Using the Bentley, AF in general, and this thread in particular -> https://www.audiforums.com/m_878938/tm.htm, I changed my driver's side tensioner due to diesel rattles. The head oil valley looks good - a tint of brown and no sludge signs at all (it is a 2.8 fed only synthetic). I was hoping to use the 1.8 tricks to reduce the time it took and save from having to undo the timing belt. No dice, even using the 3366 tool to release tension on the cam chain. [:@] On the 2.8 (30v at least), the tensioner on the driver's side is right up front next to the cam gear for the TB. Remove front of car. Really getting tired of this step. Released the TB, and just removed both cams and tensioner together. It's not like it was any harder than just one cam and the tensioner.

I painted marks on the cam chain and the sprockets to make things easy (as seen in the 1.8T instructions). Put everything back together. All that went smooth (for a change). Now the hard part:

I rotated the engine by the crank bolt multiple times to ensure no binding and to ensure the cam marks lined up at TDC each time. BUT, I found that the cam chain went slack occasioanlly throughout the cycle. In other words, as the crank rotated, it pulled the intake cam via the chain, and as I continued, the slack in the chain moved from the bottom of the tensioner to the top. In still other words, the top piston moved up and down throught the rotation of the engine! Is this normal? I know and expect the bottom (spring filled) piston to move and take up the slack, but the top piston too? Or is this where the oil maintains pressure?

Figuring this HAD to be normal (otherwise the top piston would not move), I put it back together nad put the front end on [:@] and filled with coolant and started it up. Only to hear the rattle (only on driver's side) still. [:@] I have hours into this tensioner replacement, only to not solve the problem. The money is a pisser too, but let's face it, it's an Audi, and we've put over $3500 in part into this car this year already ($1100 just for two cats and flex sections which I could not do myself, then another nearly $1000 to fix the SAI motor and two combi valves, valve cover leaks to include suction pump and pla$tic piping, and don't forget the $550 AB$ control module). Yes, we've had the Tokyo-by-night dash going (CEL, ABS, Brake) and I'm closing in on the lights and now the noises.

Is it normal during the final post-install rotation checks to have the slack show up at the top of the chain travel? What do you techs see whan you do them? Any info is greatly appreciated!!!!!


MIKE

Love the car when it is fully working. That just has not been the case lately. Gees, turn 100,000 miles and stuff really goes downhill. And we're looking for another one so she can drive that when I have to work on this one??? I'm nutz.

 

Any thoughts guys? Auditech? All you other Audi techs out there?

 

im not exactly sure but i kno mine had 0 slack when i took my head off.

 

Thats exactly how the tensioner is supposed to work, the piston moves up and down hydraulically to pull timing on the cams or advance them for emmisions purposes.

As for it still rattling, it usually takes a long time for them to stop chattering, i would also run a half a can of seafoam through the oil for about an hour to make sure the oil line to the tensioner isn't clogged.

 

Ok, final update on this one. The diesel sound when started was NOT the cam chain tensioner!!! I verified that the noise was coming from the front of the valve cover on the driver's side and was loudest at the area where the tensioner was located. It was barely audible from under the car.

All that work (and cash) to change it and the noise never went away. Seafoam'ed it, and the noise was still there. 1500 miles later and the noise was still there. Then we drove to PA and back. And pulling into the driveway, the noise was different. Bad different.

Tear it all apart and the ball bearings that are supposed to be in the relay roller where in all the crevices in the engine!! This timing belt kit had 30K miles on it. NOT happy. New kit installed along with a bunch of other "while I'm in there" parts and start it up.

Quiet as a mouse. It had all the classic sounds of a can chain tensioner, but was the relay roller. I got a replacement kit (water pump and t-stat included) from a different place, but it is the same manufacturer of the parts. Hopefully I just got a lemon of a roller. The only thing I can think is the the relay roller was vibrating the timing belt and that vibration was becoming evident at the driver's side exhaust cam, the first place that the belt goes after it leaves the relay roller. ???

Nice to have it running properly (and quietly) again though. Also nice to be able to properly post again after the site changes.

 

Good to see its running good again, but im not sure about what you're talking about when it comes to the relay roller? Are you talking about a hydraulic lifter bucket that the cams rides on? I can see that making that kinda noise, but thats extremely rare. Sorry i wasn't able to pin point it directly for you, but the DIY i wrote up was designed for the 1.8T engine. The 30V 2.8L engine doesn't have problems with the tensioners usually.
Did i instruct you to change that tensioner or did you come up with that conclusion on your own?

 

It had all the classic symptoms of a tensioner - diesel at idle, etc. The oil pressure was good. I had another thread here talking about it somewhere, but cannot find anything on it. Even searching for all posts by me does not find it. The consensus was that if oil pressure was good, but the noise was there and able to be pinpointed, it had to be the tensioner. The problem was the noise source - it was coming from the driver's side bank at the front, under the valve cover. But that was not the case.

The relay roller is the first "pulley" the timing belt goes around after the crank gear, and the ball bearings that are supposed to be between the rolling outer part and the bolted in inner part decided to take a tour of the engine bay. Best I can figure, the roller was going out and causing the slight noise. That last trip back home was all it could take and the ball bearings took off. I had not "inspected" that roller when I had slipped the belt off to do the tensioner as it had 30K miles on it. Guess I should have been more diligent in grabbing and wiggling things.




Note that the little ***** did not come out until just before we got home - the roller did NOT look like this when doing the tensioner.

 

holy crap, that makes me want to check mine asap. would you happen to have your old cam tensioner? i might need it if my roller looks good.

 

Sorry dude, it went in the metal scrap pile when it was changed. Then after the noise did not clear itself I started questioning it. Then the noise REALLY came back and I knew it was something not good. So, yes, I threw away a GOOD $550 part.

I should have recorded the noise it was making.

hiwords, my wife saw your .gif one night while I was surfing the site on the couch and we were watching TV. It was funny. "What is that? Holy cow, is that really? Why would you do that?" "What? Why do what? What'd I miss?"