Crank Nut from Hell

[TxSquash]

I can't get the puppy off! PT Blaster, heat, impact wrench. I've put a breaker bar on it and a pipe extension. Now I haven't stood on the breaker bar,.... but. I'm scared to jump up and down on it. The last thing I want is to strip the bolt head off. I'm now thinking about one of those hand impact tools that you hit with a hammer.
Any advise?
Thanks
Doug

[304065]

Are you talking about the pulley bolt or a flywheel bolt?

[TxSquash]

The pulley bolt.
I've locked my flywheel using a case bolt and a bolt in the FW with a strip of metal. But I can't budge the Pulley bolt.

[304065]

Doug,

Depending on whether your car has a/c or not, the tightening torque is either 60 ft-lb or 125 ft-lb (the higher figure is for the longer bolt for a/c pulley). So you should figure it will take at LEAST that to break loose, possibly more if there's a higher friction component caused by corrosion. The pulley sits in the engine cradle which can fill up with dirt, moisture etc., so corrosion is possible.

I think you are on the right path with a breaker bar and an extension. I would NOT use the manual impact wrench, you don't want to load the threads axially. A good tight-fitting socket, loads of PB blaster into the threads and a long extension should break it loose.

[trconway]

Try the new stuff that's out that freezes first then applies loosener. I saw it on Two Guys Garage. Made by CRC called Freeze Off. I have seen it at Auto Zone.

[TxSquash]

Yep, it's an A/C car.
But you wouldn't take a hand impact to it, your afraid it might load the threads axially (what ever that means?) OK.

Might try the Freeze Off stuff (thanks!), and guess I'll stand on the breaker bar. Hope I'm not posting soon under the title " How to Drill Out a Pulley Bolt".


Thanks

[David E. Clark]

The article Stubborn Bolt/Stud Removal on Your BMW has some good ideas from Wayne's other book. Good luck.

[sjf911]

Try a bigger impact wrench. Some of the cheaper ones don't have the torque to get the nut off. I ended up having to get a heavier duty gun to get mine off.

[Superman]

I enjoy removing those high-turque nuts the old fashioned way. Of course, this sometimes requires a bit of room to work, but I sometimes use a jackstand or something similar to hold the 'knuckle' of the breaker bar. If the flywheel is safely and securely locked, then this is just a matter of using a good six-point socket and some major force. I have a five-foot piece of steel pipe I slip over the breaker bar. That gives me enough leverage to get near or over 500 lb/ft of force. When they break loose, they SNAP. Assuming your socket is a good one that fits well and is not allowed to shift, and assuming your breaker bar handles the torque one of two things will happen. Either the bolt will loosen.......or the entire head will snap off. Either way, the pulley comes off.

[Jim Sims]

The underside of the screw head has teeth, from another thread:

In most of the early 911's prior to 1978 the crankshaft pulley screw was a M12x 1.5 x 22 mm long hex head plated cap screw of strength class 8.8 (PN 900.083.001.02) and it was used with a 12mm spring or wave washer (PN 900.028.014.01). This screw could only be tightened to 80 Nm or 59 ft-lbs due to it's strength class. This combination was used for both A/C and non-A/C equipped engines. A spring or wave washer is almost worthless as a fastener locking appliance so it is interesting to note that in the mid-year Turbo's and Carreras with A/C that the pulley screw changed to PN 999.093.005.02 (also M12x 1.5 x 22). This screw is of the "Durlok" form (http://www.franciskirk.com/screws.html) and is of strength class 12.9; this screw is tightened to 170 Nm or 125 ft-lbs (which is higher than a normal plated class 12.9 screw tightening torques of 140 Nm or 103 ft-lbs) due to the Durlok locking features consuming some of the tightening torque. A spring washer was not shown being used with this screw. Beginning in 1978 the spring washers were not being used on any of the pulleys but the pulley screw for all cars (through 1989) was the 999.093.005.02 part number.

