Belt tensioner help
 

Hi guys

Having just bought a 968 after owning a 944S2 and turbo this is my first post on this part of rennlist.

OK so I have just followed the invaluable DIY guide further down for replacing the cam chain and slipper pads without any problems.

I have come to putting on the new cam belt and refitting the cam belt tensioner and have found that I can refit the tensioner without compressing it. Its tight but I didnt expect that. Is this right?

Thanks

Rich

...
answering to the original question:
no, you should not be able to put it w/o using excessive force. Might be that the hydraulic unit has relaxed or the rod is bent ...

I don't think that was the question asked. No you should not be able to install the tensioner unless its compressed. It sounds like yours might be seized, and is not extending properly, or something else is wrong.

+1

Thanks guys

Does anyone have a picture of a fully extened unit or a measurement of the overall distance so I can compare.

Rich

To be clear, the tensioner can be installed without being compressed, but only if the belt is not on yet. If the belt is on, and the pivoting arm is on, then the extended tensioner should not be able to fit.

I mean, even when it's compressed, and there is a pin stuck in it to hold it compressed, it's still a bit tight to install it while the pivoting arm is in the way. No way it should fit when relaxed.

You might need to start asking around for a used tensioner or bite the bullet on a new one ($$$).

Apparently a new one is $150.

Can anyone tell me how far it extends from the compressed position?

Mine is extending about 10mm when not fitted to the car.

Rich

Richy, I have a used tensioner available if it turns out you need one.

Thanks Alex - you couldnt measure the overall length for me could you then I will know if I need a replacement.

Rich

There is a measurement in the shop manual but I'm not at home. If you don't have an answer by this evening, I will look it up.

If you don't want to wait, you could take the tensioner off and put it in a vise to see if it retracts and expands. It is a VERY strong spring in there and it takes a lot of force to compress.

Hi again, tensioner is already off but my vice isnt big enough to compress it. Have tried pulling it but no go.

That dimension would be appreciated later.

Cheers

Rich

I just measured 13-14mm. BTW, I use a giant C-clamp to compress this thing -- super easy to compress with this.

http://forums.rennlist.com/upload/img_4337.jpg
http://forums.rennlist.com/upload/img_4338.jpg

Fantastic - thanks turns out my tensioner must be OK as it is about the same.

I guess the only other thing it could be is that I have the wrong tensioning roller, anyone know the diameter of this?

Or any other thoughts.

Thanks

Rich

Make sure you still have the button on the tensioner. Its a piece of plastic that stick in the tensioner hole and mates to the tensioner pin.
Something is definitely not right. Its a tight fit normally. Any chance you can post pictures of your setup.
Raj

http://i267.photobucket.com/albums/i..._2205Small.jpg

As stated I managed to fit the tensioner without compressing it. It is fully extended.

I dont think there is enough tension on the belt.

Is that belt new or old?

Was the head ever machined? Does it have a OEM headgasket?

Um, I think this forums is PG...

You need to check your belt. Something is not right. From the pictures, everything looks right.
Raj

Cannot see anything wrong myself but here is the reply from a well respected garage in the UK.

Rich - you have been very observant and spotted a very important issue - but your tensioner is perfectly normal and has just reached its maximum extension at which point it stops moving. This is a dangerous situation as owners assume as it is an automatic tensioner that it will always do the job - which it does not. When the gear type sprockets on the crankshaft and camshaft (that the cam belt runs around) wear they get smaller in the middles and so even a new cam belt can sit too slack on them and the tensioner does not have enough movement to take up the tension (worn rollers and water pump pulley have a similar contributory effect). However the answer is simple if you know anyone with a lathe - you simply pull out (or knock out) the white plastic bung situated on the tensioner arm and replace it with one made to the same dimensions except perhaps 3-5 mm longer on the large diameter to make up the slack lost and enable the tensioner to work in its full range again. If you cannot get one made I could make one for you but at current hourly rates, material costs invoicing and postage - as a one off it would probably cost £50.00 + Vat - which I know is ridiculous for such a small part but we cannot be at work without recovering our costs and so this is inevitable I am afraid. Good luck,


What do you think.

