CR engine HPFP analysis

oilhammer

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There are just too many to list....
This is the sharing of info thread, to post pics and possible causes.

These are from a 2009 car, not my pics and if the sender wants to be identified it is up to him.

Here is the pump taken apart. Note the left end of the part labeled 'piston' is where the little tiny roller is located.



Closeup shot of that piston's roller:



Close up shot of the shaft cam that roller rides on:



I have another one here, looks pretty much the same EXCEPT it has no signs of the rusty residue on it. In fact, it is squeaky clean inside.

This is the shaft, you can clearly see how much is worn away at the apex of the cam lobes:



And here is the little roller piston:



Sorry for the crappy focus, my camera is old and my skills are even older. But the wear marks on the roller could very well have been caused by the little roller getting turned off-square from the shaft's cam lobes.
 
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dieseldorf

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Brian, is that rust or overheated (coked) fuel?

The cam surface looks rough... clearly lost the ground surface and was wearing out, which is a source of heating :(

Are you going to be able to pull that roller out of the piston and get more pics?
 

ruking

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So to me it begs the question would a "lubricity agent" such as Power Service, etc have prevented the camshaft and roller it sits in from scoring?.

Keep in mind VW does NOT recommend lubricity agents such as Power Service, etc.
 

DoctorDawg

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Houston, we have data! Thank you, oilhammer and mystery donor! Keep it coming.

Can you share any metadata...how many miles on engine at failure, did the owner use an additive, failure mode, etc.?
 

oilhammer

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Just to clarify, the above pics were sent to me, they are not mine, this car is not in my shop, nor are any of those parts.

I do have another pump here, from another shop that was sent to me, that is apart and other than the rusty stuff, the wear looks pretty much exactly the same. The pump I have was off of a 31k mile 2009 car.
 

dieseldorf

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Did the car just die on the side of the road or was it a driveability issue?
 

El Dobro

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What keeps the piston from turning in the bore? Is there a flat?
 

740GLE

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I'd agree that the rust doesn't look like rust, but I imagine oil hammer would know rust when he sees it. Very interesting.

Also was this pump pulled from a wrecked car or was there a failure in the fuel system?
 

oilhammer

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The above pics came from a 2009 car, it died shortly after refueling. Dealer found cloudy fuel in the car, and a low pressure DTC. They replaced the fuel and filter, sent it on its way, but warned the customer there may be a problem, even though the car at that point was running fine.

It came in the next day on a hook, with the fuel system full of metal. Again, the above pics are NOT mine. :cool:
 

birkie

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Fascinating.

As I understand, the pump is supposed to have a Diamond-like carbon coating (DLC) somewhere on the piston as additional protection against our fuel here. I'm not sure if it is possible to tell with visual inspection - but do the sides of the piston look any different from the cam or roller as far as possible coatings/treatments? Is it possible that the cam and roller are not coated in this design? I'm no material scientist, so I don't know if that would even make sense.
 

oilhammer

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The piston itself looks to have a gray finish, yes. And the one I have here has that finished galded completely off both ends of the piston.

But it is the piston's little roller that looks like it went from a roller bearing to a friction bearing.... :eek:
 

dubStrom

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1st real step

Thanks from the other end of I-70 in MO. Thanks so much for digging into this.

Would be possible to take a new HPFP, modify it with higher quality internal components (cylinder sleeve, piston, roller, etc.) to make it less sensitive to lubricity variance?

You know, even if it failed in under30k miles, but without releasing metal, it would be a VAST improvement over OEM.

Alternatively, replace the entire unit with one that is manufactured to bolt in (connections/mounting same), but has either a different design, or better materials and machining??

An extremely well built unit for $1500-1800 would look pretty d@mned attractive in a few years, particularly if the rate of failure begins to creep above 1%...
 

oilhammer

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Someone in another thread eluded to the fact that the roller piston could rotate and be riding at right angles to the shaft, and sure enough, I confirmed here that yes it can, there is NOTHING I can see to keep the piston aligned properly with the shaft cams.

And that would explain the strange wear marks I have on this little roller.

Updated original post with more pics.
 

DanG144

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Brian,
I sure wish I had one to play with.

