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View Full Version : Audi A7 cranking but won't start. solved



WASD
07-08-2019, 02:23 PM
Hi,

This might help some poor guy to find a solution. Went thru this myself. Audi A7 2012, 3.0tdi Quattro, 204hp, engine code CLAA (140 000 miles)

Car developed a intermittent engine wobble (like you get with a leaking injector or misfire). about a week in the whole car just shook and died. Was cranking but wouldn't start after some long cranking it sounded/ felt like it would try to start but it wouldn't, sounded like it wouldn't get enough fuel. (vcds did not show any fault codes)
Took it to 2 garages. 1st one after 2 or 3 days of checking the car out said it needed a new high pressure fuel pump, but they didn't have the specialist tools to do the job, so took it to 2nd garage (local VW/Audi specialists). After they had the car for week got a call from them saying that it's a catastrophic/ complete engine failure/ no compression. After a ridiculous Quote took the car back home as i found a used engine with warranty for less than 1/3 of the price i was quoted by the garage (was gonna do the swap myself as i had some experience).
Trusting on the specialist garage expertise was about to order that used engine when the curiosity got the better of me, i wanted to see what had happened with my failed engine which part did fail me. Pulled the engine out and started taking it apart. After pulling out 4th cylinder injector i found my problem, the copper injector seal had disintegrated and the compresion from the cylinder was being pushed out around the injector. Took the injector for testing and was told its seized in open position. Due to it being seized open the fuel pressure common rail was building up to the proper levels for it o start but high enough not to produce any fault codes.
Cleared the seating + new copper washer seal + new injector and the engine run like new. + replaced the other 5 copper washers as the looked like they are close to failure. Have dealt with quite a few failed diesel engines but never seen the copper washers fail.

3g_bishi
07-08-2019, 05:38 PM
Wow good for you, shops usually guess when they are stumped.


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robd88
07-09-2019, 05:30 AM
Wow good for you, shops usually guess when they are stumped.


Sent from my iPhone using Audizine (http://r.tapatalk.com/byo?rid=87676)Yeah. They guess with your wallet.

Nice job on the diagnosis!!

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WASD
07-10-2019, 08:39 AM
Thanks
Yea, my trust in garages was never strong but after this it's completely gone. I'm baffled of what king of diagnostics did they do to not check each cylinder compression and not catch a seized open injector. Complete and utter incompetence on there part.

15 Phantom S6
07-11-2019, 05:38 AM
Agreed, so many of the mechanics today just want to check for codes and base their diagnoses on the codes rather than actually diagnosing the problem from a mechanical/electrical standpoint... For problems occurring with no check engine light, these guys are clueless of how to properly diagnose things..

Good on you to investigate further and find the real problem, I bet when you found the actual problem, that feeling of satisfaction must have been great. Many folks would have just listened to the shop and fork over thousands of dollars..