More Cambelt Change Help...

[2052006 10]

Ok, so I've got the new belt on the sprockets. Haynes says release the tensioner and then turn the crankshaft through 2 full turns. Then further turn it to bring no.1 piston to TDC on the firing stroke (then slacken/retighten tensioner).

 

However, it doesn't tell me how to check for TDC - I know this means top dead centre, but exactly how is it done? Or is this actually strictly necessary?

[suth82 0]

Remove the plug from cylinder no1 and put a something such as a socket extension bar down the hole, rotate the crank until you are on the compression stroke (air will puff out the plug hole) keep rotating until the bar reaches its highest point. You are now at TDC.

You can confirm this by removing your dizzy cap and ensuring that the rotor arm is pointing to lead no1.

 

Paul

[2052006 10]

Thanks, but does anyone know why the crank needs to be turned so that cylinder 1 is at tdc, before slackening/retightening tensioner?

[2-Pugs 57]

I'll probably get flamed for saying it, but I never do that bit. I just put the belt on, turn the engine 1 complete rev, and then recheck it.

[ablister 31]

if the timing marks line up and the engine doesn't lock up when turning it by hand then you can't go wrong.

[jas-E 1]

i normally put everything back together and turn it by hand more than once...turn it loadsa times for peace of mind...!!

[taylorspug 7]

I'll probably get flamed for saying it, but I never do that bit. I just put the belt on, turn the engine 1 complete rev, and then recheck it.

 

I agree, I dont mess around with all that either, just slip the belt on, line the timing marks up, turn 2 revolutions by hand, reline the marks/tension the belt, job done.

[2052006 10]

Thanks for the replies. When you say reline the timing marks, do you mean reline the holes in the crankshaft and camshaft sprockets? The reason I ask is that I've confused myself a bit - I have realised that I just put the belt on 'as it went', without paying attention to any markings on the actual belt (of which there are two I believe). The timing "holes" line up ok, but should I have aligned the marks on the belt itself with something?

[suth82 0]

Dont worry about the marks on the belt, just make sure that the timing holes in the cams & crank line up after 2 revolutions of the crank.

[2052006 10]

OK, thanks. I have retensioned and everything now, however, the holes don't quite match up, literally out by 1/2mm. Having tried to read old posts re this, I think I am right in saying this shouldn't be a problem - may have had the head skimmed at some time? I should add that I don't think they matched perfectly when I took the old belt off - I think I had to move the crank sprocket back a little.

 

Also can someone tell me if it's bad to move it anti-clockwise a bit rather than the usual clockwise?

 

Thanks for your help!

[2-Pugs 57]

OK, thanks. I have retensioned and everything now, however, the holes don't quite match up, literally out by 1/2mm. Having tried to read old posts re this, I think I am right in saying this shouldn't be a problem - may have had the head skimmed at some time? I should add that I don't think they matched perfectly when I took the old belt off - I think I had to move the crank sprocket back a little.

 

Also can someone tell me if it's bad to move it anti-clockwise a bit rather than the usual clockwise?

 

Thanks for your help!

 

I wouldn't advise rotating it anticlockwise, they mention this in the Haynes manual, I can only think it is because you are then pulling the tensioner side of the belt taut which if it were not done up tight would affect it's setting. Just rotate it once more and when you approach the timing holes, just gently tap your spanner/socket bar (whatever you're using) to move the crank into position a tiny bit at a time.

 

If you haven't already done so, take your spark plugs out. It makes turning the engine over a lot easier.

 

As for the 1/2mm mis-alignment, some will probably disagree but personally I wouldn't worry about that. Partly because, whenever I've taken an old cam belt off a 205 they are seldom absolutley spot on anyway

Edited May 11, 2008 by 2-Pugs

[simonb 0]

I disagree and have just fitted a vernier pulley for this same reason. What a difference this has made - it feels like a different beast. A lot quicker. The ability to adjust the cam 1 degree at a time allowed me to find the optimum for my driving style and is not as hit and miss as using the standard timing holes which always seem to be off slightly once the belt has done a few rotations.

 

If you can afford to invest in one I highly recommend it. Spending an hour or so to get it set up is well worth the effort IMHO.

[2-Pugs 57]

I disagree and have just fitted a vernier pulley for this same reason. What a difference this has made - it feels like a different beast. A lot quicker. The ability to adjust the cam 1 degree at a time allowed me to find the optimum for my driving style and is not as hit and miss as using the standard timing holes which always seem to be off slightly once the belt has done a few rotations.

 

If you can afford to invest in one I highly recommend it. Spending an hour or so to get it set up is well worth the effort IMHO.

 

That's interesting, didn't think it'd make so much difference but it stands to reason I suppose

 

Perhaps next time I will spend more time getting it spot on

[simonb 0]

My problem was that when the holes lined up perfectly (10mm bolts slid in easily), then there was too much slack at the front of the belt. Running like this was dodgy and caused the belt to slap slightly on the overrun plus, as soon as the engine started up, the additional slack was taken up and the holes no longer aligned. I initially thought that the belt could have been stretched but it was exactly the same with a new belt leading me to believe that the head has had a skim at some point. Therefore a vernier pulley was the only option as far as I could see and it has worked for sure.

 

The car pulls like a train now.