someting funny with crank / camshaft / timing belt

[ChrisBarns]

Timing belt broke - (diagnosed by AA) so I started strip down to remove the head to assess number of bent valves etc.

When I removed the rocker cover I found that one of the arches the inlet rocker shaft runs in had broken so the head is scrap.

When I take the timing cover off the belt is very much intact. But, when you turn the crank the belt and pulleys etc don't move.

Is there some kind of woodruf (sp?) key or something on the front of the crankshaft that could has failed? or am i doing something stupid?

Any ideas / suggestions?

[Olivewoo]

sounds like your right (woodruf key) on the crank. have seem them go before.

[gotabmw]

which engine do you have i know the m40 has a woodruf key but not to sure about other engines

[E30BeemerLad]

M20 diagram

http://www.realoem.com/bmw/showparts.do ... g=11&fg=20

[gotabmw]

if you try turning the cam instead of the crank does it turn the crank pully but dont try to turn it to far as your valves could dig in to your pistons if the key is broke

[ChrisBarns]

It gets really strange - it now appears to have fixed itself. when i turn the the crank the camshaft now moves! I my dad and I hadn't both seen it not work before I'd think I was seeing things! No idea whether the timings right though.

[gotabmw]

sounds rather dodgy to me id strip off the cam belt and pullys and have a good check or if you dont want to just try and start it up and if it makes lots of nasty noises buy a new engine id prefer the first option myself

[koos]

Hi mate, are the teeth all present? I've seen it before when the teeth come off the belt but the belt is still intact. On this perticular vehicle the part of the belt where the teeth came off had got to the crank pulley and stayed there. When cranked over the crank would spin but the cam would stay in one place.
Just a thought.
Mitch

[boybimmerm3]

It could have stripped some of the teeth off the cambelt. Would remove the belt and inspect. Have a look at the valve timing first to see if its moved.

[ChrisBarns]

you are all correct. Its like "air crash investigations" here.

a 20cm stretch of the cambelt had lost its teath. while fiddling i must have moved it onto the toothed part, allowing it to work. For a bit.

Anyway several valves very bent, bit of head broken off. So i need a new head and belt. But what about the bottom end? Do we still think its woodruf key or could it just be the belt?

I'm thinking it must be safer to just buy a second hand engine as i don't know the order of the disaster. Did the teeth come off the belt, the crank pully slip or the arch in the head break and lock the camshaft?

[Ant]

Chicken and Egg time

pop another mill in there dude, the old one is best left to the pikeys...

Put a new belt and tensioner on the "new" one though, for good measure.

[gotabmw]

yeh i agree new engine is quicker than chaning head and every thing else any way and more fun