cam chain tensioner shoe - can it be improved?

[silverd2]

Originally Posted by gOOOOran I forgot to post the part number for the A6 variator I have. 058 109 088 E ETKA matches that number with late 90's, maybe 2000, 1.8L base engine.

[gOOOOran]

Thanks! thats good to know. I was mistaken, I can move the bottom piston, there appears to be no locking pin in this variator. The bottom spring fights the motion upwards of the bottom piston, so must be some strong oil pressure to make it all move up.
Strangely, there seems to be a oil inlet into the hollow top piston too, maybe the idea is for the oil pressure to take over from the spring?
Here is a wild guess, maybe those two holes in the top piston are pressure release holes to push the top piston up to a specific position (ie tension) when oil is flowing?
I'm not sure what the metal bar is for inside the top piston?

Here are three more pictures.

[ezveedub]

I've never seen any type of looking pin. They all can compress. When you get a new one, they come compressed with the holder/tool, which is what the techs use when taking them out for replacement or other service work.

[silverd2]

Originally Posted by ezveedub

I've never seen any type of looking pin. They all can compress. When you get a new one, they come compressed with the holder/tool, which is what the techs use when taking them out for replacement or other service work.

If you read this entire thread and take a look at the diagrams, you'll notice that as long as the adjusting piston (the bottom one) is in place (at least on 40V 4.2L adjusters, including A6 40v) the pin(s) is hidden in a detent between the adjusters bore and the outer diameter of the lower piston...close hydraulic tolerance (no seals), so impossible to see....it's (they?) is there in my version.

I can assure you in the 40V the bottom piston does NOT compress with the tool...only the top (tensioning) piston. I (and others I know) have done this job and the bottom piston stays mechanically locked while out and during removal/installation >>>

http://forums.quattroworld.com/a8/msgs/55496.phtml

The adjuster in gOOOOran's post is from a 1.8L of unknown year (late '90s ?) and less than half the cost new, compared to a 4.2L version...some basic function, but different design...esp seeing that inner rod in most recent photos...plus D2 design has no visible spring on the lower piston.

[gOOOOran]

Can we source just a new or longer spring for the top tensioner? This must be a fairly common and cheap part, lots of places make springs?
I'm worried the slop in the chain could shorten the life of even a new set of pads, I would rather do both, ie, new pads and return the tension.

[silverd2]

Originally Posted by gOOOOran

Can we source just a new or longer spring for the top tensioner? This must be a fairly common and cheap part, lots of places make springs?
I'm worried the slop in the chain could shorten the life of even a new set of pads, I would rather do both, ie, new pads and return the tension.

I couldn't imagine how you'd get the correct specs on a spring, IF that is even the problem...very exacting tolerances I'm sure. My current idea of shimming it up would (theoretically) retain the proper size, rate and material.

At this point, that's just my current "wild guess" ...not to be taken too seriously yet. The drawing board is in constant flux

A lot will depend on close inspection, with a new outlook, next time i pop the valve cover. I also want to discuss the initial chain tightness with someone who's installed a new adjuster...my theory could be complete crap(?)

[silverd2]

Well here's the follow-up I promised:

1st, I learned that the Audi drawings in my past post are actually correct...the left and right adjusters have the locking pins in different places, due to reversed interior plumbing on bank 1 adjuster compared to bank 2.

The rest (and much is surprising to me) is in my QW post...long, but interesting. Things work differently than I thought...and the start-up noise is NOT what I (and others) thought it was >>>

Enjoy: http://forums.quattroworld.com/a8/msgs/65935.phtml

[gOOOOran]

Thanks for doing all this research, really impressive experiment to have the engine running with cam covers off. Now you have confirmed the chain is always under good tension, I'm only going to replace the pads on my tensioners. Good to know its not a loose chain flapping around in there.

My rattling noise only happens in cold weather (below around 4 Celsius) and only during start up.

[pocketchange]

Originally Posted by silverd2

Ask and >>>>

http://www.kpematop.com/S6/V8-5VEngine.pdf

Any help for the 4V D2?

Thanks,
pc