A6 Avant 2006. So I've been working on this car off and on since 9/2022. Done a lot of work on simple things that were neglected over the years, and I didn't think any thing major was going on. Bought it cheap. Low miles great shape Florida car that headed eventually North to Georgia then Ohio then to MN.

It ran rough at first when I bought it. Thought maybe it was timing. Figure that's a repair for a shop not my level. So I started doing basic repair stuff. Then tried to start it last year. Eventually gave up didn't start. But it did run before I started working on it. Stored it over winter. Back at it now.

I'm at the point of trying get it running again and now can't get it to stay running. It stumble starts for 30 seconds then shuts off. I got it running today and kept it running only by gassing it and keeping rpms at 3K. Not lots of noise but some coming from engine area.

Last year I did a compression test on all cylinders with plugs in place. Bank 1 came in at 270psi ...all 3 cylinders. Bank 2 came in at 170 all 3 cylinders. So that was ODD. As I've tried everything with sensors etc... I decided to do compression again year later. Pulled Plugs on Bank 1 they look clean but gasoline covered. Bank 2 look to be covered in dry carbon... sign of rich mixture. So I do the test. 155psi all 3 cylinders on Bank 2 and 0 psi on Bank1 all 3 cylinders.

I have a broken chain some where don't I and the valves on the Bank 1 side are open or shot. Any help is appreciated. I'm still not sure how it could even run with no compression on Bank 1 side. OR I'm doing something wrong. Which is possible.

Thanks-JH

 

FWIW rarely do chains break. It’s usually a broken chain guide or chain tensioner that causes the timing to go out.

Would suggest to not turn engine over with the starter anymore in case timing has jumped gear teeth and valves are not bent yet. If the valves are not bent then at least you don’t have to repair the cylinder head and *simply* need a chain service.

Could use a bore scope in spark plug holes to see if piston were impacted by valves.

Could pull valve covers and rotate engine by hand and check cam shaft alignments. This would verify which cam(s) are out of time and by how much. Can jump one tooth maybe two teeth without bent valves but usually by the time three teeth jump then the valves are likely bent.

 

Thanks for the response. Scope on the way. Probably have already done damage. It has started twice while this has been on going and I'm afraid I kept the foot on the gas to keep it running last go. I did move the engine by hand before I tried starting it to ensuring nothing happened while it was in storage. And it moved with out a problem ....but I did hear some thing unnatural from Bank 1. It sounded like a "clink" once I got past like a compression cycle. I just thought it was the valve sliding off the rocker or something, but maybe it was more catastrophic. Still I can't figure how the engine would run with no compression on that side??

I'll report tomorrow and if I can get some pictures from the Amazon procured scope I will. We'll see if the resolution is there to provide any answers.
Thanks-JH

 

Best to pull the spark plugs when rotating engine by hand especially when checking for rotational obstruction. When turning the engine by hand it is normal to hear a few “clink” type sounds as the collective pressure from the opening and closing valve springs can slightly rock a cam since there is no oil pressure. Only turn the engine in the same direction as when running.

 

I may have moved it backwards short distance. But Pictures attached. I think I have an answer. Tell me what I see. I think the pistons are NOT damaged but they have pieces of valve stuck to the tops of the piston dish spots. Am I correct. The last few pictures are of the side has compression. Also shows lots of carbon issues as secondary point. THere are a lot of pictures but the ones that are clean and look good are the Bank2 456. Also the dry carbon fowled valves on that side are there as well. The images that have oily crusty valves are from the Bank 1 123 side.

Some questions then to give me direction.


1. Valves have contacted pistons. Is this correct? So head or heads need to come off?
2. Can I trust that impact didn't hurt pistons, rods, and crank.
3. Lots of carbon in other head as well. Seems like its both heads off as a minimum? Is this correct.
4. Where would I go to get it done. Are there places that rebuild Audi engines , the 3.2L. Should I just replace this thing to ensure nothing else is wrong?

Thanks-JH

 

Because of the metal plastic deformation, it appears that those marks on the outer edges of the piston heads were hits by the valves.

 

I know the images are bit grainy....but which image do you see this the most, and I assume you mean out side edge of entire piston not inside circle outside edge. Also those are chunks of valve are they not?

 

Sadly there does appear to be some witness marks on some of the piston tops. There does not appear to be any other piston or cylinder damage. The witness marks suggest both Bank1 cams are out of time and some valves are likely bent. As a final check I would pull the valve covers and rotate engine by hand to TDC and look at the cam shaft ends where the two cam lock bars would be installed, like they would be when performing a chain job. This will 100% reveal if one or both Bank1 cams are out of alignment and by how much as well as verify Bank2 cam clocking. If this engine is going to be repaired then the valve covers have to be removed anyway so nothing to lose.

The carbon buildup inside the intake valve ports is a feature of the 3.2 and all DI engines of any brand. A decarb service is considered regular maintenance for DI engines.

Search your local area for a 3.2 engine service shop for a timing chain service and cylinder head repair. Option to find a good used cylinder head and swap it vs rebuilding the existing damaged Bank1 head. Another option is find a good used 3.2 and replace the engine, but of course perform same inspections to verify engine is good and perform a timing chain service prior to installation. No point installing a good used higher mileage 3.2 without a timing service otherwise same thing will happen again. Maybe you can find a pro shop seller of a good used 3.2 with proof of timing service already done and ready to install?

When rotated to TDC then each of the two banks cam end offset notches line up with each other in order to install a cam lock bar. By looking at the clocking of the notches at TDC then it will tell you which cams are out of time and by roughly how many degrees.