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maldren
Suzuka


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PostPosted: Thu Nov 24, 2016 8:57 am    Post subject: Reply with quote

scarletboarder wrote:
I'm in Stuttgart at the factory next Tuesday so will be taking along images etc just to see what they think.
Popping to the dealers with images in the morning. Not expecting a hearty welcome.


You probably know already but if you're a Porsche Club member and haven't been before, take your membership for free entry to the excellent museum.
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scarletboarder
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PostPosted: Thu Nov 24, 2016 12:52 pm    Post subject: Reply with quote

CFo wrote:
scarletboarder wrote:

Popping to the dealers with images in the morning. Not expecting a hearty welcome.


I still think you should be looking at some legal advice regarding their responsibility.


Been to the dealers, business owner unavailable and no-one knows when he's back in, surprise , surprise. Left details of the failure and will be seeking out legal advice this afternoon.
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scarletboarder
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PostPosted: Thu Nov 24, 2016 1:21 pm    Post subject: Reply with quote

poppopbangbang wrote:
I'd be very confident that is a wrist pin retaining failure on the induction or more likely compression stroke.

The tell is there is one little .....................

Happy to do you an engineers report if needs be and you can send me some pictures of the bore the failure occurred in.


Thanks for the offer Thumb



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scarletboarder
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PostPosted: Thu Nov 24, 2016 1:23 pm    Post subject: Reply with quote

Thanks for all the feedback guys Thumb

The album below shows all the images I have uploaded and some more and the 2 videos.

http://s87.photobucket.com/user/philworsley/library/Porsche%20911%20Targa
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poppopbangbang
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PostPosted: Thu Nov 24, 2016 2:23 pm    Post subject: Reply with quote

I've attached a grab from your video to this post and boxed in red the two tell tale scores on the bore. You can tell even from the video that they are too deep and too straight to have been made post failure.

The rest of the damage followed this failure due to the unconnected rod flailing around and/or the liner failing either from the pin being pushed through it or the rod smashing it.

Likely cause is wrist pin retaining clip incorrectly fitted or old clip reused and either a failure of the clip or insufficient tension to retain due to being used once already.
 



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scarletboarder
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PostPosted: Thu Nov 24, 2016 3:01 pm    Post subject: Reply with quote

poppopbangbang wrote:
I've attached a grab from your video to this post and boxed in red the two tell tale scores on the bore. You can tell even from the video that they are too deep and too straight to have been made post failure.

The rest of the damage followed this failure due to the unconnected rod flailing around and/or the liner failing either from the pin being pushed through it or the rod smashing it.

Likely cause is wrist pin retaining clip incorrectly fitted or old clip reused and either a failure of the clip or insufficient tension to retain due to being used once already.


I've made some close ups from the photos I've got. The best are below.




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scarletboarder
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PostPosted: Thu Nov 24, 2016 3:09 pm    Post subject: Reply with quote

Some extra data on the car/failure.
I was doing about 60mph at around 4-5000 rpm. The car was in auto and I did not change down at the time of failure. The car traveled for about 40 metres before stopping and was still in auto.
Engine rebuild done at 103071 miles.
The car was returned to the re-builder at 105476m where it was advised that an oil change and interim service was performed. No details were given of what was checked.
The car failed at 107630m
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CFo
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PostPosted: Thu Nov 24, 2016 3:21 pm    Post subject: Reply with quote

What did the dealers say when you popped in, OP? Edit - I've just seen that the owner wasn't available(probably hiding under his desk)

If it had been you who'd had the rebuild done I think it would be an open and shut case; you would have got something that wasn't fit for purpose and your legal relationship would be with the rebuilder under contract law.

I'm assuming a previous owner had the rebuild done, and then sold the car to the dealer? You might try to argue that the rebuilder owed future owners of the car a duty of care should they suffer foreseeable loss due the rebuilder's negligence, but I think that would be a hard one to stand up.

Legally it's much more straightforward if you can rely on contract law, so your most likely remedy is against the supplying dealer. If by any chance it was the dealer who had the rebuild done, then the dealer could claim for his loss in compensating you from the rebuilder.
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infrasilver
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PostPosted: Thu Nov 24, 2016 4:04 pm    Post subject: Reply with quote

I think the reason for the catastrophe is clear regarding the clip but why it took so long for it to fail is a mystery, I could understand 50-200 miles before it went walkabout but not sure why it would last a few thousand miles unless the clip simply failed or was misaligned but still held in somewhat, there isn't really that much sideways pressure on the clip.

I have fitted new clips and also re-used clips as there is no strain on them at all when installing and could be fitted a ton of times before any fatigue would occur. I just think the clip was misaligned on install and has took this long to shift.

See the picture below of how the clip should fit into the groove and the tab part into the space on the piston. If this wasn't aligned it may last all the miles it did but will eventually fail in the end. The clip tab could sit a few degrees off and not dislodge for some miles.



