MB Cambelt CHange Intervals

[AdrianH]

I think I know the answer to this but anyway... I just had the MB back from its MoT (pass no advisories ) and a fluid service. The garage (Four Circles, in Bristol) put on a note saying "Cambelt last changed in 2010". No worries, I thought, Dialynx replaced it just a couple of years ago. Turns out that was actuallyfive years ago. In that time I've done about 6000 miles. I'm very well aware of the need not to take chances with cambelts. What is the prevailing wisdom nowadays for cambelts still five years, or forty thousand miles, which ever comes first?

[BackintheFold]

Id take a look at the belt-does it look old/cracked?
Best to change it, but needs weighing up against cost of doing that.

[AdrianH]

Looks fine but have heard so many cam-belt related horror stories over the years. Probably safest to get it done.

[andya]

My kv quattro doesn't do too many miles these days, but I aim for every 5 years for a belt change. Mine is due this year - I do mine myself but am waiting till the spring when its a bit warmer! Got all the bits to tackle it including a newly painted black top cam cover.

[mikes2]

You can probably stretch to 6 years with the low miles but I wouldn't chance it much longer.

Such irregular use puts just as much strain on the belt.

I'm currently on a 5 years / 50k miles cycle on my 20v.

[droopsnoot]

I rebuilt my KV engine when the car first went off the road, and I am thinking that, as that was in 2004/5, I probably need to do a cam belt even though it's done no miles since then as I haven't finished the bodywork repairs.

At the time, the local Audi dealer loaned me the crank lock and torque multiplier tool, but frustratingly they've got rid of them now. I wish I'd taken some measurements, but I think last time I mentioned it a local forum member did get in touch to say that he'd got them and might be happy for me to borrow them.

At the time, I wondered if it would be safe to cut around half an inch off the part of the oil pump casting that forms the bottom of the cam belt cover. I didn't do it, but I think I might as it will make changes so much easier in the future - as there are loads of bolts (IIRC) holding the pump in place, it can't make much difference to the rigidity of it. I should also have modified the back cover so that it didn't block access to the water pump, while it was all in pieces. Oh well, a job for when I haven't got any rust left.

[Duffy3074]

I've got the correct locking tool if anybody needs to borrow it

[BackintheFold]

When i did the belt on my MB, i thought that removing the pulley from the front of the crankshaft would be an easier way to do it than the crank bolt. Uses about 6 smaller allen keyed bolts IIRC
I used a torque wrench borrowed from a train company to tighten it up. (crank bolt).

[droopsnoot]

Originally Posted by Duffy3074

I've got the correct locking tool if anybody needs to borrow it

Cheers, I'll keep you in mind when I get back onto the car. As I recall it, the crank locker is fairly easy to make from a bit of box section, but the issue is the torque multiplier. When chatting about this more recently, it turns out another chap I know locally is a truck mechanic, so might be able to help with a suitably-sized torque wrench.

But I figured that if I could avoid having to undo that bolt for a service item, that would be a better modification to do.

[Ringmaster]

I read that some folks cut all the way along the middle of the old cambelt, remove the front half, push the new belt on, cut away the remaining old belt, then push the new one all the way on.

Sounds too easy to be true. Are there any real risks to this method?

My C3 is due for a cam belt change and I was thinking of letting my local Audi dealer do it - they offer a 2 yr parts + labour guarantee - but no one in the dealership appears to have been born before 1990, let alone worked on a C3 (KU engine) or its contemporaries.