way to fit timing belt on C20XE

[H20GTE]

I'm having problems getting the belt on the mk2 astra, the belt is fed through where it should be and I'm trying to hold the cam cogs in the right position whilst pushing the belt onto them but no luck. The tensioner is adjusted to its loose position. Is there any trick to this?

[KEV]

Re: way to fit timing belt on C20XE

The Xe is one of the easiest DOHC engines to do a belt on mate so you shouldn't be having so much trouble. Is it definetely the right belt? Check its the same length/number of teeth as the old one. It's easier if you lock the cams somehow.

[DarrenH]

Re: way to fit timing belt on C20XE

good point about the belt.

early engine uses 1 idler and 1 tensioner and a shorter belt with U shaped teeth

http://www.oddball123.pwp.blueyonder.co.uk/carstuff/20XE_cambelt_pulley_early2.jpg

later engine uses 2 idlers, 1 auto tensioner, and alonger belt with W shaped teeth.

http://www.oddball123.pwp.blueyonder.co.uk/carstuff/20XE_cambelt_pulley_late.jpg

[H20GTE]

Re: way to fit timing belt on C20XE

yeah mines early2.jpg.

in the photo, why is there a spring where the haynes shows the tensioner tool goes, on the tensioner pulley?

[KEV]

Re: way to fit timing belt on C20XE

You dont need that, it shouldn't be there, its just to help tensioning it up I would imagine.

[H20GTE]

Re: way to fit timing belt on C20XE

yeah I think locking the cams is causing the hassles. I have someone else holding the sprockets lined up with spanners. At one point I had the tensioner off completly and tried to then add it back after everything else was lined up.

[Dave bowers]

Re: way to fit timing belt on C20XE

i use a tool to lock the top pulleys together, there only a couple of quid to buy, then try fitting the belt anticlockwise, like crank then towards the exhaust cam then inlet cam ect, if needs be use a tie wrap to hold the belt on the exhaust pulley whilst you go round.

[KEV]

Re: way to fit timing belt on C20XE

I've had small problems in the past with the top timing marks on these engines as the way they line up is open to interpretation. Autodata Timing Belt books say the cam marks are set at 12 o clock but they're not. If I remember rightly the inlet and exhaust marks are just off 12 o clock and slightly lean in to they're respective marks. like this I / \E. It only takes one or two teeth out on these engines to have valve piston impact so you have to be sure. Get it on the marks, lock the engine, belt on and tension up. Then turn it over (Manually!) and make sure it goes back on all the marks and re-check tension. Don't trust the cut-out mark on the v belt pulley either. Use the proper mark on the bottom sprocket to oil pump.

Easiest way to do a belt is to get an engine on the marks and lock it, then with a white marker while the old belts on the engine mark a tooth or two on each timing related sprocket. Take the belt of and lay it over the new one and line it up tooth for tooth, transfer over the marks to the new one and line them up on the engine. Never fails. But you obviously have the old belt off already!

[H20GTE]

Re: way to fit timing belt on C20XE

i use a tool to lock the top pulleys together, there only a couple of quid to buy, then try fitting the belt anticlockwise, like crank then towards the exhaust cam then inlet cam ect, if needs be use a tie wrap to hold the belt on the exhaust pulley whilst you go round.

the lock tool, we have one for the Vectra, but thats not right for this engine, where do you get them from?

[KEV]

Re: way to fit timing belt on C20XE

the lock tool, we have one for the Vectra, but thats not right for this engine, where do you get them from?

Can you make something to lock it?

I made this last time, it looks rough made and it is, but it works:

[DarrenH]

Re: way to fit timing belt on C20XE

agree with kev. once timed up i've always found the cam sprocket marks slightly inboard of the cam cover marks.

i've never used a cam locking tool in all the 7 years i've owned and worked on XE/LET, valve spring tension on the cam lobes has always been sufficient to stop them moving. yes its helpful, but its not a key point to get the belt to actually fit.

if need be, take the tensioner right off its dowel so you have maximum slack.

if you need to lock the cam sprockets, just a pair of mole grips across the gap will do it.

the thing that used to catch me out was when you finally take the slack out of the belt, it pulls the timing marks out by a tooth, so i always used to over compensate by putting the markers out by one tooth in favour of the slack side. locking the cam wouldnt prevent that, it would just tug the crank out by a tooth instead.

[Dave bowers]

Re: way to fit timing belt on C20XE

i bought a set of locking tools and pins from britool.

[KEV]

Re: way to fit timing belt on C20XE

the thing that used to catch me out was when you finally take the slack out of the belt, it pulls the timing marks out by a tooth, so i always used to over compensate by putting the markers out by one tooth in favour of the slack side. locking the cam wouldnt prevent that, it would just tug the crank out by a tooth instead.

Yeah same for me there, when you tension it it moves the whole belt, my autodata timing belt book says that while tensioning the xe you rotate the engine through 360 degrees on the cams then 12 teeth past the marks and back again then check CS and Cam marks all line up.

[H20GTE]

Re: way to fit timing belt on C20XE

Once its all set up is it ok for the belt to run over the idler like this? It doesn't want to stay centred up on it.

[DarrenH]

Re: way to fit timing belt on C20XE

no its not ok, the picture is quite dark, but at a guess i would say you have the idler on back to front.

is the raised lip side closest to the block