BMW E30 Cambelt Snap ( HELP ) - scousegitt
My Cambelt snapped on my E30, M20 engine (BMW 320i Convertable 1991) . I bought the new belt and followed the Haynes manual to the letter for replacement. When completed the job, I tried to start engine but when cranking it sounds like any engine does if you crank it without the sparkplugs being in. The engine seems to spin over far too fast, I have checked that the Camshaft and the Crankshaft are both turning, and they seem fine. After turning engine over I re-checked the timing marks and they line up. Has anyone experienced this? And if so what is the cause?
Thanks....
BMW E30 Cambelt Snap ( HELP ) - Fullchat
When the belt snapped the camshaft and valves got out of sync with the pistons and the valves have contacted the pistons and are now bent thus not forming a seal under compression and the mixture is now blowing straight past the valves. Oh dear oh dear. Its head off time to see what has been affected. the only other possible cause is that the belt has been fittted wrongly and the camshaft timing is out. Unlikely but remotely possible.
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Fullchat
BMW E30 Cambelt Snap ( HELP ) - Fullchat
Chances are the valve seats and cylinder head are also damaged.
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Fullchat
BMW E30 Cambelt Snap ( HELP ) - scousegitt
Not good then :-( Are the parts expensive?
BMW E30 Cambelt Snap ( HELP ) - SteVee
I'd agree that the valves are probably damaged - but I would do a compression check to confirm this. Since it doesn't start at all then I suspect that the majority (all?) cylinders are affected.
The parts are not too expensive - it's the work involved in repacing them that costs.

Perhaps a 2nd hand head would be easier ?
BMW E30 Cambelt Snap ( HELP ) - M.M
Your engine is classed as an interference type where, as said above, damage is most likely.

However even some decent mechanics will admit to a daft mistake in setting up timing marks and this will give exactly the same result as you have now... a fast spin.

A fresh set of eyes from another person might be worthwhile in double double checking all is well on the set-up front.

David
BMW E30 Cambelt Snap ( HELP ) - scousegitt
I have had a second opinion and he says the belt was fitted correctly so I think it could be either the valves or the piston rings but I not sure.
BMW E30 Cambelt Snap ( HELP ) - tr7v8
A mate had one of these & it did exactly this whilst under BMW warranty. It dissapeare for a week & came back with a new head. He'd been taking the mick of my Alfa (bought at the same time) & Italian unreliability. Much gnashing of teeth on his part when I pointed out my Alfa had a Cam chain!
BMW E30 Cambelt Snap ( HELP ) - pmh
Whilst the timing belt maybe fitted correctly to the timing marks, is this one of those engines where it is possible to assemble the pulleys on the shafts incorrectly? Do you know the history, has the camshaft been taken apart in the past?

Back to basics to check the timing visually with piston movement ,TDC of No 1 valve positions and spark.


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pmh (was peter)


 

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