CR engine HPFP analysis

sjjaskow

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2010 Golf TDI 6M
Dweisel, I think that we should add on just one more 'known' quantity to your list, how soon you can have an HPFP blow up. Has anyone read or remembered one that has happened with less than 1k miles on the vehicle? To me if such an early failure exists it would definitely by manufacturer error.

Where are these pumps made? Is there more than one assembly plant? If all the affected pumps were assembled from date x to date y at plant z, that should tell us something.
 

ziggy55

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2010 Golf TDI
Also we should try to get a hold of a new pump and test the hardness.

I would imagine that for both cam and piston roller to wear they must be made of same hardness or does it look like one is sacrificed before the other.
 

DoctorDawg

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dweisel said:
What we now know about hpfp failures

1) All 09/2010 are subject to possible hpfp failure
For the sake of precision I feel the need to point out that we don't actually "know" this, except in the same sense in which we know, for instance, that everyone on earth is "subject to possible" fragmentation grenade attack by a meth-crazed donkey on roller skates....or in the sense that all diesel engine owners everywhere are subject to possible hpfp failure.

The meaningful question concerns the odds, and we don't yet know the odds. While I increasingly share the opinion that the odds are higher than they should be (i.e., higher than for previous version TDIs), it remains the case that an opinion is not knowledge.

Just trying to maintain the always-useful distinction between what we think and what we know, since the blurring of this distinction is the source of most of the world's problems.
 
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cevans

TDIClub Enthusiast, TDI Parts Ninja Vendor , w/Bus
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Armchair Expert Opinion:

Lubricity. The roller and cam lobe are not lubricated enough and wear through each other. And/or the lubrication on the roller isn't sufficient to allow it to roll at the appropriate speed.

End expert opinion.
 

Growler

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is the area where the fuel comes in contact with teh roller and cam open to any of the high pressure system? or is it a seperate circuit in the return path that lubricates the cam & roller?

if so, what about bypassing that area with the return fuel, and rerouting an oil line up there instead?

just talking outta my @$$ here but its a thought.
 

DoctorDawg

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So we have (at least) three hypotheses (which may not be mutually exclusive):

1. Bad engineering, which can permit the roller to turn with respect to the cam under some (currently unknown, but presumably rare) conditions.
2. Bad metallurgy, employing steel grades which can suffer too much wear too fast under the lubricity/cleanliness conditions of real-world U.S.-of-A. diesel fuel.
3. Or it could even be that #2 can lead to #1...too much wear leads to slop in the cam/roller train which can enable the roller to rotate w/r/t the cam; if the metal particles don't get you first then sooner or later your HPFP will catastrophically grenade.

#1 would, I think, probably result in instantaneous catastrophic grenading of the HPFP, leaving clear signs inside that all hell had suddenly broken loose, whereas #2 will slowly but surely accumulate minute metal particles in the fuel system which will sooner or later take their toll on the engine's ability to run, leaving inside the HPFP only a wear signature such as we see in oilhammer's photos, but no evidence of catastrophic failure.

If Hypotheses #2 or 3 are correct, use of a lubricity enhancer is definitely called for. So given what we (don't) know today, I would argue that use of a lubricity additive (or B5) is a wise thing to do, with or without a recommendation from VW. Unfortunately, if Hypothesis #1 is correct then there's not much we can do; its on VW and Bosch to cowboy up and make it right, either before an inevitably successful class action law suit or after.

One thing I'll say here is that I just can't believe that this new HPFP design wasn't extensively tested with real-world fuel, so its just hard to figger how the heck they didn't see this coming. However I am reminded of the frequency with which I buy a bunch of high-grade bolts and find after I've installed them outdoors that one or two are rusted all to hell while the rest still look shiny new, from which observation I have concluded that the supply chain for various high-grade steels is perhaps thoroughly 'contaminated' with low-grade knock-off steel from A Country Which Need Not Be Named Here (ACWNNBNH). So maybe (just a wild-eyed conspiracy theory) Bosch spec'd and tested the correct steel, and it was all good, but now in production they unknowingly end up making some fraction of pumps from cr@ppy knock-off ACWNNBNHese steel? Low probability, I'll admit, but I'm just so puzzled by the question "How on earth did this get past a company like Bosch?" I mean, this ain't hardly their first rodeo.
 