[TxSquash]

Wow! ... you guys really know your screws.
Ok, I'm going after it with my 1/2'' breaker bar and 6 point impact socket and a pipe thats long enought to reach into my neighbors yard. Oh, and lots of PB Blaster.

Thanks

[88911coupe]

possibly a stupid question but this bolt is not reverse threaded is it? I'm using an electric impact wrench with no luck and suddenly started thinking may this thing is reverse threaded...

[aigel]

Originally Posted by sjf911

Try a bigger impact wrench. Some of the cheaper ones don't have the torque to get the nut off. I ended up having to get a heavier duty gun to get mine off.

+1

Also get an impact socket with no adapters between the gun and the socket. Make sure you have full 100+ psi (and no regulator is cutting flow). There is no way this isn't coming off with a good impact. The advantage if the impact is shock - you are much less likely to break a bolt with an impact than by standing on a breaker bar ...

George (IR - 600 ft/lb)

[88911coupe]

George, bigger impact may be in order but I still want to confirm this is not left hand threaded or reverse threaded or whatever it's called. I recall this being a complete PITA to remove before but I did manage to get it removed. Just want to make sure I'm not tightening the darn thing, thinking I'm loosening it.

[wdfifteen]

Originally Posted by TxSquash

Wow! ... you guys really know your screws.
Ok, I'm going after it with my 1/2'' breaker bar and 6 point impact socket and a pipe thats long enought to reach into my neighbors yard. Oh, and lots of PB Blaster.

Thanks

If you haven't gone shopping yet - get a 3/4" bar and socket. My 200lb carcass on the end of a 3 foot bar snapped the square drive right off of Craftsman 1/2 bars. I've been using a Craftsman 3/4" breaker to tighten and remove 356 gland nuts and axle nuts (400 lb-ft) for 20 years and it's bent and mangled, but it hasn't broken yet.

[Geronimo '74]

No airco here, but that sucker was TIGHT!
I locked the flywheel and used a breaker bar. Man, I had to pull hard!! Once it came loose it was easy.
Try some good penetrating oil (like you haven't tried that already)

Good luck!

[88911coupe]

I have a 3/4" breaker bar but still trying to confirm it's not reversed threaded. I recall there was something that is reverse thread but am drawing a blank. I can get some serious torgue on the thing but I want to make sure which way it turns...

[boyt911sc]

Originally Posted by TxSquash

I can't get the puppy off! PT Blaster, heat, impact wrench. I've put a breaker bar on it and a pipe extension. Now I haven't stood on the breaker bar,.... but. I'm scared to jump up and down on it. The last thing I want is to strip the bolt head off. I'm now thinking about one of those hand impact tools that you hit with a hammer.
Any advise?
Thanks
Doug

Doug,

I had an SC engine disassembled recently and used an impact wrench to remove the crankshaft pulley bolt. It came loose after a couple of squeeze on the trigger. In case someone had put on some loctite on the bolt's thread, try to apply some heat to break the chemical bond.



The torque spec for the crank pulley bolt is 59 ft-lb and assuming it was torqued twice as much @ 120 ft-lb, a good impact wrench could conveniently undo it. Or an extra long breaker bar could easily help unbolt a 200 ft-lb torqued fastener too. Keep us posted of your progress.

Tony

[Jim Sims]

"The torque spec for the crank pulley bolt is 59 ft-lb"

If the crank pulley bolt is of the Durlok form (serrations under the head - Porsche OEM PN 999.093.005.002) the tightening torque is 120 ft-lbs, 1978 through 1989.
I would not be surprised if 200 ft-lbs is required to loosen it.


The bolt is right-hand thread: when looking at the head of the bolt, turn counterclockwise to loosen.

[sjf911]

I had to go to a 1/2" impact wrench rated at 600 ft lbs to get mine off. I struggled with lesser tools for some time then broke down and bought the bigger wrench. It spun off on the first try.