Timing Chain advice

[YOLO]

Recently gave the car a once over and adjusted the valve clearances etc which quietened down the engine a lot, but now can here that the timing chain is quite noisy. Two things ive noticed with my S3 is its always had a slight rough idle,( been through the idle control valve , Air Mass etc ) and the other thing is when its put in service mode ( with a reader) the strobe light never sits steady, it bounces around a bit. Does this sound like a possible stretched timing chain ? or play in chain ?. Cars only done 35K.

Also if i do change chain , is there an upgrade or anything you guys would recommend while its in bits.

Cheers for any advice.

[mikeock64]

I'd be interested in some info on this, I had my tappers adjusted and they are wonderful. But now have a noise which sounded like the bearings had gone on the water pump, but after removing the belt and spinning the alternator and water pump, realised they were in good working order. I never thought of the timing chain.......May be?.

[Ralph S3]

I have exactly the same issue. Slight rattling noise that I don't remember prior to changing head gaskets and resetting vales and I also have the rough idle with bouncing timing light issue when in service mode. Engine has done 80k. Any suggestions gratefully received.

[GreenV8S]

I haven't tried it and it might not be practical, but I wonder whether it would be possible to detect a loose timing chain by letting the cam settle on a low point and then seeing how far you can rock the crank before the timing chain tightens enough to move the cam. I expect you'd need to compare with a known healthy engine to know how much play is normal and acceptable.

[greymrj]

Timing chains!!!!! A bad idea, dont have them on the S1, just a gear wheel the size and weight of a flywheel!

[phillpot]

Ralph S3 said:

Slight rattling noise that I don't remember prior to changing head gaskets and resetting valves .

are you suggesting the noise from the valves was "masking" the suspected chain noise prior to your work?


The timing chain is very short on the 2.9 and not a "known issue"

[Ralph S3]

Yes, I was wondering if the various improvements (no manifold leaks, adjusted tappets etc) might have masked what is a very slight rattle. To be honest it might just be normal as I know the 2.9 is a rattly engine. What is really bothering me is the slightly bumpy timing when in service mode as per the OPs comment above. The best way I can describe it is it's as if every few revolutions one of the spark plugs fires slightly late.

Ralph

[phillpot]

Personally I doubt the two issues are connected, if the timing chain is an issue at all?


Just out of interest do you get a steadier timing light reading NOT in service mode (all be it possibly the wrong reading)?


The electronics side of things is far from my strong point (not sure what is really) but could that erratic flash be the ECU sort of correcting itself every few seconds or something?

Edited by phillpot on Tuesday 7th June 16:11

[GreenV8S]

That jitter could be an indication of play in the distributor drive or within the distributor advance mechanism rather than the timing chain.

[Ralph S3]

Phillpot - yes its lumpy at idle when not in service mode.

GreenV8S - good point - I hadn't thought about the disty. I'll give that the once over.

R