Cam Chain Tensioners

[jimbob 0]

I have a '97 VR6, I've just changed the cam chain tensioners myself. But when i got the car back togehter and running, it miss fires until about 2500revs!! My question is: is it possible that i have moved the timing one tooth on the chains even though i didn't remove the chains, would this cause it to only miss fire or would it be likely to hit the valves? Also is it possible for me to check the timing marks or change the timing without removing the gearbox again!! Or is this it possible that it's just the inlet manifold gasket as i never changed it, but it looked perfect!! Someone please help!! !amazed

[ingham 5]

get an diagnostic check ,as could be cam position sensor

[jimbob 0]

yeah good idea, will do, but is there anyway i can check i have the timing right?

[FishWick 21]

Checking the timing is easy....

1. Line up the little notch on the crank pulley with the raised mark on the oil seal casing.

2. Strip the rocker cover and manifold off.

3. Take the plugs out.

4. Drop a long screwdriver into cylinder 1. The piston should be at the top of it's stroke. If it is, look at the horizontal cut outs in the cams (airbox end), they should be dead in line and dead parallel with the head. You need to slide a bit of 4mm plate into the grooves to be sure. If you can't, the cams are on 180 out, so you'll need to rotate the engine with a 27mm socket until you can get the plate in (or the proper VW cam tool), which can take up to 4 revolutions (4 stroke engine!).

5. Once 1 is on TDC and you can slide the tool into the cam slots, look at the crank pulley again, the two marks should be aligned.

If this is the case, your engine is perfectly timed. If either or both cams are not dead parallel with the head, your timing is out.

If you advance the timing 1 tooth the engine won't pull very well past 4000 rpm. If you retard the timing 1 tooth it will be sluggish low down.

You can run the engine a tooth out no problem but it will eat the exhaust valves after a few 1000 miles.

[jimbob 0]

Nice one!! Thanks, have ordered the VW vam tool (only 7 quid!!) Not gonna drive the car anyway till i get it timed up. Hopefully it's only a tooth out and i've not done any damage! Should have come here first before i started the job! Thanks for all your help, will let you know how i get on

[FishWick 21]

You should be OK mate, you need to do a fair amount of miles with the timing a tooth out to do any lasting damage. Unfortunately being a tooth is very subtle.

[jimbob 0]

Have just done it, exhaust cam was one tooth out! Put it right and is running like a dream. Thanks