Hi guys,

I'm new to the D3 platform and I've already fallen in love with the car. I'm used to work on much older cars as a hobby, so this is quite something else. I bought the car from a friend and it had collapsed air suspension, ABS faults, leaking exhaust, bad tires and soms other minor things. All of these are solved now, but I'm left with a rattle on cold startup sometimes. It doesn't happen every time, only 1 in every 6-8 times I do a cold start and it gets worse if the car sat for more than 24 hours.

So, from what I read on this forum the main cause is either bad tensioners or broken/clogged oil check valves. Ive already done a full engine oil flush with fresh 5W30 oil in the hopes of cleaning it up, but to no avail: this morning it rattled again on startup. Sometimes the rattle lasts 3 seconds, other times it stays until two or three times restarting the engine (after it runs approximate 2-4 sec).

So I have a couple of questions, hoping the guys with more D3-experience can help me out here:
- what's my engine code? It's a 03 A8 quattro from Germany (now in NL) with the 3.7 engine. I want to make sure I order the right gaskets and valves
- Does the engine have to come out for the tensioners? I think I read this somewhere online but know about some similar engines where the tensioners are bolted in from the side, not sure what to believe at this point
- My next plan of attack is the oil check valves, but I can't find a proper video/blog on this. I did find a video of a similar engine but would much rather have it somewhat engine-correct. Any ideas? I haven't done anything like this before so want to make sure I follow the right steps
​​​​​​
Last but not least; where do I order parts? Just regular old Audodoc?

​Any other advice or tips are very welcome, thanks!

 

This should be a similar setup and repair job as yours would be for tensioner and oil check valves: https://www.audiworld.com/forums/a8-...l-bfm-3029466/

 

Thanks for the link, this is for sure very informative and helpful. Definitely makes the job look somewhat less intimidating!

In the meantime I have done an oil flush and change with fresh grade-A Champion oil after letting all the old oil leak out (with the flush making it very thin) for over an hour. The rattle *definitely* seems a lot less harsh and goes away MUCH faster after cold startup now, but it's only been a week since the oil flush so that might be a bit early to say. I took a video of the rattle this morning today (19th of Dec) and as you can clearly hear, it disappears within 2 seconds:

However, here's a video of a few weeks ago pre-oil change. Mind you, the car had been sitting for a lot longer here and also the entire car was frozen over as it was about -3C. This is what triggered me to do some digging as it truly sounds as if the engine is in the middle of grenading itself. The noise goes away after turning it off and back on again. Warning: it sounds TERRIBLE.

Judging by the first video of this morning, is this an acceptable noise for a cold startup if it goes away within a few seconds? I'm well aware the second video is no good. If that comes back, the car goes up on the lift and I'll start swapping out the check valves ASAP.

 

That sounds to me like tensioners are gone. If you have a borescope you could examine the one on the drivers side through the oil fill cap. You may see a broken shoe. On the 4.2 its on the front of the engine and the passenger one is on the rear of the engine. If you have a stethoscope have someone else start the car and listen to each point to assess the noises. You can even feel it with your hand.

There is a short rattle, 1-2 sec at startup sometimes but the videos you share doesn't seem to be that. I would change out the check valves anyway but my gut tells me the tensioners are failing.

 

I think the engine code is BFL.

 

Looks like it yeah, but I'm used to older cars where engines have engine codes like XU10J2U, M20B25, etc. and I'm new to Audi's but it seems like Audi engine codes are just a lot shorter and more simple?


Sounds like worse case scenario. I checked in the oil filler cap with my borescope but did not find anything out of ordinary, all seems good. The noise happens whenever the car sat for more than a day now, seems to happen faster when the car is parked unevenly which makes me suspect the check valves more.

Here's 2 new video's. *I did just happen to get a CEL a few days ago, going to read it out this week to see if it points towards timing/chain. What kind of codes would indicate that it's an issue with the chain?

Video 1: here you can see the sounds most of the time goes away after 2-3 seconds

Video 2: this is a bit more worrysome.. the noise stays and sounds a lot worse, but it goes away quickly on a restart

 

Update: I've decided to open up the engine and just get it over with. To do this I have to drive the car to my shop, which is a 20 minute drive. Once there's oil pressure, the noise always dies down. But I don't want to risk breaking the engine now right before I intend to fix it. I was thinking for this last drive to the shop I should crank it without the engine turning on so that it builds oil pressure, for example by disabling fuel or spark. Once it's been cranking for like 10-20 seconds then I'd turn back on the fuel/spark and start it to drive it to the shop.

What is the most easy/forward way to go about this? I was thinking either disconnecting the crank position sensor but it seems like it's quite hard to reach without a jack (my jack is at the shop). Is the fuel pump or the fuel pump relay easy to reach?

 

Bump

 

Drive it or tow it. Up to you.

 

Remove the fuse from the injectors, and then put it in.