Fitting cambelt

Doc · Post by **Doc** » 30 Sep 2004, 23:42

A few days ago I pulled the 2.1 TD lump from my XM to sort out some oil leaks and change a knackered tensioner/pulley and cambelt. With the engine out the cambelt should have been a doddle, but I have come up against a problem that I have never encountered before when changing belts - and I have done quite a few over the last 17 years.
I have used correct sized locking bolts and an offset rod to lock up flywheel, fuel pump and camshaft. In this position, no. 4 cylinder should be at TDC (according to Haynes)
Now with everything locked I find the belt doesn't mesh with the fuel pump toothed wheel yet it does with the camshaft. By the time I have fed the belt in the correct order (crank, idler, fuel pump, camshaft, water pump then tensioner) the belt was just too tight to comfortably slip over the fully retracted tensioner. I only fed half the width on the toothed wheels.
When I finally managed to get the belt on, then release the tensioner THEN the locking pins, the fuel pump pins were extremely difficult to remove and the belt seemed slightly slack between the crank and fuel pump. I rotated the engine twice and tried to re-insert all locking bolts and flywheel pin. Both fuel AND camshaft were one tooth out. I then carried out the procedure again and still got the same result.
Four seperate times I have tried and I am at a loss which is annoying and embarrasing as I have never come accross this problem even working on complex diesels like Audi 2.5 TDi V6 or other makes of diesel engines.
Incidentally I have compared the new belt to the original and it matches perfectly - 149 teeth, same width and tooth alignment. I did notice the old belt was very tight to get off even with the tensioner retracted.
Any advice before my brain packs its bags and checks in to hotel Mad will be gratefully received.[xx(]
Doc

JohnD · Post by **JohnD** » 30 Sep 2004, 23:57

At first glance, it would seem to be the wrong belt, but I've just looked at some old 2.1 belts and they are indeed 149 teeth. If it's of any help, the measurement of the (old) belt is 1430mm. It might just be worth a check.

oilyspanner · Post by **oilyspanner** » 01 Oct 2004, 00:37

I have found on XUD 1.9s that its better to remove the fuel pump indexing bolts when fitting the belt and fit the belt with the pump pulley rotated slightly clockwise, i then put a spanner on the pump pulley nut and gently pull the pump anti clockwise enabling me to easily insert the indexing bolts, this gets all of the slack out of the front run of the belt to the back run where the tensioner is and may well cure your one tooth anomaly.
Stewart

Dave Burns · Post by **Dave Burns** » 01 Oct 2004, 01:19

On the 1.9 xud the idler roller (not tensioner) has large mounting holes to give a degree of adjustment, if the 2.1 is similar, time the engine with the pins, fit the belt and then push the idler roller by hand tight against the belt and nip it up, the timing positions should then line up perfectly.
Make sure the timing pins are centred in the holes in the cam and pump pulleys, and there must be no appreciable slack in the tight side (front run) of the belt, even with the tensioner released.
Dave

Doc · Post by **Doc** » 01 Oct 2004, 03:49

Thanks gents,
The(Sealey tools)locking pins are all a snug fit and the holes are in unworn condition. It just seems weird that fully locked, the belt rides up on top of the teeth and will only mesh if the locking bolt is removed which then allows the fuel pump wheel to flick back a few teeth - probably to relieve pumping forces within pump
I will measure the belt and try out the other suggestions and let you all know what happens.
Give me a timing chain any day!
Doc