A4 2.0 TDI B8 - wont start when hot (??!)

[duncan cosgrove]

Hi

I've managed to acquire a really awkward problem with my A4 (2.0 TDI 143bhp, 2008 B8)

Basically the car wont start when hot. If i drive it to full engine temp, then once switched off it will fail to start until around 2 hours after (presumably when the engine is back down to min temp?), after which it will start again quite happily.

The engine sounds *slightly* reluctant on a cold start, but does start every time without fail.

When hot, it manages an awful metallic shaking effort with a lot of judder and vibration, then just dies again. The revs make it up to around 600rpm, so not quite enough to sustain the start. If i give it some accelerator, i can prolong the effort, but with the same metallic grinding sound, for about 2 seconds until it dies.

I can produce this error reliably, and have had 2 garages and a main dealer take a look at it.

The problem seems to have started after having a clutch and master flywheel (dual mass) replaced. I'm sending it back to those guys at the end of the week to have a third look at it, but i don't have much hope as i'm realizing the garage is pretty useless.

The technician at the Audi main dealership said he thought it was a 'collapsed master flywheel', but i'm struggling to see how this could only cause an issue when the engine has been running for a while - surely it would be a problem every time?? Also, with their prices, and if it is this, i need the original culprits that fitted the flywheel to sort it out rather than paying out another £1k+ to get it fixed again.

I've already had the engine temperature sensor replaced on recommendation, and that has made no difference.


Anyone come across this issue before, had it fixed, or have fixed it themselves?

I'm running out of time and money on this


Many thanks!

DC

 

[desertstorm]

Sounds to me like an issue with the starter motor, was it refitted correctly with the correct bolts when the gearbox was refitted. Was the correct DMF used ?.
If it only started after the clutch and DMF were changed than that is where you need to look. The garage that changed the clutch / DMF are probably not wanting to take it apart again as it's a big job.

Karl.

 

[Meemo]

I know someone who has the exact same issue on his 3.0tdi b8, only when hot also, might be worth watching his thread as he is actively working on fixing it:
http://uk-mkivs.net/topic/254254-sootpigs-30tdi-a4-avant/page-3

 

[banditbarron]

Have you checked cam belt torsion value with vcds?

 

[duncan cosgrove]

Yeah he doesn't seem to have cracked it yet. I've read up a lot on this and it seems different things may solve it for different folks which is unfortunate!

The garage that fitted the original clutch / flywheel have had it since friday morning. They've tried a number of things on it apparently, and as of this lunchtime when i phoned up for an update they were in the process of stripping out the gearbox, so at least they're taking it seriously. I think it was the fact that i pulled up outside their office with it running, and got them to turn it off and 'break' it that made the point clear.

Apparently it'll be another day at least before they can re-fit and test it, but if it turns out to be the flywheel i'll update that guy's thread at least to give him another angle to attack.

Bandit - i'll pass this on to the garage if they still can't fix the thing. Thanks for the suggestion - would that only affect it when hot however?

 

[Meemo]

one of you two are going to crack it soon

 

[pj123]

I'd put money on your egr valve sticking or failed. I would take it off and clean it. I think you can test using VCDS.

 

[duncan cosgrove]

How much would you put on it?

Turns out it was the Flywheel. The one in there was knackered, oil coming out everywhere.

Sorted now, works fine