Just changed the cambelt on my 2001 Sporting Seicento. The tensioner was squealing like a thousand tortured gerbils, and sure enough, the one removed was only just able to rotate. It ran fine, but made a hideous noise til warmed up. Replaced tensioner, belt and water pump.


It's back together and seems to be running fine again. Far as I can tell it's the same as it was, but without the squealing. Revs fine, runs smoothly, idles fine cold and hot, temperature seems fine . . oh, no, wait, haven't fitted the temp gauge yet
If you want to hear it look on YouTube "My Seicento after cam belt change" by Airship17.

Anyway, why the post? Well, when I was fitting the new belt, I rotated the engine as suggested to line up the marks on the oil pump cover and the head. It has the single notch on the head for the cam pulley and the corner on the oil pump cover for the crank pulley mark as per manual pics. It lined up fine on both as far as I could see. I used an inspection mirror so I could sight across the mark on the camshaft pulley to the mark on the head, square-on.

However, when I fitted the new belt it was not possible to get the pulley marks on the engine marks but also to get the yellow lines on the belt on the pulley marks. The belt marks were out by one tooth, which left me in a bit of a quandary. Eventually I concluded that the engine marks are permanent and had to line up, whereas the belt lines could be for a different model, etc. Or the water pump pulley diameter or shaft centre could differ so more or less belt (by one tooth) between the pulleys - the pump I fitted has 24 teeth same as the old one but maybe there is a newer type with fewer and hence a smaller pulley.

Anyway, as above, it seems to be running fine, not any different than before apart from the noise is gone. Is this a known thing? Has anyone seen it before? Would it be obvious if it was a tooth out? Sorry, I didn't get pics as I was in a hurry by then. If there had been no marks on the belt I would be fine with it all . . . Comments gratefully received, thanks.

Always use the marks in the engine, If it was a tooth out you would notice a difference in engine performance it would not pull as well as usual

Thanks, that's what I thought. Weird, though . . .

Is it possible to find out from the ecu via the diagnostic port whether it thinks the cam and crank sensors are barking from the same hymnsheet?

Is your Seicento yellow by any chance?

Airship17 said:

Is it possible to find out from the ecu via the diagnostic port whether it thinks the cam and crank sensors are barking from the same hymnsheet?

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Not to my knowledge, but as you say it’s all running smoothly and there is no noticeable power drop then from my experience it’s all good.

Funny how this post has come up, as i had the same belt marks and pulley settings not being the same malarky.
I was of the thinking, well the engine timing positions are the key and thats it.
But i have had after doing my pump again an issue with the flashing EML after 2500 revs and P0300 ignition faults keep coming up.
After replacing the plugs, leads and front bank lamda sensor i still have the problem.
She's running like a dream but still flashing at me.
I guess i am once again looking at the belt/pulley positions.

Martz2001 said:

Not to my knowledge, but as you say it’s all running smoothly and there is no noticeable power drop then from my experience it’s all good.

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Thanks - I have roared around a bit more since and no apparent issues, so I think it's all good. For now . . . ?

dx90 said:

Is your Seicento yellow by any chance?

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No, black, as it happens. Does that affect the timing marks??

alfacool said:

I guess i am once again looking at the belt/pulley positions.

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I don't know if it's still a thing with the MPI engine but there was a mention somewhere about comparing marks on the flywheel (via a removable rubber plug) and the other marks. I guess the flywheel being bigger diameter than the crank pulley would make it easier to check, and you wouldn't have to take the alternator belt off.

The reason for my question about the ECU, above, was that we had a Golf where the timing slipped (it had a timing chain, but they had not bothered to key the crank sprocket to the crank, it just used 180Nm + 90 deg angle and diamond coated washers to try to keep it in the right place - I kid you not) Anyway, there, the engine light came on and the ECU was bleating something like "cam shaft and crank shaft sensors not in agreement" for a while before it all unravelled. I was wondering if this engine would say a similar thing if out by a tooth - it would be able to see, if it has a crank and a camshaft sensor, which I imagine it does.

Have you searched up about P0300 ignition faults? e.g. https://www.fixdapp.com/blog/p0300-code or http://www.autotap.com/problem6_engine_stalls.asp has an interesting section on P0300 and compares with P030x, says it's a general fault across all cylinders rather than a misfire on just one. It gives a bunch of possible reasons it could be giving P0300.


I would not have thought that this would be belt position, especially if it only happens above some rpm - but I'm only theorising here. The plugs, leads replacement was clearly a good thing to try, but maybe also stick a new/different coil on it, if cheap?


I saw some sage advice on another forum to the effect that if you get a problem of this type, immediately replace ignition components in ascending order of cost - so the plugs and leads were the right start.

Cheers.
In the last couple of years i have replaced.
Water pump.
front lambda sensor.
plugs.
coils.
Throttle body
Crank sensor.
Temperature sensor..
regular oil changes and gallons of fuel cleaner through it.
It runs ok at tick over and its fine on the road, with no signs of power loss.
So as it was the pump i replaced last, i guess i have to check the timing marks.
I have the will to get it sorted but no longer the time, so im running it as is at the moment.
Glad yours is ok now.

Oh right, that sounds epic . . .

Hope you get it sorted. If it's just started doing the P0300 thing after you did the work on it then I guess you do need to check nothing went wrong with that job. Timing marks must be something to check, I guess also anything you had to move or unplug during the proceedings.


Good luck! Hope it gives in soon.