87 951 - crankshaft bolt and flywheel lock?
07-02-2018, 09:34 PM
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87 951 - crankshaft bolt and flywheel lock?
does the flywheel need to be locked at tdc when removing the crankshaft bolt? Or can I set tdc after loosening this bolt before installing a new timing belt and water pump?
07-02-2018, 10:03 PM
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Nordschleife Master
07-02-2018, 10:05 PM
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Must i I lock the engine at tdc prior to removing the bolt? I’d rather not lock it and set it at tdc on an engine stand. I have an impact wrench to get the bolt off no problem. I can lock it after to take care of the new belts.
07-02-2018, 10:30 PM
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been years since I've done a timing belt but IIRC the timing belt will slide around the lower pulley no problem. What am I missing? The crank bolt is 250#s torque correct? But as the OP now states the engine is out then blast away with the impact. BTW that's how I install it also.
07-03-2018, 04:41 AM
#6
I did my timing belts without using the flywheel lock, once you use the starter to bust the crank bolt loose reset everything to tdc and you can manage to get the crank bolt spinning, use a large screwdriver to hook into a flywheel tooth to recenter tdc, use vice grips on the flywheel with some other pry tool to halfway hodl it in place, and carefully remove the pulleys and belts and still keep everything in place. but it is easier with the tool.
07-03-2018, 12:21 PM
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Rainman
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the engine doesn't need to be locked at TDC to remove the bolt, but it does need to be locked.
it's torqued to 155 lbft.
once the engine is apart TDC doesn't matter until the valves start opening (cam housing goes back on).
it's torqued to 155 lbft.
once the engine is apart TDC doesn't matter until the valves start opening (cam housing goes back on).
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07-03-2018, 12:29 PM
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07-03-2018, 04:57 PM
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You can get the bolt off as long as the flywheel is locked, it doesn't need to be at TDC. But make sure you have a plan for turning the motor once that bolt is off, since it is the most common way of rotating the motor. Also, don't throw out your impact wrench if it fails to loosen that bolt. If it's been on a long time, you may need a very long breaker bar. Many people end up cutting a pipe to be as long as will fit under the hood, to slide over a big breaker bar, and even then have to sweat to get it off. Also, do yourself a huge favor and pull that bolt while the motor is still in the chassis. Once the motor is out, on a stand or whatever, if the impact fails to get it, you'll have a real challenge securing the motor in place enough to break the bolt free.
07-03-2018, 05:39 PM
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You can get the bolt off as long as the flywheel is locked, it doesn't need to be at TDC. But make sure you have a plan for turning the motor once that bolt is off, since it is the most common way of rotating the motor. Also, don't throw out your impact wrench if it fails to loosen that bolt. If it's been on a long time, you may need a very long breaker bar. Many people end up cutting a pipe to be as long as will fit under the hood, to slide over a big breaker bar, and even then have to sweat to get it off. Also, do yourself a huge favor and pull that bolt while the motor is still in the chassis. Once the motor is out, on a stand or whatever, if the impact fails to get it, you'll have a real challenge securing the motor in place enough to break the bolt free.
so so I bought his bad boy and am excited to go toe to toe with that bolt.
anyone ever used an AirCAT impact wrench? It’s supposedly rated to exert a loosening torque of over 1100 ft lbs. I guess we’ll find out.
07-03-2018, 05:50 PM
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I have a 3/4" Ingersoll Rand 1450 ft lbs. impact gun that can get a lot of these bolts, but I had one that even this gun couldn't remove. I ended up selling the crank with the pulley still on it. It probably depends more on the bolt than the impact gun at some point. I'd give that gun a decent chance. Turn up the air pressure to the max the gun can take, and use a short 1/2" hose straight off the compressor. A 50ft 3/8" hose (or smaller) or any of those home-garage coiled hoses will reduce the force of the gun. Good luck. If you run into trouble, follow Archimedes' advice. 
07-04-2018, 12:23 PM
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You never met Boltzilla! Not to frighten off the OP, since this was one in a thousand, but check out this thread and post #13 in particular.
https://rennlist.com/forums/924-931-...-still-on.html
https://rennlist.com/forums/924-931-...-still-on.html
07-04-2018, 06:48 PM
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Pb blaster or equivalent sprayed liberally a few days before I take it likely won’t do a thing? It’s either gonna fight me or not and I’ll know the first few moments once I start.