Timing Chain Tension

[pjenni12]

Can some one take a look and let me know if they think this chain is too slack. The screwdriver is about 8" long and just placed under the chain, there is about 8mm between the chain and tensioner.

If you turn the alternator front pully back and forth you can hear the chain slapping the plastic guides behind the front cover


http://good-times.webshots.com/photo/2635246800101323894RBUkZv_th.jpg 

Thanks
Phil

Edited by pjenni12 on Thursday 29th May 11:54

[kojak]

Pic not opening up.

Edited by kojak on Thursday 29th May 11:43

[JensenA]

kojak said:

Pic not opening up.

Edited by kojak on Thursday 29th May 11:43

Double Click it and it opens.....'fraid I can't answer your question though.

[kojak]

JensenA said:

kojak said:

Pic not opening up.

Edited by kojak on Thursday 29th May 11:43

Double Click it and it opens.....'fraid I can't answer your question though.

It does now....he's altered it.

I cant help either Phil, sorry.

Edited by kojak on Thursday 29th May 12:08

[mashhead]

pjenni12 said:

Can some one take a look and let me know if they think this chain is too slack. The screwdriver is about 8" long and just placed under the chain, there is about 8mm between the chain and tensioner.

If you turn the alternator front pully back and forth you can hear the chain slapping the plastic guides behind the front cover


http://good-times.webshots.com/photo/2635246800101323894RBUkZv_th.jpg 

Thanks
Phil

Hi mate,

Im not claiming to be an expert on the marque (yet), but usually on timing chains you need around 0.2-0.5 mm slack, but it does depend on the type of engine. My saab requires 0.2mm slack, and it has a plastic channel, on the underside of the head cover, to keep that slack from moving around too much. If its anymore than that, then i would check the tensioner, make sure that it hasnt binded somehow, if thats all fine, then the only option is to get the chain off, and check to see if it has stretched too much. If it has, then you need to replace the chain and sprokets (as they will have worn) and possibly the tensioner. If the chain is relativly new, or you have low miles and its streached out of tollerance, i would check to see that the valve springs are of the correct tensile, and inspect the cams and rods for any irregularities (lumps and bumps, digs etc)

but like i said i am not an expert on the marque (yet). But from one engine to another, stretched cam chains can point to the above issues.

Edited by pjenni12 on Thursday 29th May 11:54

[mikesr]

The AJP engine rebuild manual says you should be just able to lift the chain off the tensioner with a 12" screwdriver.

So it sounds way too slack to me. Probably time for a new chain. If you have aircon its an engine out job.

[longbow]

I agree, sounds far too slack. You probably don't need a new chain though - if you remove the tensioning bolt completely and inspect it you will see it comes apart (its sort of telescopic) and inside are tiny packing shims which set the length the the bolt. Add some more washers and hey presto, slack gone!

[pjenni12]

Thanks Longbow that was my plan, I took it to bits yesterday afternoon and found 1 shim in there. Once the cams are all back in I'll add a few more to take up the slack.