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Last edited by infrasilver on Thu Nov 24, 2016 5:07 pm; edited 1 time in total
 
  
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scarletboarder
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PostPosted: Thu Nov 24, 2016 5:05 pm    Post subject: Reply with quote

CFo wrote:
What did the dealers say when you popped in, OP? Edit - I've just seen that the owner wasn't available(probably hiding under his desk)

If it had been you who'd had the rebuild done I think it would be an open and shut case; you would have got something that wasn't fit for purpose and your legal relationship would be with the rebuilder under contract law.

I'm assuming a previous owner had the rebuild done, and then sold the car to the dealer? You might try to argue that the rebuilder owed future owners of the car a duty of care should they suffer foreseeable loss due the rebuilder's negligence, but I think that would be a hard one to stand up.

Legally it's much more straightforward if you can rely on contract law, so your most likely remedy is against the supplying dealer. If by any chance it was the dealer who had the rebuild done, then the dealer could claim for his loss in compensating you from the rebuilder.


The dealer had the rebuild done.
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CFo
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PostPosted: Thu Nov 24, 2016 5:41 pm    Post subject: Reply with quote

scarletboarder wrote:


The dealer had the rebuild done.


I would think this puts you in a strong position as almost certainly the dealer should get compensation from the rebuilder, and thus has less to lose by compensating you.
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poppopbangbang
Nürburgring


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PostPosted: Thu Nov 24, 2016 7:08 pm    Post subject: Reply with quote

infrasilver wrote:
I think the reason for the catastrophe is clear regarding the clip but why it took so long for it to fail is a mystery, I could understand 50-200 miles before it went walkabout but not sure why it would last a few thousand miles unless the clip simply failed or was misaligned but still held in somewhat, there isn't really that much sideways pressure on the clip.


Two reasons. 1) It had been "run in" for several thousand miles with a low rev limit which would limit load on the wrist pin and 2) This bank had cast iron liners fitted which when faced with a hardened steel wrist pin will last way longer than a coated ally bore especially when you consider the pin is below the oil scraper ring so this area has good lubrication. It can take a surprisingly long time for a pin in an iron bore to wear it to the point that it picks up.

infrasilver wrote:

I have fitted new clips and also re-used clips as there is no strain on them at all when installing and could be fitted a ton of times before any fatigue would occur. I just think the clip was misaligned on install and has took this long to shift.


It's more likely whoever removed them the first time over compressed them in doing so which slightly reduced their overall diameter. This diameter is critical in their ability to lock the wrist pin in place. For such a cheap component that has such a catastrophic failure mode it's best practice to consider them single use.
 
  
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deMort
Dijon


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PostPosted: Thu Nov 24, 2016 8:04 pm    Post subject: Reply with quote

I was struggleing to see how it could be a clip as i was always told its 50 miles or so till it lets go .. cheers to Pop and infrasilver and from the pictures as i can see it now especially the score marks .

Also i still hate engine rebuilds !

Never too old to learn something no matter what you do for a living ..

OP .. im still so sorry this has happened . .. but i know that an engineers report is very valuable if it goes legal .
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infrasilver
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PostPosted: Thu Nov 24, 2016 10:17 pm    Post subject: Reply with quote

poppopbangbang wrote:
infrasilver wrote:
I think the reason for the catastrophe is clear regarding the clip but why it took so long for it to fail is a mystery, I could understand 50-200 miles before it went walkabout but not sure why it would last a few thousand miles unless the clip simply failed or was misaligned but still held in somewhat, there isn't really that much sideways pressure on the clip.


Two reasons. 1) It had been "run in" for several thousand miles with a low rev limit which would limit load on the wrist pin and 2) This bank had cast iron liners fitted which when faced with a hardened steel wrist pin will last way longer than a coated ally bore especially when you consider the pin is below the oil scraper ring so this area has good lubrication. It can take a surprisingly long time for a pin in an iron bore to wear it to the point that it picks up.


I'm not disagreeing with you as I can see this has happened, the gudgeon pin (I'm in the UK) has sat there going up and down with the bore holding it in place, I get. I'm not sure if you know the whole gudgeon pin actually fully clears and goes about 2-3mm lower than the skirt of the bore at its lowest point, it hasn't picked up on the bore but gone below it and this is why I'm confused it lasted so long and had not caught the bottom of the bore earlier especially after all of those miles.
The only thing I think it could be that the speed at the bottom of it's stroke is so fast it doesn't allow the gudgeon to shift over any before once again sitting against the bore wall, maybe it had chipped away at the bottom of the bore, bit by bit until one day it just caught and that was the end.

poppopbangbang wrote:
infrasilver wrote:

I have fitted new clips and also re-used clips as there is no strain on them at all when installing and could be fitted a ton of times before any fatigue would occur. I just think the clip was misaligned on install and has took this long to shift.


It's more likely whoever removed them the first time over compressed them in doing so which slightly reduced their overall diameter. This diameter is critical in their ability to lock the wrist pin in place. For such a cheap component that has such a catastrophic failure mode it's best practice to consider them single use.


