M20 timing belt replacement - all done - thank you zoners

[Rtaylor2208]

Hi folks, trying to line up the TDC marks before removing the tensioner but not matter how many times I turn the crank I can't get it to match the picture in the wiki.

Can anyone link me some good images to comPare with?

I'm on my phone so searching is a nightmare

[Rtaylor2208]

Ps its a 2.5 m20

Here is an image of where the crank ends up when the TDC mark is lined up on the cam

http://img841.imageshack.us/i/imagerpd.jpg/

[daimlerman]

Line up the marks for the crank.

The cam should be somewhere near the mark,but on a standard cam,a tooth either way is not fatal.

I find that when fitting the new belt,it is usually a half tooth out,I am not strong enough to tension the belt by hand,so I back off the cam,fit and tension the belt,double check it lines up with both marks.

If in real doubt,remove the belt with the crank marks lined up,the turn the crank anti-clockwise a quarter turn(this pulls all pistons down the bore)line the cam up,turn the crank clockwise up to it's mark,fit the belt,release the tensioner,turn two turns of the crank,slowly...by a spanner on the crank,check that the marks all line up,tighten the tensioner,check again by turning by hand,insist that 'er indoors feeds you champagne and re-build!

[Rtaylor2208]

Malc, thanks for repsponding.

When lining up the mark between the "0" and the "T" on the mark on the lower crank case, the cam mark is about an inch away from the mark.

I have one other problem though, I cant get the lower timing belt cover off. When undoing the bolt it fowls on the crank (I am assuming the big cog is the crank), which means I cant get the bolt out far enough to release the case. Pic Below:



And here is how its been left at the moment, just incase I am missing something:

[SGP]

Hope this helps !
http://e30world.com/engine/BMW-E30-timi ... water-pump

[Rtaylor2208]

It does and it doesn't not really enough pictures.

[SGP]

I know what you're saying. The timing mark on the crank damper seems to be in a different position in their pic.

[cecotto479]

You time it, then remove the toothed wheel, then take the lower timing case off. It also looks like the crank isn't timed on the mark. The marker on the crank is around the gap in the teeth IIRC and it should line up with the mark on the cover that is just at the start of the third tooth to the right after the gap on your photo.

[SGP]

Once you're happy that it's lined up - (Unless the belt has slipped or broken it should be)
the damper has to come off.

[e30topless]

as above remove the bottom toothed wheel all will be revealed

[Rtaylor2208]

All thank you, I didn't realise the big toothed wheel came off as well.

Boyd your correct when saying the crank didn't look correct in that photo. That's where the crank ends up if the marks match up on the cam.

So as malc has said match up the crank to the TDC mark, then remove the vibration damper aka big toothed wheel, does that sound correct?

[cecotto479]

Hmmm. It could be half a tooth or a tooth out. That looks to be a lot more than that. It won't line up on every revolution. You've spun it through at least two full revsolutions?

However, if the engine is running fine now, it must be timed OK. Theres no real reason why engine has to be at TDC to change the belt. Just mark everything and ensure that the cam.and crank don't move in relation to each other and it'll be fine.

[Rtaylor2208]

With a clear head this morning I read through the wiki again and all the advice above.

One thing I realised was that when turning the crank using the 22MM spanner I was turning it anti clockwise to try an line things up.

I found that turning clockwise it would not go around two full revolutions as if it was stuck on something. This is all still with the belt and tensioner undisturbed.

I have not removed the plugs so could this just be the compression had built up an I wasn't strong enough to turn it any further? Or is it more likely the belt has slipped and the timing is out?

Starting to regret taking this on as I'm a little scared that I don't get something right and fook the engine.

[daimlerman]

Do not attempt to remove that 22mm bolt,the crank damper(that toothy thing) is held on a peg on a taper on the end of the crank.A smart tap on the back of it will fetch it off.
Certain that the end of the crank has a mark that lines up with a mark on the block.

Engine will turn over easily with the plugs out.

Be aware that turning either cam or crank with the belt off is risky,only turn the crank backwards(anti clock)a quarter turn,this drops all pistons part way down the bores so that it is now safe to rotate the cam.Using this method,put the cam on it's mark first,then bring the crank back(clockwise)onto it's mark,fit the belt.This is the method I used when I swapped cams over whilst my engine was sat on the garage floor waiting to go into it's new home.

As I posted yesterday,I find that I cannot pull the belt tight enough by hand to engage the cam pulley,it's usually about half a tooth out,so I advance the cam slightly,slide the belt on and rotate the engine,this tensions the belt and I find then that it lines up OK.

[Rtaylor2208]

Certain that the end of the crank has a mark that lines up with a mark on the block.

Malc Am I right in saying that this will only be visible once the crank damper is out the way?

Do not attempt to remove that 22mm bolt

Noted, thanks for the heads up.

[daimlerman]

Just dug my Bentley manual out;

'Check that both crankshaft and camshaft timing marks are correctly aligned as shown in fig 4-10.Check the crankshaft position by loosely installing the lower camshaft cover and the vibration damper so that the alignment of the crankshaft O/T mark can be inspected.

Install the belt beginning at the crankshaft sprocket.Install the belt in a counterclockwise direction,slipping the belt over the intermediate shaft and the camshaft sprockets,and the cambelt tensioner pulley.'

Above from the Engine section,page 16....

This differs from the way I described!
Also seems that I'm wrong regarding the marks I mentioned on crank/block.
Bet you are even more confused now....

Boyd is the voice of reason,where he says that the engine runs fine now,so removing/replacing the belt without moving the cam/crank will work fine.

Edit..

On the other hand,Haynes 815 page 30 fig 1.4 confirms my belief that there's a timing mark on the crank's nose!

[Rtaylor2208]

Cheers Malc. I had a look at both the Bently Manual and Haynes and found them not hugely explanatory in terms that I could understand.

So armed wit hthis new information I'll give it another try tomorrow night as I got stuck with the late shift today so wont get home from work till its dark.

[Rtaylor2208]

Went back out last night and tried again. With the crank now at TDC the cam is indeed 1 tooth out. So fingers crossed tonight I'll get the belt changed over.

[Rtaylor2208]

After about 6 hours of to be honest the hardest job I have taken on on the cabby the belt is finally changed. A big thank you to daimlerman, cecotto479 and topblag for all the advice on here and on the phone.

This is exactly why the zone is the only place to ask for E30 help.

Total result!!!!

[Topblag]

After about 6 hours of to be honest the hardest job I have taken on on the cabby the belt is finally changed. A big thank you to daimlerman, cecotto479 and topblag for all the advice on here and on the phone.

This is exactly why the zone is the only place to ask for E30 help.

Total result!!!!

Top Work. It's a tough job, I had a jedi master helping me in person but I learnt a great deal. 10/10.