coultl

Hope you guys can help me with this one.

My 20014 A4 1.8T has a nasty engine rattle (sounds diesel)from 1500-2000 rpm. At other engine speeds it's totally absent. Here is a video:
https://www.youtube.com/watch?v=KHoe...ature=youtu.be

To me it sounds like this is coming from the timing/cams area. Could this be the timing belt tensioner or the cam chain tensioner? I did the timing belt at 80k (replaced everything) and the car is at 150k now (planning to do it again soon).

So the question is, timing chain or timing belt? Which should I start with? Can I drive it for a week while I wait for parts?

Also, is there a good DIY for the timing chain tensioner? Doe people usually replace the chain along with the tensioner?

Thank you in advance!

gsjohal

Its normaally the chain tensioner, you wouldnt get such a harsh noise from a loose timing belt. Advisable to replace the chain and tensioner together.

lyleswk

You are mixing up some terms so it's a little confusing what the problem and recommendation is, i.e., there is no "chain" involved with the camshafts aside from the chain inside the adjustor.

First, I believe that noise is the cam adjustor at the back of the engine by the firewall. You should easily be able to tell if that is what is making the noise. The tensioner is at the front of the engine. They usually make a different noise than that in the video.

Below is a link to a DIY although the pictures don't come through on my browser.

http://www.audizine.com/forum/showth...cam+tensioners

coultl

Wanted to report the problem for others who come across this thread.

It sounded like the cam chain tensioner (adjuster?) so I replaced that first. When I started it back up and the rattle from 1k to 2k rpm was still there. Nothing changed. Brutal.

Then I did the timing belt (it was almost due anyway) and found the problem. The timing belt tensioner had blow it's seal and the dampening oil was all over the front of the engine. The spring was still there so the belt had tension, but without any dampening the belt hit some kind of resonance from 1k to 2k rpm.

The frustrating part is that I could have seen this by just removing the upper cam cover and taking a few pics with my phone. The blown tensioner was a mess and it would have been easy to spot. I could have skipped replacing the cam chain tensioner. Oh well.

lyleswk

It is technically an adjustor. It uses a chain to physically move the intake cam to provide different lift depending on ECU commands; there is no tensioning, just moving. I think people often (just look at youtube) get confused on what the part really is.

Anyway, glad you got your problem sorted. BTW, how would you rate the 2 jobs in terms of difficulty?

Prospeeder

Its a tensioner for sure, theres nothing wrong about calling it that. It is a tensioner and oil pressure is controlled the change how much tensions on the chain to change cam timing. The earlier 1.8Ts have no VVT so its just the chain tensioner and looks identical except no solenoid. Calling it just an adjuster is sorta misleading, and when they fail the chain makes terrible noises because of being loose and not tensioned.

lyleswk

Well, never mind. I went and looked at the parts houses and they do call it a "tensioner". Always have to be careful with the advice you get on the web