Porsche-noob-91

I'm attempting to put in a new seal at the camshaft on a 1986 951.
Pelican parts and Clarks garage both claim that you need someone to hold a socket "over the retainer and hold the camshaft still while you use a 10mm 12-point and a breaker bar" so as to ensure the engine doesn't turn and ruins the valves.

I'm however a bit confused, because to do this work, you need to remove the timing belts, and to remove the timing belts, I put a flywheel lock on the car, meaning that the engine can't move anyway. Should I still have someone hold a socket over the retainer, while I break loose the 12-point bolt? Or can I skip the extra hold because I use a flywheel lock?

V2Rocket

no, you need a 32mm (1-1/4") wrench IIRC to counter-hold the big hex on the cam gear while breaking loose the 12pt bolt. otherwise the cam gear would just spin. the flywheel lock is irrelevant here.

make sure you seat the 12pt tool well into the bolt head - put it in there and tap it with a hammer a few times to really get it in - and an impact gun helps a lot here if you have one.
the bolt is torqued to something like 55ftlbs but with age it might be stuck twice that amount.

Dan Martinic

As V2 says.. the flywheel lock is for the crankshaft; if you have removed the timing belt, the camshaft will now turn freely and activate all the valves while the crankshaft (and pistons) is locked in place. Maybe keep the belt on while you do this as extra insurance but still use the counter-hold

And be sure to have a new 12-point bolt on hand for re-install

aventari

I don't like to use an impact to remove this, the bolt head is so shallow the vibration makes it easy to slip and strip the splines. I like to have 2 people, one to hold the wrench (I just use a big adjustable) on the cam nut against something solid while holding the big ratchet head steady so I can get good solid torque on it without the triple-square socket slipping out

Porsche-noob-91

Don't have an impact anyway.

Stupid question but in what direction should the person holding the wrench move? And how do you mean holding it against something solid?

Dan Martinic

When you're starting out, there are no stupid questions. The wrench should not move; it is keeping the cam gear from turning while you are loosening the 12-point bolt. The person holding it would be applying force in the opposite direction as the person turning the 12-point. So, clockwise.

I just do it on my own, left hand on wrench and right hand loosening the 12-point. I find it best to use leverage (pipe) on the 12-point end so I can slowly & evenly apply force. I always seem to have issues when the tool isn't long enough

Porsche-noob-91

Thank you for the explanation!
How difficult do you find it to do alone?

Dan Martinic

Loosen that bolt? Not hard at all. But, never found mine to be frozen or seized. Again, use a pipe to extend the ratchet and slowly but surely apply force.

No jerking or panic pulling!