Cambelt Feels Slack After Change...

[Guest rick03054]

After changing my cambelt, tensioner and water pump today it feels like the belts a bit slack. I can twist it 90 degrees and then a bit more.

 

It's an 8 valve with a spring tensioner, I didn't replace the spring but it was still a job to get the mount back on the tensioner, can it be set wrong? I've turned the engine over by hand and the locking holes still line up after loads of turns. Although the white lines on the belt don't line up anymore, but I assume this is normal?

 

Just want to be sure before I start her up, I don't want it skipping teeth and I cant think of a way to adjust the tension.

[Richie-Van-GTi 70 2 Cars]

did you tighten the nut back up on the tensioner? When I done mine I loosened the large back nut, the 2 11mm nuts, got the belt on then pushed the tensioner up real tight and fastened the back nut to stop it slipping before fastening the 2 11's again

[Guest rick03054]

Yeah I tightened them all back up. How hard did you push the tightener and what with?

 

One thing I'm wondering though, the belt goes between the 2 pulleys and is engaged in the teeth, so how does the tensioner make a difference to the tension in the opposite part of the belt from where it is? The pulleys are set to the locking holes, if one pulley turned for example and took up the slack then the holes wouldn't line up anymore.

 

The fact that the holes line up after 20 odd turns of the crank makes me think I've not got it one tooth, which I assume would make the long run slack.

[Richie-Van-GTi 70 2 Cars]

try getting the belt back one tooth to tighten the front side of it right up the push the tesnion on the other side with the tensioner, thats what I done.

[Guest rick03054]

That makes sense, I'll give it a shot.

 

EDIT: Although it will mean the lines on the belt wont match the marks on the pulley, will that not make it a tooth out? It is just a little barely visible square thats the mark on the cam pulley isn't it?

Edited June 10, 2006 by rick03054

[mattmk1 0]

it doesnt matter about the lines on the belt mate, so long as your timing marks on the cam wheel and crank line up as they should.

[Guest rick03054]

Yeah, I'm just trying to get my head round the ins and outs of it, so bear with me

 

If the lines are one tooth out does that not mean theres one tooth too many or one tooth too little on the long run of the belt though?

[Guest davidt83]

I had the same problem when I tried to tension up my cambelt the other day, i did as was mentioned earlier... tighten the back nut first and then the other two 11mm ones, and then turned the engine over a few times doing as the haynes said and slackening and then tightening the belt at different points.

 

This seemed to make it a bit tighter, not entirely sure why though!

 

Dave

[j_turnell 134 3 Cars]

Just releasing the tensioner doesnt give you the correct tension completely, to further tension the belt leave the cam pully timing dowl in and then put the crank bolt back in and gently turn it clockwise this will tighten the belt further. Or lock the crank and turn the cam anti clockwise but you then have the danger of undoing the cam bolt. Once your happy with the tension then tighten the two 11mms and the 16. You should use the timing marks on the belt thats what they are there for, otherwise it will be easy to be a tooth out, you should have no problems getting them to line up. If the belt still doesnt tension then they have given you the belt for the later tensioner which has 113 teeth instead of 112.

[Guest rick03054]

James, cheers for that. I had read that on a search but was worried that turning the crank to get the tension would mean misaligning the holes.

 

And are you 100% about those belt numbers? I thought it was 113 early and 114 late, I have 113 belt and I counted the teeth on the old one and got 113 but it's tough counting them! I might cut the old belt to make it easier and make sure I've got it right.

[pug309twin40s 1]

Just releasing the tensioner doesnt give you the correct tension completely, to further tension the belt leave the cam pully timing dowl in and then put the crank bolt back in and gently turn it clockwise this will tighten the belt further. Or lock the crank and turn the cam anti clockwise but you then have the danger of undoing the cam bolt. Once your happy with the tension then tighten the two 11mms and the 16. You should use the timing marks on the belt thats what they are there for, otherwise it will be easy to be a tooth out, you should have no problems getting them to line up. If the belt still doesnt tension then they have given you the belt for the later tensioner which has 113 teeth instead of 112.

 

 

later belt has 114 teeth and early 113 teeth

[Guest rick03054]

later belt has 114 teeth and early 113 teeth

 

Nice one. Counting belt teeth sucks!

[Guest rick03054]

I did that, now the tension seems ok but the holes dont line up, just slightly out but enough so my 'dowel' won't go through.

[base-1 17]

The timing holes are the important bit, DO NOT EVER EVER rely on the marks on the belt, they are not always accurate and should never be relied on.

[Guest rick03054]

So what should I do now? The teeth are in the right place in relation to the marks (when I put it on, not now though) The holes almost line up when I turn the crank a load of times, and the tension is about right.

 

Does that mean the valves will be doing their thing a bit early? how much difference will it make? I have no idea what it would be in degrees of cam rotation, but its maybe 2 mm that the dowels hitting behind the cam pulley.

 

Am I just thinking about this too much?

[base-1 17]

Possibly, but given that it's critical to the life of your engine, that's good really

 

The holes lining up is more important, fact. Depending how far out you are you might want to re-do it, it should be possible to get it spot on. If you had it spot on before but it was missing on the marks, do it like that again.

 

Just out of interest, it will take approximately 60 revolutions to get the marks on the belt back to their original positions (if I remember right)

[j_turnell 134 3 Cars]

later belt has 114 teeth and early 113 teeth

 

Ah yeh sorry my bad.

 

As Rich says the timing holes should still match up perfectly youll notice the other holes on the bottom pully should line up with the bolt heads of the lower cam cover also when in the correct position.

[Guest ashnicholls]

how do you know whether, your engine is the earlier or later pulley. I have the same looking tensioner as i had before, how do i know which belt I need though. Do you know Paul (pug309twin40s)

[Guest rick03054]

Spring tensioner is early type - 113 teeth

 

Eccentric tensioner is late type - 114 teeth

 

Not sure on the supposed changeover time but I've read a lot about people thinking they should have one but having the other... typical

 

 

 

 

 

The holes lining up is more important, fact. Depending how far out you are you might want to re-do it, it should be possible to get it spot on. If you had it spot on before but it was missing on the marks, do it like that again.

 

I started off with the marks lined up right, and the holes lined up right, but the belt turning through about 165 degrees.

 

I now have the holes a bit out, not much, I can poke a straw through, but theres about 2mm of the bit at the back of the pulley stopping the dowel going through.

 

My 'dowel' is a 10mm drill bit by the way!

[pug309twin40s 1]

if your cant get both timing holes lined up, crank and camshaft then the timing isnt spot on and your need to redo it.

 

if the timing isn't correct you can loose power and the engine can run lumpy.

[ALEX 98 1 Cars]

The method for tensioning the timing belt up I use is.

Turn the crank by hand with the belt on, and the tensioner loose.

i.e. two 11mm nuts loose and 16mm rear nut loose.

As you turn the crank you will see the tensioner pulley move slightly back and forward.

When its at a point when the tensioner is as far forward as it goes under it's own spring. (i.e. at tightest belt point), then tighten the nuts.

I find the timing marks on the belt useful for fitting the belt.

Align both pulleys up with the dowels. fit the belt on in the right direction. then align both the timing marks up.

If you've got the right belt the timing marks will be correct. I've yet to see a belt with a miss printed timing mark on it.

I ALWAYS use the timing marks on the belt to ensure the number of teeth between the top cam pulley and bottom crank pulley are correct.

Edited June 12, 2006 by ALEX

[Guest rick03054]

So with both the dowels in, and the timing marks on the belt lined up, it all HAS to be right, this is how it started but the belt was slack. Whats the slackest you leave it with?

 

I'll have to wait untill the weekend now, but I'll give that method a try Alex. My only problem with it is that as I turn the crank surely that will put the holes out in the same way turning the cam did?

[Guest davidt83]

Well when i did mine a few days ago for the first time, I had the same problem as you Rick, when it was correctly tensioned the timing pulleys didnt quite align.

As in if I had the crank rotated so that I could fit the 10mm drill bit in the crank pulley timing hole (using the non drill end of the drill bit), the same end of the bit would not fit into the cam pulley timing hole.

But if I used the drill end of the drill bit it would go through the cam timing hole.

 

So obviously it wasnt far out, I tried a few times to get it better, but every time I would tighten the crank pulley bolt and then turn the engine over by hand a couple of times it would still be out by that much.

 

So I decided to just give it a go, and now it runs fine (not lumpy as far as I can tell, and doesnt seem to be down on power but I havent had it rolling roaded). I cant be 100% sure as I dont really know the small things I would be looking out for if it was wrong.

 

After doing a search I think if the timing was only slightly out it would just be slightly advanced or retarded depending on which way the timing was out??

 

Although after reading this I am tempted to take the belt off and try and retime it using Alex's method.

[ALEX 98 1 Cars]

Remember that the crank drives the cam pulley not the other way round, so when tuning the engine by hand use the crank pulley bolt.

Othewise you can jump a tooth by using the cam pulley.

If the white Marks on the belt align up with the marks on both pulleys the timing holes should line up with each other. If not turn the crank 180°.

Edited June 12, 2006 by ALEX

[j_turnell 134 3 Cars]

Not really sure why your having problems.

 

Personally i lock both crank and cam put the belt on and line up the timing marks, release the tensioner. Remove crank timing dowl and gently turn clockwise to improve and get correct tension on the belt then tighten 2 11mm's and the 16. Remove cam timing dowl, turn it over by hand a few times and re-check timing job done.