HPFP Story

Note: I have NOT had a HPFP fail on my '09! (knock on wood)

Right before I went into the dealership to look at the '09 models, I took my '06 in for it's 40k service. I saw the mechanic in the service bay and inquired about the '09's, and he told me he had had to replace a fuel system. Naturally, I assumed that the owner had made a mistake, or something to that effect. This was not the case.
Three months later, I trade my '06 in on an '09, not hearing anymore about the issue, but reading about the HPFP failures here on the forum.
Fast-Forward to today:
I take my '09 in for it's 10k, and catch the mechanic in the service bay again.
I ask him about the HPFP issues, and lo and behold, he states that they have had one recently, but only the one previously and this current one.
Well, later on while I wait, I get a visit by a person, who says to come look at the pump before they pitch it. I was excited to get this chance, after following the threads here, especially concerning the bad fuel, rust, etc., claims of other dealerships.
I can tell you this from my close observation of the disassembled pump. There is a design flaw in the piston to cam surface area, that no matter what fuel, additive or anything else you use, will cause catastrophic pump failure. The pump piston simply floats on a single roller that contacts the pump cam. If this roller is turned 90 degrees from parallel to the cam, then the roller AND cam grind each other to bits,right down the middle of each other.
There is no mechanism to keep the piston from rotating in the pump, to prevent this from happening, other than the pressure from the piston spring and the cam to roller contact.
So, if you see any metal at all on top of the fuel filter, get ready, because the damage(s) are already done to the HPFP and the cam.

Sorry I did not take pictures, to protect the innocent. I really, really, wanted to!

I hope this helps anyone, because I know now I am armed and ready if it happens to my '09, which had the tranny recall done already.

Thanks for that information. This should be helpful to those experiencing any HPFP issues.

Interested in finding out why you decided to go with an CBEA? Would like to hear your opinions on the 2 model year differences. Rather than confuse your thread here is a link to a thread with other 06 owners that purchased 09/10

http://forums.tdiclub.com/showthread.php?t=232202

As odd as this sounds, I hope this theory is the real cause of failures, and not bad gas.

If it's a design flaw, we have some hope of remedy. If it's simply random "bad gas" and the part is working as designed, we might never have a real work around.


I would like to see photos though. Doesn't need to be of the pump you saw today - anyone who has gone through a HPFP failure should try to get their hands on the pump for us to see

If it is a design flaw then why aren't all of them eating their internals?

What might it be that is causing only a few to hull?

Let's revisit this thread 3 years from now and see if the % of failures increase with age/miles.

Rod Bearing said:

If it is a design flaw then why aren't all of them eating their internals?

What might it be that is causing only a few to hull?

Click to expand...

As per OP:
"If this roller is turned 90 degrees from parallel to the cam, then the roller AND cam grind each other to bits,right down the middle of each other.
There is no mechanism to keep the piston from rotating in the pump, to prevent this from happening, other than the pressure from the piston spring and the cam to roller contact."

If that is fact, the question now becomes:
"What might it be that is causing only a few pistons to rotate in the pump?"
If that is the question, my answer would be:
probability theory: a few out of thousands will rotate and in doing so create a mess...

If that is fact, the question now becomes:
"What might it be that is causing only a few pistons to rotate in the pump?"
If that is the question, my answer would be:
probability theory: a few out of thousands will rotate and in doing so create a mess...
[/quote]

Turning corners too fast will do this.

SoTxBill said:

Turning corners too fast will do this.

Click to expand...

Oh NO! Then I am doomed!!

Have we heard any reports of "catastrophic" HPFP failures? There's a lot of daylight between "there's metal filings in my fuel system" and "catastrophic pump failure".

Bluegrass said:

So, if you see any metal at all on top of the fuel filter, get ready, because the damage(s) are already done to the HPFP and the cam.

Sorry I did not take pictures, to protect the innocent. I really, really, wanted to!

I hope this helps anyone, because I know now I am armed and ready if it happens to my '09, which had the tranny recall done already.

Click to expand...

Thanks for the info. However, I dunno about this last jump regarding metal in the filter. It really seems like half the people who open their filter housings find metal. This includes at least two filter photos posted here of supposedly "clean" filters that in fact show traces of metal. And so far, none of the cars with metal showing up in their filters have subsequently failed -- at least at this time.

Certainly someone here knows someone who "knows someone" that can get the schematics / diagram of the Bosch HPFP in our cars. I am curious how they are built and designed.
Let's just say our HPFP go bad, does VW or Bosch have a different type to put in instead of the current batch of pumps? What options do we have? I believe there has been one report of a member having TWO HPFP failures. This came from maverick395......
http://forums.tdiclub.com/showthread.php?t=269781
Putting the same style pump back in doesn't really make sense to me if it is a known fact they are poorly designed and there's a good chance it will fail at some point. Perhaps Bosch mass-produced these HPFP's under an extreme timeline in order to meet VW's marketing plan. If so, that could have caused the Bosch QA Team to overlook "mediocre" manufacturing processes and allow sub-par quality pumps to get into our cars.

I wonder if this same pump is/was used in European cars.

