M42 engine timing chain inspection and replacement questions

[kevin316i]

Are there any set rules with regard to the replacement of the timing chain on the M42 engine? My car has 124,000 miles on it and sounds OK, but there are no records on timing chain inspection or replacement.

Is it a case of checking chain and sprockets leaving well enough alone if they look OK? Is there much dismantling to be done to inspect the chain properly?

[pmaddy00]

Some1 in BMW garage told me that, it should be changed @ 100,000 ( might be wrong)...and I changed mine @ 134000 as it was making a load of noises (only the chain..the sprockets looked okay). I would say as long as it doesnt rattle..u shouldnt worry too much (dont know if there is another way of checking it).

[jaistanley]

I concur old boy...

If it aint broke dont fix...

Seriously, the tensioner will wear before the chain and you'll hear the rattling. It's highly unlikely the chain will ever snap unless the tensioner gives in. It's a duplex chain after all. If the tensioner wears, it'll stretch and wear the chain in no time at all due to the 'chain slap'. Perhaps you should change the tensioner components for M44 ones for peace of mind. I wouldn't though.

Jai

[kevin316i]

Thanks for the feedback guys. I guess a duplex chain is less likely to break. The records show the timing chain tensioner was replaced about 10 years ago, and there is a slight oil leak around the tensioner bolt on the side of the engine, so maybe I should replace the tensioner and this will get the oil leak sorted also, even though it's only a small one.