I do slightly disagree here though Laughing there is very little stress on the clip when removing or inserting (it is possible to insert with your fingers and a plastic tool) and these would last many times of removing and refitting no problem, this is where I draw my own conclusion that it wasn't the clip that failed but the clip not being fitted correctly and has made a break for freedom at some point after the engine rebuild, then it has ran for a while waiting for the inevitable.
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kurlykris
Indianapolis


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PostPosted: Thu Nov 24, 2016 10:40 pm    Post subject: Reply with quote

Wow, that is a seriously terrible circlip design Sad

Having not rebuilt one of these engines, is it not possible to fit the wrist pins and circlips to the pistons/conrods before fitting to the engine, or does the design/configuration not make this possible Question

That is what I always do with my V8`s Grin
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infrasilver
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PostPosted: Thu Nov 24, 2016 10:55 pm    Post subject: Reply with quote

Bank 1 you can fit them first then drop the conrod/piston unit into the bore but bank 2 it's not even possible to see the clip when fitting it so you have to do it blind through a 1 inch hole on the outside of the crankcase then you have a look afterwards with a tiny inspection mirror to see if you got it in.
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poppopbangbang
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PostPosted: Thu Nov 24, 2016 11:54 pm    Post subject: Reply with quote

infrasilver wrote:

I'm not disagreeing with you as I can see this has happened, the gudgeon pin (I'm in the UK) has sat there going up and down with the bore holding it in place, I get. I'm not sure if you know the whole gudgeon pin actually fully clears and goes about 2-3mm lower than the skirt of the bore at its lowest point, it hasn't picked up on the bore but gone below it and this is why I'm confused it lasted so long and had not caught the bottom of the bore earlier especially after all of those miles.
The only thing I think it could be that the speed at the bottom of it's stroke is so fast it doesn't allow the gudgeon to shift over any before once again sitting against the bore wall, maybe it had chipped away at the bottom of the bore, bit by bit until one day it just caught and that was the end.


Okay think about the angle of the rod relative to the piston little end bosses at BDC and the force this will impart on the pin. Then what it's like at the other end and where in the cycle the wrist pin load will degrade to all most zero. Then all will become clear with regards what walks where and why it doesn't pick up on the bottom of the bore.


poppopbangbang wrote:
infrasilver wrote:

I have fitted new clips and also re-used clips as there is no strain on them at all when installing and could be fitted a ton of times before any fatigue would occur. I just think the clip was misaligned on install and has took this long to shift.


It's more likely whoever removed them the first time over compressed them in doing so which slightly reduced their overall diameter. This diameter is critical in their ability to lock the wrist pin in place. For such a cheap component that has such a catastrophic failure mode it's best practice to consider them single use.


I do slightly disagree here though Laughing there is very little stress on the clip when removing or inserting (it is possible to insert with your fingers and a plastic tool) and these would last many times of removing and refitting no problem, this is where I draw my own conclusion that it wasn't the clip that failed but the clip not being fitted correctly and has made a break for freedom at some point after the engine rebuild, then it has ran for a while waiting for the inevitable.[/quote]

That's all fine until some clog handed ogre digs the clip out with a pick and bends it past the point where it is elastic. Then matey boy who is next up probably does everything just right but clip still gets out a little while later. If you can spot if it's two tenths of a mm off round by eye you're better than me Very Happy or if it's deformed from one edge being pried out and fails to clip into place as it should then you won't know until the above happens. With proper inspection of course you can use them again if you have knowledge of how they were removed but why bother when they're so cheap, it's less than £25 for a full engine set. We'll agree to disagree on this I guess but I'd always spend the 25 quid, I'd be beside myself if I didn't and one got out!
 
  
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infrasilver
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PostPosted: Fri Nov 25, 2016 12:15 am    Post subject: Reply with quote

I going from how I would uninstall/install as I think all engine builders would, care and precision but then I found these that both show you how not to do this job and the theory of a ham-fisted ogre makes more sense.

Hammer the clip into the insertion tool with a screwdriver


Open Youtube Page


How the hell does he know if the clip tab lined up?


Open Youtube Page

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steve1
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PostPosted: Fri Nov 25, 2016 7:16 am    Post subject: Reply with quote

Just a thought the two scores down the bores show the pin moving out and cutting the bores, would there not be scores between these lines as the clip would touch the bore first.
Or could the clip not have been fitted at all.
Just thinking Question
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Harv
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PostPosted: Fri Nov 25, 2016 8:36 am    Post subject: Reply with quote

I too wondered if the clip was never there while this engine ran.

Possible that the clip was either left out when piston 5 was built up or dislodged by the process of fitting the other circlip in some ham fisted way.

This is the only part of my upcoming engine build that I'm not looking forward to, though I have aftermarket Pistons which use flat circlips without the hook.

Good YouTube posts for how it should be done.
 
  
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