Total disaster when trying to change cam belt 2.0d
 

Hi,
When trying to change the cam belt on my 2008 C70 2.0d, I stupidly took of the right hand side tensioner to get clearance to remove the upper plastic cam cover.

The tensioner is the one on the right side that is not spring loaded and that is sitting in a metal bracket and held on with a long screw to the engine block opposite to the tensioner that is spring loaded.

As a consequence the belt slackened and the crank turned. Not sure if the crank turned clock wise or anti clockwise, and not sure how many teeth it jumped.

I managed to reinstall the tensioner, but when trying to turn the engine over to reach TDC, and lock it in place at the cam and flywheel, after some turns, the engine will not turn any longer because it is out of synch and I guess some cylinder is pressing on to the valves.

How do I solve this problem ?

I removed the starter motor so I see the flywheel coggs.

Any help is greatly appreciated.
Cheers

Hi again.
Did 4 tests. Losened up the belt tensioner and rotated the crank to -1, -3, +1 and +3 cms vs the original position. Then tightened the tensioner. And turned the crank clockwise.

In all 4 tests the cam sprocket hole turned from 10:00 (original position) to 11:00 o'clock and no further...as you know the cam sprocket hole needs to rotate until approx 16:00 to be locked at TDC.

What can I do next ?

I don't have experience with your engine, so just some thoughts about how to proceed.

I would try to turn the camshaft & crankshaft independently of each other a little at a time, if the camshaft gets stopped, maybe turning the crankshaft back or forwards a little will allow a bit of forwards movement on the camshaft.

If you take the cam belt off, can you turn the camshaft sprocket forwards, then follow with the crankshaft? I don't think turning the camshaft backwards is a good idea due to possible issues with a camchain tensioner but am not certain about this. You should be able to turn the crankshaft backwards a little though, as you've already done this to some extent.

Ok, then the plan would be to:
1) loosen up the belt so that camshaft and crankshaft can move independently
2) rotate the cam and/or crankshaft back and forth so that the camshaft pin hole advances from 10 to 16 o'clock to be locked
3) hopefully and when locking the camshaft, the crankshaft can be locked also since it has got into the correct position too
4) tighten the belt and remove both pins
5) rotate the engine at least 2 complete turns clockwise and verify that the 2 pins can be inserted into the 2 slots at cam and crankshaft after rotation

If so, are there any risks that the engine be more out of alignment than at start of procedure ?

Thanks for your help.

Hopefully someone with knowledge of this engine will add some comments, but based on you points above:

1, Either loosen the belt enough so that the cam & crank can turn independently, perhaps even take the belt off.

2, I don't recommend turning the camshaft backwards.


As per my other post, I'm not an expert with this engine.

Just thought of a similar procedure....

To know the location of the cylinders I remove the 4 injectors and insert 4 wooden thin sticks into the cylinders.

I then try to turn the crank so that all 4 cylinders are more or less in the middle of the stroke so that the cam can move without touching any piston.
Then I find cam TDC and lock with pin. And then move cylinder 1 to TDC and lock flywheel.
Then i tighten the belt and remove pins and do 2 or 3 full rotations of the engine to see if i got it right.

What do you think ??

I mean pistons...not cylinders in my post above....sorry

Latest news...

Removed cylinder 1 and 2 injectors.
Inserted 2 wooden sticks...25 cm long and 3 mm thick to the cylinder holes.
Slackened the cam belt.
Turned the crank clockwise so that both wood pins were even in hight...in theory this would mean that cam can now move freely without hitting any piston, right ?
Moving the crank did not take a lot of force.

Then I got into problems and doubts...

I tried to rotate the cam clockwise from position 11:00 to 16:00 o'clock with a 16 mm spanner but noted a strong resistance....I feared putting in more force if perhaps I would mess something up.

Is the cam to move with little force or is it rather hard to rotate ?

Thanks for your help.

Finally got it right !!!

I just rotated the cam with some extra bit of force and the cam turned over and stopped to TDC by itself.
So the force pattern to twist the cam goes from easy to hard then easy...or hard then easy then hard etc depending on the position of the cram...as you would expect taking into account the cam lobes shape..you can actually feel the valve springs making resistance when turning....

Anyway...pinned down cam and flywheel to TDC with the 2 metal pins, installed and tensioner the belt, took out pins and rotated the engine 2 times (did this twice) and checked alignment again at TDC with the 2 pins...spot on !!!! What a relief !!!!

So now it's time to change the bl...y belt:mini023:

To be continueed....

Thanks all for your help and support.

Just to let you all know that we had a happy ending:_:

The car runs smoothly and with no errors.....well just a tiny one...the injector of cyl 2 is leaking a little bit....I guess I need to remove it and retighten the inlet harder....