Is the only thing that keeps the roller pinned in place positive pressure from the aux fuel pump on top of the piston?
This keeps the piston driven down onto the roller?

This is what I have inferred, and why I insist that I will do my best to never let an air bubble or void see the HPFP. This is why I will always prime it with VCDS even after fuel filter changes.

Dan
 

Growler

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so the little roller is free to spin at the end of that spring its attached to? why wouldnt they pin that thing so that it is ALWAYS square to the cam lobe..

and WOW I cannot believe that the lobe is worn away THAT much.. that ridge on the outer edges is INSANE!

is there MORE wear in the center of the cam lobe than at the edges? that woudl support the thought of the roller getting turned off square.
 
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KraftwerkB6

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oilhammer said:
Someone in another thread eluded to the fact that the roller piston could rotate and be riding at right angles to the shaft, and sure enough, I confirmed here that yes it can, there is NOTHING I can see to keep the piston aligned properly with the shaft cams.

And that would explain the strange wear marks I have on this little roller.

Updated original post with more pics.
just saw this thread. Yes the little roller bearing turned 90 on the one that i saw. And so they rolled on eachother for however long opposite of eachother. the little roller actually had a indention in it from rolling so long and destroying itself.
 

bsalbrig

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The roller can only turn at the top or bottom of its stroke so it would have to make its 90deg rotation in the short ammmount of time when it is at either postion. I could see the piston turning slightly and then back during these conditions but not 90deg. That roller looks like it has rolled over some small particles and they have been pressed into it.
 

ziggy55

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Being an owner of a 2010 Golf this has me very concerned. I have to admit that we do have ourselves to blame a little, we did buy a Volkswagen. This is my 6th VW and I vowed after each that this would be my last. I have owned other cars too, but keep going back to VW. Its like taking drugs, your addicted and keep poisioning yourself.

That being the fact does not excuse VW/Bosch from poor design. This failure looks like a combination of poor fuel, poor design and probably faulty pumps due to manufacturing material issues. Maybe they should QC sample their units more, and verify the process of manufatcuring.

Another issue I have is what kind of sloppy filtering system is this. Unit fails and contamination is caused all over the fuel system, whats the point of the filter (good looks). Why not have a water collector also doesn't hurt.

Also if this pump was designed for ideal conditions, shame on the engineers, maybe they should leave the cubicle and have a field trip to the local refinery and follow the fuel delivery right to the station. There is no way any fuel pumped from a station is 100% perfect. There will always be some water, contaminants and foreign trace solvent present. I remember watching them dig up storage tanks form a local station and guess what some of the tanks didn't have any bottoms left.

As I see it we need to start putting pressure on VW immediatly and very aggresivley.

I would alsolike to thank all who are already working on a solution. Maybe in the meantime we can develop some sort of better filtering system that will catch all the contaminants from the pump before a repair will cost you half the price of the car(???). This is starting to sound like the W8 fiasco.
 

oilhammer

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There are just too many to list....
It is NOT the filter. Please, forget about that. The filter setup on these is the exact same as the BRM cars, and they never have any issues.

This is a case of possibly poor metallurgy, undersized roller, or perhaps the fact that the pump piston can mysteriously turn in its bore.

The last part could be remedied with some sort of 'dog' to index the piston at right angles to the shaft so it simply cannot turn. Or make the piston bore a 'D' shape.
 

ziggy55

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Yes I know it is not the filter. I was just pointitng out that what kind of filter design allows the whole fuel system to contaminent with metal based on the failure of the pump.
 

jkp1187

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oilhammer said:
It is NOT the filter. Please, forget about that. The filter setup on these is the exact same as the BRM cars, and they never have any issues.

This is a case of possibly poor metallurgy, undersized roller, or perhaps the fact that the pump piston can mysteriously turn in its bore.

The last part could be remedied with some sort of 'dog' to index the piston at right angles to the shaft so it simply cannot turn. Or make the piston bore a 'D' shape.
I ain't no engineer, but why would one design a pump like this, WITHOUT something to keep the piston from turning? Is there any advantage to it?

It's also interesting to me that Bosch is also the manufacturer (or was the manufacturer,) of the BMW N54 HPFP, which has also had a history of trouble -- though none as spectacular as the failures we've been seeing with VAG's 4-cyl TDI.
 
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