Never heard that before. Sounds like a band-aid solution anyway. For that price, why not do it right and buy both pulleys. I don't buy it. Also, I have a hard time believing these parts could wear that deep.
It's easy to check. Just take measurements of both pieces. Some should be able to measure pieces to compare.
Raj

Nor me the car has only done 75k miles.

I put the idler pulley on last night which has tightened things up a bit and I think the belt is probably now at roundabout the right tension but the worry is as the belt stretches a little I will not have movement in the hydraulic tensioner to compensate.

One more question - my parts pdf is showing 2 idle rollers for the cam belt 1 for the balance belt - I have 1 for each I guess this is right?

Rich

This should help.
Thanks to clarks-garage!

https://rennlist.com/forums/members/...2513-time5.jpg

To be honest if I had gone through the workshop manual process I might not even no I have a potential problem as with the belt on, idler fitted and tensioner on the belt "feels" about right.

Its the fact I know the tensioner is at the end of its travel that concerns me.

Just to be a pain some more if anyone happens to be looking at their belts I'd appreciate if they could measure the distance between the tensioner body and the tensioning arm.

Thanks for all your help guys this forum is great.

Rich

Have you tried rotating the engine a few times?

With this sort of tension system I usually pin the tensioner and install it, put a small prybar on the tensioning lever, then spin the engine over a couple times and recheck the marks before I pull the pin and release the tensioner spring.

Also there are places in the rotation where the belt is pretty slack on the side the tensioner pulls on, rotating the cam to pull on the tensioner when you release the spring might also help.

-Joel.

C'mon Richy - it's time you changed your avatar picture to the new 968 :D

As soon as I have one it'll be there.

The day I got the car it went in my garage for chain, slippers, belts, rollers and w'pump and hasnt been since.

Should be emerging in the next day or so.

Rich

Richy, take a look at this picture. New belts, rollers etc. tensioner is uncompressed. The pin is barely out of the tensioner.

https://rennlist.com/forums/members/...7-img-2333.jpg

Hope it helps. You could also be a tooth off. Check your TDC on the bottom end and the cam pulley mark. You could be off by a tooth.
Raj

$150 for a new tensioner seems like real cheap insurance.

Convinced its not the tensioner - its the position of the arm.

Arm position can only change with a different length belt, different diameter roller or gear.

The issue is marginal, the car is now running fine but I know the tensioner is right on its limit of travel.

I've got to say may be the independant garage over here is right - I can think of no other answer.

Here is my equivalent of the pic above -

[IMG]http://i267.photobucket.com/albums/i...s/IMG_2244.jpg[/IMG]

If you beleive it's at the end of it's travel, what's going to happen as the belt stretches?

Thats my worry and problem - I either have to buy new gears or get the lengthened plastic spacer on the arm.

I would be willing to bet it's not the gears. I can't imagine gears wearing down to that level. My $$ is on the belt. What brand is it? Is it Porsche belt? I say get another and compare. Tell the parts shop that you have a situation with what they sold you and you need another replacement. Make sure its Porsche belt.
Raj

The belts a Contitech belt.

http://www.contitech.de/pages/produk...estung_en.html

I'd be interested to get a measuremt of someones car from the edge of the tensioner case to the end of the piston.

Rich

Stay away from Contitech belts, especially the bs belt. Too many documented failures!
Don't say you weren't warned. Pay a little bit more now or a lot more later. They have failed in less than 10k miles before. There goes your problem right there! They seem to work fine on bimmers, vw/audi but for some reason, don't hold up well on our cars.
Raj

Are you serious?? Everyone seems to use them overhere.

Whats recomended?

Rich

Porsche oem belts, never skimp out on them. Cheap insurance. They are Dayco last time I checked which was 2 months back.
Raj

My contitech BS belt broke at 20k miles, and it tangled into my timing belt. That one hurt my wallet.

Regardless, I think your belt is too long. I don't buy that about the gears wearing out. My '93 has 240k miles on it, and everything works perfectly with the timing belt and tensioner. I don't know how or why a belt can be too long, but it's possible. Remember, if your belt is indeed too long, and you band-aid it with a bigger white bung, your valve timing will never be right.

I've put 43k miles so far on Goodyear belts and intend to use them again. I got them through Advance Auto's online store.

What happened t the pictures?