Help! Camshaft bolt rounded off

Tommys86 · Feb 28, 2015

I was in the process of doing a cam chain replacement but I've whilst fighting with the cam pulley bolt I've managed to round it off. Anyone else made this school boy error and how did you get out of it? All ideas welcomed!

Wardy 944 · Feb 28, 2015

Welding a large nut to the head of the bolt will do the trick.

kdp · Feb 28, 2015

You could try using a socket that acts on the flats of the bolt rather than the points if you are not already.

robdimond · Feb 28, 2015

Is this the big M10 triple square?
Using a good quality bit is the trick... but too late for that!

Yes welding a nut is the best bet. If you don't have welding equipment then drill the head off. With the tension released the thread stuck in the camshaft should just wind out.

Tommys86 · Feb 28, 2015

Thanks for the ideas! Im still unsure though...

If I drill it - do you think releasing the large nut behind it might be difficult if I can't hold the cam?

Welding a nut to the rounded bolt - is that going to hold vs the break away torque?

I don't have the welding equipment / skills to hand, so thinking drill first then try welding? Or should I go for welding now as obviously drilling will reduce land/surface to weld to?

robdimond · Feb 28, 2015

The 'nut' behind it is just a washer with flats on it.

Yes if you get a large nut and fill the middle with weld it will be very strong and the heat will help release the threads.
I would just drill it if you don't have a welder. The washer will then fall off and you can get some grips on the remaining bolt.

Remember to lock the pulley to the hall trigger behind it with 3x bolts so that you don't lose the cam timing, otherwise you will need 2 dial gauges to get it right again!

Also I recommend to set the engine to 45 degrees before TDC (if you've not already removed the belt). That means if the camshafts turn there is no danger of pistons hitting valves. When you refit the cams and set them to TDC then carefully turn the crankshaft forward to TDC.

robdimond · Feb 28, 2015

Some helpful links... this is when I did the job, some tips there that I wish I knew beforehand!

https://www.porscheclubgb.com/forum/tm.asp?m=743770&mpage=1&key=camshaftòµ¦£

Here is someone who had to grind off the bolt head

http://rennlist.com/forums/968-forum/409911-diy-camshaft-chain-tensioner-pads.html

Oh... and buy yourself an expensive 8mm triple square tool (snap on, stahlwille etc.) for the camshaft bridge bolts, otherwise you are in for a world of hurt like the chap who wrote the above article!

Wardy 944 · Feb 28, 2015

You could also try using a good size set of stilsons.

Cater_Racer · Mar 1, 2015

Tom did you try getting the right sized socket? preferably working on the flats? Call me! Dad

Tommys86 · Mar 1, 2015

No I used the incorrect socket because that's what I do right? Haha yes I used the right socket

its no deep so you get poor engagement - check out the links above - happens to the best of us!

Thanks for the advice guys - got it off using a cutter and have locked the timing with the 3 screws thanks! Just need to remove what's left, is it easier to do whilst left in the engine or cam out work it in a vice / fixture?

robdimond · Mar 1, 2015

Nice one! I would have thought what was left would just twist out with some pliers with the camshaft in. I don't believe it's loctited in there or anything.

Tommys86 · Mar 1, 2015

Yeah came out no problem - probably the shock therapy off the grinder. Did need a puller for the gear though - didn't want to come willingly! Stopped as I've reassessed my tooling and definitely going to get new bit for 8mm caps - hands burnt once lessons learnt, no way I'm cutting them off!