Stumped....

B6/7 S4/RS4
#161

Oops, thanks for the bump, I’ve been meaning to update this thread. The issue was a bad driver-side tensioner from factory.

Cheetah993 describes it best:

[quote]There is a spring behind the piston that sets the tension on the chain without oil pressure. This spring makes it so the chains still have tension without full oil pressure so the timing is not messed up before the oil pressure builds. That is why they come with a retaining pin to hold them into position. I know this because I took my old ones apart to see how they worked as I am always curious. Seems to me that the spring on this one was really weak and possibly broke. No clue though unless It is pulled apart.
[/quote]
As for the discovery process, Jimmy wanted to open the valve covers again and check the adjusters, cams and whatever other mechanical parts in the area; it was where the noise was coming from. As he progressed and tested all related parts, he also figure it would be a good idea to give the timing components a once over. He eventually noted the problem with the tensioner; in this case, the piston of the tensioner was seized into place causing slack/loss of tension on the chains and thereby making a clacking noise caused by the chain, as stated in above quote.

Note the tensioner (blue arrow) post install, pre-failure

http://tapatalk.imageshack.com/v2/14/10/25/22dd56a298ffa8c9b38a2182c0ac355f.jpg

#162

Last night, I was in the process of packing my cylinder heads to send back to JHM but took a moment to give them a thorough-once over.

As I’m looking down the exhaust ports, I noticed something odd. Most of the exhaust valves were “clean” except for two specific ports, ports over cylinder #6 and #4 (iirc). The exhaust valves over #6 had an unusually high amount of carbon build-up and if anyone recalls, #6 was my cylinder with moderate scoring…hmmm.

http://tapatalk.imageshack.com/v2/14/11/14/a14f2fc738e9ce292cb2ef3aada9e0e5.jpg

I was going to offer this as a visual observation for someone to look into if they think they have scored cylinders but then realized I’m looking down exhaust ports…and unless one has headers off or the heads out, it’ll be VERY hard to examine.

Exhaust port of #4; this one was not as bad as #6:

http://tapatalk.imageshack.com/v2/14/11/14/907aedc462470416eb0a00fd4a5ac633.jpg

The remaining exhaust ports and valves looked pretty “clean” and build-up free. I’m not sure what type of educational value this build-up observation has other than a moment to look down into my heads.

#163

This is pretty good “timing” for me. heuheuheu

In the process of pulling my engine for headers and timing service…something else to look for.

How much oil are/were you consuming on average?

#164

That is interesting. One possible thing to think about is that if you have scored walls in that cylinder your going to have a little extra oil pass by the rings and when that happens that most oil will collect on the valves as they pass over them. That can cause the buildup.

#165

I started out at .5qt every 1000 and then it got progressively worse within the two-half year span. Prior to the upper rebuild, I was burning 2qts every 800 or 1qt every 4-500miles.

Pretty much my conclusion as well, it also doesn’t help that i had some leaky valve stem seals

#166

Leaky valve stem isn’t a big help

#167

I’ll post up a review of all the parts I added a little later but for the moment, I want to record some data and make notes about my oil consumption in relations to pre-timing/valve/cylinder head install and post.

I have a believe that oil consumption in MOST B6/7 S4s are not from scored cylinders but MOSTLY from aging valve stem seals and valve seals.

I’ve already put about 1500miles on the Avant since install so everything is pretty much broken in but I wanted it to be as scientific as possible so I started taking note after the tensioner fix.