Slipped timing belt, is it always fatal for the valves

[masood_ilyas]

This refers to Mk2 Citroen Xantia 1.9 TD Automatic with nearly 160 K on the clock.
It recently experienced Crank pulley rubber disintegration followed by slipping of timing belt with hammer drill type noises very quickly followed by no power from the engine.
Well of course to satisfy my curiousity I just had to take it apart to see what happened.
In my naive optimistic view I think the camshaft and inlet outlet valves may still be intact but I need to ask the grown ups here to see if they agree.

When I took the timing belt cover off I saw the belt itself was intact and still under tension.
I then timed the flywheel for its reference position ( hole lines up behind the starter),
The cam gear shown below allowing for parallex error is correctly timed when checked with a suitable bolt.



however the fuel pump gear appears two teeth out, its hole should be where the key is shown.

.

Am I right in thinking that there is no need to take the cylinder head off yet, a thorough cleansing and a new timing belt will get this old girl running again or is it really time for serious calculations as there is very little monetary value in the car, after 12Years of ownership sentimental values only.

Any advice as ever will be appreciated.

Thanks
Masood

[citronut]

as long as the cam and crank time up correctly and in synch to each other,
i certainly would try setting/locking it all off and sticking a new belt on,

also as long as there is no visible damage/breaks to the cam,

if i read the above correctly it is only the pump out of time/sink

[andmcit]

So is the hammer drill sound the out of timing diesel pump rather than valve slap?
That's a very rare Xantia you have there being a TD auto; the bottom end of the
engine I had in an Exclusive gave up and after x2 years I gave up trying to find a
replacement engine and gave the car to a pal who's now taken up the challenge
of getting it repaired. According to Citroen 'experts' the auto and manual XUD
engines aren't interchangeable although I'd reckon on the flywheel being the
only big difference...

[citroenxm]

Course they are interchangeable .. would they really goto the effort of making a different engine for a tiny market..

after swapping the flywheel for the auto flywheel i bet your top Xm S1 (if you have one) that it would work and fit etc..

any way.. the valves will accept ONE tooth out on the crank to cam timing but that does look like the valves and crank are timed correctly so a reset should see her working correctly again..

a lucky escape there by the looks of it..

[Xaccers]

Just take the cam cover off, that will show you if any serious damage has been done.

[citroenxm]

Useually the cam shaft breaks, this is because the valves are DIRECTLY flat over the postons, and not inclined at an angle, the cam is then directly over the valves, so connection between the piston and vlaves useually transfer the energy to the cam, resulting in a breakage in any from 1 to 3 places, and also takes out a Cam Cap... or two. Also bends the studs that hold the caps in place. If the caps are not on your side, you will know because when you tighten down a Cap it will grip the replacment cam shaft.

The issue here then is orginally the head and cap bearings are machined as a Set Match, meaning a cap direct swap wont always work but can if your lucky. A bit of sanding etc can make them fit correctly though, but time is the essence...

[masood_ilyas]

Thanks chaps.
Once fog and mist clears a bit I will have a look under the cam cover. Fingers crossed.
I am guessing here that when crank pulley rubber disintegrated the fine powder managed to find its inside the timing cover.
There are signs of fine grease like soot nearby but the timing belt itself was surprisingly clean.
I suspect it only needed a thin film of oily soot for the belt to slip over the fuel pump gear.
I hope tomorrow weatherwise it will be a much better day in North West London.

Masood

[Peter.N.]

As Paul says the camshaft invariably breaks, usually into three pieces. You should be able to tell by the sound of the engine when you turn it over with the starter, if the valves are damaged you will have very little compression so the engine will turn over much faster and more quietly than normal.

Peter

[mirafioriman]

If the cam and crank are still timed correctly I can't see how the belt can have slipped. Strange how the pump is so far out.

Strange one I'm interested to find out what has happened.

[Peter.N.]

Also - normally if the belt slips on the pump it will retard the timing which will make it difficult to start and quieter not noisier - strange.

Peter

[masood_ilyas]

I took the cam cover off today, I could not find anything broken here.
I was able to turn the crankshaft and see all all the rockers move up and down along with four definite position where I felt the compression building up.
Here are the top and side views of camshaft.



I then took the timing belt off, (where did this fluff come from)



as the belt came off the fuel pump gear, there was ping noise and the gear itself moved anticlockwise by approximately 4 teeth.
I don't know if this is normal but I could rotate by hand and it felt a bit floppy.
photos below show the two end positions where tension is felt again.








Has something broken inside the pump? PeterN Does this make any sense now.
The only explanation that fits is that the fluff got under the belt at fuelpump gear causing it to slip,
or has the belt itself weakend giving way under stress when accelarating.

I am tempted to retime the pump with a new belt and see if it will start, unless advised to the contrary.

Thanks
Masood

[Peter.N.]

The pump should normally be quite difficult to turn on the pumping part of the revolution, there shouldn't be any 'slop' in it, just stiffer in places. If it stopped and wouldn't start its possible that something has happened to the pump but I have never experienced such a failure.

Peter

[citronut]

peg it all off and fit a new belt then run it up

[reblack68]

Measure the valve clearances- a wide clearance indicates a bent valve. It's not a foolproof check but it makes you feel better about going to the effort and expense of fitting a new belt.

[citroenxm]

If the cam shaft is intact the valves will be perfect.. the cam never gets away with a pistons to valve contact because of my description above... from what is said the valves are perfectly fine...

fit a belt and you be away...