This is really good info to have. If any Vendors or VW employees are on the Forum, please offer some insight. It would also be nice to have a Service Adviser from a VW dealer online to shed some light on this potential defect.

Some fuel pump porn:
http://www.youtube.com/watch?v=t4lMJ4lqRuo

(This video is the two-piston variety instead of the single piston unit that the TDI uses)

See also:
http://forums.tdiclub.com/showpost.php?p=2288813&postcount=30

FYI, I think the new Ford 6.7L "scorpion" engine uses the two-piston version of our pump, with each piston feeding an engine half.

and that's a totally different cam arrangement to the previous 3- piston CP1; this had an eccentric on the shaft and a close-fitting sleeve as a follower. Something of a radial swash-plate.

I think the BMW 2.0d (the sequentially turbocharged 4-cylinder that makes 204hp) uses a single-piston variant of the Bosch CP4. Anyone know if it's the same as the CBEA pump? Also, what do the older European 2.0l CR TDIs use for a pump; something different than the CBEA?

EDIT: Bluegrass, here's a high-res pic of the Bosch CP4.1 that's used in the CBEA. Perhaps you can better illustrate what you're seeing as potentially being the problem?


I stole this from Drivbiwire...hope he doesn't mind!

Thanks for the photo! Glad to do it.

Without photoshopping, here is a brief breakdown:

Red Circle: If you look close enough, you can see single roller.

Yellow Area: This the area on the high sides of the cam that gets destroyed during the pump cycle. The roller also loses material in the middle, if it locks up in the bottom of the piston, like the one I saw.

So during the pump cycle, if your piston rotates 90 degrees and gets stuck grinding against one-another both the cam and the piston roller are pumping shiny sparkles throughout your fuel system, until they eventually lock your injectors up. I did inquire if the filter would stop this, got a smile and a nod to the NO. I also asked about the other pumps or other components and realized that was a silly question, as the entire fuel delivery system has been replaced on the two I know about.

Check my gallery for the photo.

Bluegrass, how about a link to your gallery/photo?
Thanks, and great thread, interesting thoughts, certainly worth pursuing IMHO! (getting ready for that dreaded fuel filter checkup/replace, hoping to not see any shiny flakes...)

Sorry! Here is the link:

http://pics.tdiclub.com/showphoto.php?photo=64811&size=big&cat=500&ppuser=43654

So the actual piston (with attached roller follower) is rotating and the pump cam and the roller follower are intersecting perpindicular to each other rather than the inteded parallel intersection, correct? Isn't there a guide of some sort for the piston to keep it aligned

Very interesting info. So what it sounds like is that the "piston" is designed to ride on the approaching cam lobe in one direction, but there is nothing to prevent the piston and spring from rotating within its shaft. If this is true, and if the action of the cam is anything like the cams on the engine valves, then the spring may naturally want to rotate the piston.

Here's a cool video of valves and springs rotating on a cam. The rotating begins about halfway through the video.
http://www.youtube.com/watch?v=nsa6kq-qqIE

Very cool vid!

Bluegrass said:

Thanks for the photo! Glad to do it.

Without photoshopping, here is a brief breakdown:

Red Circle: If you look close enough, you can see single roller.

Yellow Area: This the area on the high sides of the cam that gets destroyed during the pump cycle. The roller also loses material in the middle, if it locks up in the bottom of the piston, like the one I saw.

So during the pump cycle, if your piston rotates 90 degrees and gets stuck grinding against one-another both the cam and the piston roller are pumping shiny sparkles throughout your fuel system, until they eventually lock your injectors up. I did inquire if the filter would stop this, got a smile and a nod to the NO. I also asked about the other pumps or other components and realized that was a silly question, as the entire fuel delivery system has been replaced on the two I know about.

Check my gallery for the photo.

Click to expand...

So, does anyone else smell a smoking gun? Probably not until it kills somebody I guess...... (think Toyota!).

The cat's out the bag VWoA.

It would be a disservice to blame this without concrete proof. Otherwise we'll look like the boy who cried wolf any time we spot something that looks out of place.

So, do we know if there's been a running change in the pump or do the '10 models use the same exact pump as the '09s?

True mysql, very true. But after seeing the pump apart, and looking at all of the components individually and partially reassembled, I saw no other reason.
The spring guide just rests inside the piston, so the piston is allowed to rotate freely. Obviously, this was not Bosche's, or VW's intent, but the design allows it, if the pump cycle does not complete properly.
Maybe they need a stronger spring to maintain higher roller pressure against the cam? I am not the one to determine that at all.

So unlike a hydraulic lifter that has a hardened convex face, the piston in these pumps has a flat face and is not hardened?

Given the design, and assuming what has been claimed is true, I wonder if something similar to valve float (or in this case piston float) at high RPM could increase the likelihood of roller misalignment. Do we have any input on engine RPM leading up to failure?

http://en.wikipedia.org/wiki/Valve_float

The only time the piston roller could rotate would be at the top or bottom of travel, any other time the pressure of the roller on the cam will keep it oriented correctly. If the cam began to wear down on one side though it would then destruct itself.