forward I see is just to chisel the heads off with an air hammer. But before I do that, Bill suggested I check opinions here.

I have the PO's records. Nothing in there about flywheel removal, although they do show TT bearing replacements around 55,000 miles. My car now has 73,000.

Garth S

Bob,
Have you got enough room to smack the bolt heads (axially): i hate to beat on the crank .... but a crisp blow on the bolt heads is often the way to break the binding corrosive film.
Also, an air impact tool will be far more effective than a long breaker bar on 8 - 10mm bolts, for it is too easy to shear them off, or destroy the heads with a steady torque from a bar.

If you have already tried these steps, I will suffer with you in silence ...

AO

PB Blaster doesn't work. Order some KROIL, actually Aerokroil is what you want...

http://www.kanolabs.com/

Lizard928

I would give them a couple good swift hits to the head with a hammer, driving them in towards the crank.

And if you have the option, get an air driven impact gun with the right tool on there. That has worked for me everytime.

Mrmerlin

I guess that you have the flex plate out, keep it matched to the flywheel. Is it possible to get a air gun the kind you might use for wheel removal?
This may entail that you remove the bell housing. I wouldnt be beating too much on the sides of the bolts and not too much front to back as you will be transferring all of the force to the #4 web where the thrust bearing is, try heating the bolts then spray with aerokroil orange can, a few times then let things sit for a day and try again my guess is the bolts were loctited so a few heats and soakings should begin to loosen things up

JP Rodkey

Well, I had to use a chisel on a couple of boogered flywheel bolts once. I used a standard cold chisel with a large hammer and worked pretty well, as I recall. An air chisel would be better if youi're looking to shear off the head, but just a few degrees of rotation with a chisel by hand will allow you to remove it the rest of the way with ease.

rmr25

Thanks, Guys, for the suggestions. I've only got a small space to work with; the TT and shaft are moved about 11/2' inches to the rear, per Bill Ball's earlier write-up. Hence, I can't really get a head-on hammer blow to the heads, only an oblique one with the cold chisel I mentioned above. And that didn't crack it. I'll try the heat and Kroil treatment before I go to the extreme of chiseling the heads off.

Bill Ball

Yep, Bob has limited space for big tools because he's trying my "shortcut".
http://www.billsworkshop.com/P928S4/seal/seal.htm
The bolts aren't buggered (yet); they are just far tighter than Ive seen. He's had a breaker bar on them and is using a virgin triple square. He's used heat.

They're supposed to be 60 ft lbs and I haven't seen them much more than that. He may have to drill the bolt heads - that'll be fun even with a rt-angle drill - or give up on the shortcut (I never do that). I've had success with other Allens drilling MOST of the head to weaken the bolt, then turning it with a chisel and harmmer. Intact, it will be hard to turn with a chisel.

What else?

jon928se

While trying to turn it with the triple square coat the triple square with valve grinding paste - reduces the chance of slippage.

Mrmerlin

well there is alway the good old pull the engine chances are that if the rear main is leaking it might ba great idea to refresh all of the other external seals and you will reduce the effects of hitting the crank my guess is the bolts were impact tightened, and the only way to get them off will be the same way, just another way to fix this

rmr25

OK, Guys:

The bolts are out!!!

After more hours and swearing than I can recount, I removed them by devising a variation on Bill's procedure. Remember, at the point of removing the bolts, Bill suggested using a 1/2" open end box over a cut down 12-pt triple square bit. My problem was that the bolts were torqued so tight I couldn't get a proper angle on the wrench to apply the needed torque. The wrench kept slipping out of the bolt head grooves. I'm not exaggerating: THOSE BOLTS WERE IN THERE AT LEAST 100 ft/lbs! And no Loctite either.

Here's what worked. With a dremel cutting disc I reduced the length of the 12-pt bit to 26 mm. The shank end, where a 6-pt 1/2" socket (3/8" drive) would fit, is about 10 mm. At the other end, where the 12 pts are, I also left about 10 mm. These bit dimensions meant that with a socket and ratchet in place, the overall length was 59 mm. This was enough to slip the tool/ratchet in place in front of the coupler. Then, as with Bill's procedure, I just snugged the coupler against the head of the ratchet. I cycled three times heating the bolt head and immediately cooling it with water from a spray bottle. Once done, with a pipe over the ratchet handle for more power, the bolt relented and I could smile again at our beloved 928 engineers.

I hope no one ever encouters a mess like this when doing a rear seal replacement. But even short of that, I think making a socket tool from the standard 12-pt, triple square is the way to go.

I want to express my sincere thanks to all of you who offered suggestions. But most especially, to Bill Ball. Without his patient encouragement I never could have done this. He's one of this Forum's True Treasures!

Bob

Bill Ball

Excellent idea for a new tool. I think the 12-pt I used had a shaft that would fit in a 13mm socket.

Hope the rest goes smoothly - it should.