Make a donation

Author Topic: Possible reason for coil failures, loom damage and sometimes fire..  (Read 9574 times)

Offline volkswizard

  • Can't Read PM's Yet!
  • *
  • Thank You
  • -Given: 0
  • -Receive: 1
  • Posts: 8
    • Email
I was asked to have a look at a 2006 MY 55 reg Mk5 GTI DSG that had broken down.
Owner had bought the car a few hours ago, stopped at the services for a few mins on the way home.
Got back in it, turned key and some white smoke with a strong smell "like burning hair" came out from the bonnet/wing gap on the offside.
Engine turned over but no ignition.
The AA were called and checked fuses and ran a diagnostic scan but nothing.
Car was recovered and I started by taking the cover off the engine (always fun)
This revealed the coils and all looked OK but the smell seemed to be coming from cylinder 1 (nearest to timing belt) which looked a lot cleaner than the others (more later).
On removing the plug to the coil the damage below was visible.


You can see the pin from the terminal 1 on the coil had welded itself to the plug with the heat



Unlike with Mk4 Golf based cars, coil failure on Mk5 seems very unusual but I did a bit of googling and found other cases, both of which had involved cars that had recently been picked up from dealers by their new owners.

http://www.golfgtiforum.co.uk/index.php?topic=135800.0
http://www.golfgtiforum.co.uk/index.php?topic=125811.0

This got me wondering if this was related, what could a dealer do that would cause this?

While working on this car I noticed it had a very clean engine bay and concluded that the dealer must have cleaned it up but didn't think the engine cover could let water get passed it. Then I noticed that the seal around the filler neck was resting on the rocker cover rather than being clipped on at the top of the filler which would let water right onto coil pack #1.





THis pic shows the proximity of cylinder 1 to the filler neck.


There was also evidence of corrosion on the coil pack body which pointed to water ingress, all other coils were nice and shiney.

So it doesn't seem to be a problem that will afflict all cars randomly but cars that are washed under the bonnet AND have this seal dislodged. It could take quite a few days for the problem to manifest itself after the engine is washed and could be OK until the engine gets really hot and things expand (as it would have done  with this one parked up straight after a motorway run).

  The downside of the more reliable coils is that when they do fail the resulting damage is far more significant and beyond the realms of a roadside repair.

Repair involves a new coil (considering the suspected cause doing all 4 would be unnecessary but if someone else is paying then it's worth a go...) and the loom components from VW. Haven't ordered the parts yet so don't know if coils have a different part number now, these originals were 07K 905 715

THis is another link to someone who suffered the same failure but no mention how long they had it
http://www.mk5golfgti.co.uk/forum/index.php/topic,9982.0.html

I hope this may prevent someones pride and joy going up in smoke and also puts owners' minds at rest that theirs could at any time too. :smiley:
« Last Edit: May 09, 2010, 06:32:09 pm by volkswizard »

Offline Nickyboy

  • Always Involved
  • ****
  • Thank You
  • -Given: 2
  • -Receive: 7
  • Posts: 368
  • 2007 ED30 in Grey
Thanks for sharing that mate  :happy2:

Offline danishmkvgti

  • Just look at my post count
  • ******
  • Thank You
  • -Given: 243
  • -Receive: 154
  • Posts: 3680
    • Email
  • My Ride: http://www.mk5golfgti.co.uk/forum/index.php/topic,7823.0.html
i have fitted revision c but i believe that revision F is the latest of coilpacks  :happy2:

Over the top mod list ;o)

Chris

  • Guest
Strangly enough my no1 coil packed up on the way home from picking my car up from the selling dealer.

luckily i was only a mile from home when it when and i mananged it home on 3 cylinders

Offline volkswizard

  • Can't Read PM's Yet!
  • *
  • Thank You
  • -Given: 0
  • -Receive: 1
  • Posts: 8
    • Email
Indeed danishmkvgti it was revision F coils that arrived today from VW

The car didn't run at all, not even on the remaining 3 cylinders because 20A fuse F40 in top left hand corner (as you stand looking at it) of the board near the battery had blown which had saved the ECU and interestingly this didn't log a fault code.




Offline ub7rm

  • Won't Shut up.
  • *****
  • Thank You
  • -Given: 35
  • -Receive: 43
  • Posts: 807
Thats very interesting - and some good detective work  :congrats:

I didn't know about that seal ring around the filler cap, must be pushed down on mine so I will rectify that at the nearest opportunity.  I'm not in the habbit of washing my engine so shouldn't be a problem.  Might be worth posting this in the detailing section  :signLOL:

Another 'interesting' coincidence thats been noticed is that all the cars that we know of that this has happened to have been 55 plates - I wonder why that is?  A very slight and short lived change in the design of components perhaps?  :popcornsoda:
« Last Edit: May 10, 2010, 08:05:35 pm by ub7rm »
Sepang Blue S4 BE Avant

Chris

  • Guest
55 plate here too

Offline RedRobin

  • Just look at my post count
  • ******
  • Thank You
  • -Given: 380
  • -Receive: 442
  • Posts: 16627
  • BIALI Motorsport's Chief Horn Blower

Might be worth posting this in the detailing section  :signLOL:


....Or a new post there with a link to here.  :happy2:

Err... I go and do it now.


On facebook: https://www.facebook.com/robin.procter.50

Throbbin' Red Mk5 GTI DSG with too many mods to list - Have Fun but Safe Journeys!

Offline volkswizard

  • Can't Read PM's Yet!
  • *
  • Thank You
  • -Given: 0
  • -Receive: 1
  • Posts: 8
    • Email
All fixed now.
VW do the plug and a repair wire and my local dealer had them in stock as well as the 4 coils.
Hardest bit is getting the 3 good pins out from the old plug without damaging them but there is a Wurth tool for this.

Repair inc parts and 1hr labour + 4 coils = £200
Repair inc parts and 1hr labour + 1 coil = £100

There was something in Audi Driver mag a couple of years ago about TT 3.2 coils causing damage but they are exposed on those engines so not that surprising.

Offline RedRobin

  • Just look at my post count
  • ******
  • Thank You
  • -Given: 380
  • -Receive: 442
  • Posts: 16627
  • BIALI Motorsport's Chief Horn Blower
^^^^
A good reason for having some kind of engine cover. It's surprising how much water gets splashed into the engine bay in the 'wet season'.



On facebook: https://www.facebook.com/robin.procter.50

Throbbin' Red Mk5 GTI DSG with too many mods to list - Have Fun but Safe Journeys!

Offline Gene Hunt

  • Just look at my post count
  • ******
  • Thank You
  • -Given: 59
  • -Receive: 61
  • Posts: 2478
    • Email
Re: Possible reason for coil failures, loom damage and sometimes fire..
« Reply #10 on: May 11, 2010, 07:13:06 am »
Good write up thanks.  :happy2:
ED35. Standard factory condition.

Offline gazjones

  • Always Involved
  • ****
  • Thank You
  • -Given: 0
  • -Receive: 0
  • Posts: 82
    • Design portfolio
    • Email
Re: Possible reason for coil failures, loom damage and sometimes fire..
« Reply #11 on: May 11, 2010, 11:48:04 am »
Cheers for that.

When I cleaned my engine bay just after I got the car, I took off what I could to hose it, the rest I just used a damp cloth. It's all probably under a bonnet away from rain for a reason  :happy2: