possible symptoms

Hi all-kind of a dumb question but what could be some of the possible symptoms of a fuel filter installed incorrectly? I mean, it may have been rotated 180 degrees while the fuel lines were off. my other question is what would some sypmtoms of a bad fuel line sensor-you know, the really cool mickey mouse clip one? I am trying to substantiate a warranty claim that VW is trying to blame me for. Anyone with any REAL experience with either situation?
Thanks in advance.

Without details about the supposed damage it is a bit hard to answer.

The Mickey Mouse clip and tee fitting attach the return line to the filter. I am not sure how that can get mixed up, but... let's suppose that one managed to do it.

If you put a a used filter, any filter, in "backwards", you basically purge the filter - partially flush out the impurities the filter has caught to date.

It is as if you ran your vacuum cleaner backwards and blew the contents of the dirt back bag out through the hose.

In the case of the diesel filter, it is conceivable that this debris makes it into the injection pump and causes damage or blockage, perhaps even at the injectors.

The return line..well, if the tee is not air tight, you will have starting issues (air leak).
There are alternative filter setups (CAT filter) where the return line is no longer shunted through the filter (the return fuel is warm and therefore warms up the fuel filter; good in the winter)and that does not cause any adverse effects.

TYo sum it up: Yes, I could see that a dirty old filter put in backwards could spell trouble; the return line attachment is a source of leakage if not properly attached.

Thanks CR, I guess I should have clarified a bit more. The filter was actually replaced with a new VW filter and filled with fuel. I know I put the lines on correctly but honestly can't remember if the mickey clip was one the fender side or the engine side when I brought it in to the dealer. I had no starting issues whatsoever but I did have a no power problem 3 or 4 times since it had been replaced. And lots of white smoke during these low power incidents. Now the dealer is telling me the lines were on backwards! The only way this would have been possible is if I had rotated the filter 180 from its original position...so it was a clean filter. I first noticed the problem two days after changing the filter. Dealer #1 found no codes but ASR/ESP and MIL lights came on prior to my arrival. And of course the problem did NOT happen while I was at the dealer. Then it happened again three weeks later (I drive it everyday) So I was wondering if the filter could have been backwards and/or the sensor with the mickey clip was malfunctioning, could I get such an intermitent problem? Incidentally, 3 dealers later with no diagnosis and the current dealership asks about my filter being changed and I said I did it and guess what....suddenly NO WARRANTY!!

BTW, I removed the hoses from the T-connection also for easier access to the black and blue O-rings on said fitting. So maybe I was an idiot for a few minutes while reassembling everything.

It would be interesting to know which codes came together with the MIL/CEL.

Correctly mounted filter: The return line from the injection pump attaches to the "thermo tee" on the filter, supplying already filtered, heated fuel back into the filter and taking any excess back to the tank. The fuel that re-enters the filter has to go through the filter element again (I do not have a cut-away pic of a filter but the location of the connectors on top of the filter suggests this; unfiltered fuel is near the filter wall, filtered fuel comes out center).

Mounted the other way round: unfiltered fuel from the tank is supplied into the filter; excess fuel is going straight into the injection pump...unfiltered.

All fuel coming from the return line passes through the filter and is filtered prior to returning to the tank.

My expertise ends here; one would have to measure whether flow rates are affected or whether you still get the required amount of fuel through that setup.
I venture out and suggest that the injection oump receives sufficient fuel with the filter mounted "backwards" because the fuel supply to the injection pump is not restricted by any filtering.

I had to go outside and look at my own filter! The mickey mouse clip and thermo tee sit on the side facing the engine.

Now...that means that my filter is mounted correctly, right? RIGHT?

After three dealers having their fingers in my engine bay, I would not be prepared to accept ANY responsibility as to whether that filter was in correctly or not. Who knows who put it in the wrong way round, provided it ever WAS in the wrong way round.
Voiding your warranty based on that seems a bit hefty.

Thanks again CR. I stopped at a reputable local diesel repair shop (they service only bigger engines like Dodge/Cummins and GM etc.) and told them my whole story. The tech I talked to said he didn't think it was likely but was unfamiliar with VW diesels so anything was possible. I just have a tough time with the fact that the first time it happened (smoke/no power/MIL and ESP lights) was 8-30-04 on a cold engine. I drove it straight to the closest dealer (how stupid, I know!) shut it off to wait for the service dept. to open 1/2 hour later. When I started it up, no lights and it seemed to be fine but I was only pulling into the service bay so I was no where near the 2000 RPM stumbling point. No codes, and they test drove it and it was fine. THREE WEEKS later, it did the exact same thing. No codes, and by the time I got to dealer #2, no problem either. I might add that it seemed to "go away" after repeated shut downs and restarts before arriving at the dealer. Dealer #2 called the VW tech assistance line and then replaced a brake light switch. The car is a manual...whatever. The whole thing just infuriates me because I spent $205 on something that they don't seem sure they fixed. Dealer #3 changed the T-fitting on the filter and hooked the hoses up correctly and bled the line. I did get the service advisor to commit to refunding my money it the problem persists as then I KNOW it was nothing I did. I even asked dealer #1 mechanic if there was anything I special I needed to do before replacing the filter. He was the one that told me about the O-rings. I also consulted Bentley service book and of course THIS trusted website. So I just don't see how it could be my fault. Incidently, YOUR filter is on correctly!!! I think I will meet my maker some day with the exact degree to which that damn thing is mounted!!!!