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saucer

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Coming from the MKV FSI community, this is shockingly familiar :mad:

Anyone involved in FSI forums should know by now that it's crucial to check the thimble style cam follower every 10k miles or so. The funny thing is, everyone brainstorming the problems with our HPFPs believe a roller would be the solution!

Here's an example of what a busted follower looks like on the FSI. Note the hollowed-thimble follower (lower right) and the disintegration of the plunger/spring on the HPFP (center):


And the ultimate effect on the cam lobes:



There are hundreds of threads regarding this issue of golfmkv, myfastgti and the vortex. People have been mailing their shredded followers to VWoA, threatening class action lawsuits, and raising just as much of a stink for over three years now but afaik, VW hasn't even released a TSB.

The issues don't seem to be quite as severe when the follower is finally eaten through as with the TDI though. People have even continued to drive for thousands of miles with little more than fuel cuts and rough idling. Still a mess to fix... I've seen numbers of $6k or more for replacing the cam shaft, pump, etc.

I pulled mine at 35k and the DLC was completely gone with a bit of scoring on the metal beneath, looking a just a bit worse than the one on the left:


The different harnesses of metals did play a role in helping the scenario - but not fixing it. If I remember correctly, 06 and some 07s came with a cam lobe that was too hard (or too soft?) that created a frictional incompatibility. This is also a double edged sword; after the follower is chewed through, the cam lobe is damaged from grinding on the new bits of shrapnel and the plunger from the HPFP. Then once the plunger is eaten through.... boom.

The only "good" thing about the FSI scenario, is this it being a 15 minute/$50 fix. Doens't look so easy or preventable with the TDI. FSI guys have been testing every oil and additive under the sun, and no one has nailed a firm conclusion on lubrication there either.

After seeing this issue in other VWs... instant facepalm.
 
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oilhammer

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outside St Louis, MO
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There are just too many to list....
Guys, please keep the thread relevant. I started this thread because there are plenty of other threads about the odds of this happening or not happening, and as a VW specialist, I feel for the FSI owners, but again, that is not the scope nor purpose of this thread.

Right now I would love to get my hands on a new HPFP and take it apart. I think that the piston roller is too small, and can go off square in the bore. But in order to make it larger, they would have to make the piston cup longer, which would mean the entire upper part of the pump body would need to be extended some. And then it needs to be made so that it cannot turn in its bore.

I looked at my specimen today with a high powered magnifying glass, and it clearly looks like it did indeed spin wonky in the bore and wore some bad spots in the roller in short order.

There is also a lot of scoring on the piston itself.
 

Derrel H Green

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Just Because it's Bosch

DoctorDawg said:
"How on earth did this get past a company like Bosch?" I mean, this ain't hardly their first rodeo.
:)

doesn't mean it is the best or is as clean as it should be as you might believe!

Case in point:
Back in 1979, both my now deceased friend and I had new "L" model VW four door diesels, and
we went together halves on a set of brand new injectors from VW. These were brand new,
not rebuilt, and still sealed in their respective boxes, unopened. $30 each back then.

When he opened each injector body to reset the spring tensions to 2000 pounds firing pressures for
my hotrod turboed 1457 cc engine, he found rust in each one! Rust in brand new Bosch injectors.
Don't get the idea because it's Bosch that it is clean and precision built. It just is not so. :eek:

:D

D
 

Derrel H Green

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Of Course

martytdi said:
Would some biodiesel make the fuel a little more slick?

2010 JSW with DSG
:)

it would Marty. That's why I heard that the editor of PM mazagine was told by VW to take the test
-car he was driving down to Playa del Rey (a Yacht type harbor) and get some biodiesel and
add that to the mix AFTER that car had the works done on it when it's HPFP went South!

Let me put it this way: Biodiesel or any additive that does not harm the DPF
certainly will not hurt anything provide you do not go overboard.

:D

D
 

nicklockard

Torque Dorque
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Arizona
TDI
SOLD 2010 Touareg Tdi w/factory Tow PCKG
D-Cell Mekaneck said:
Maybe you could add a chip detector in the return fuel line?

Magnets on your fuel lines are starting to sound pretty good.;)
:rolleyes:
 
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saucer

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Sorry I got carried away with the FSI info - I thought some might find it interesting :eek:
Here's a huge thread on vortex about the FSI roller solution... maybe someone could get some ideas or PM H2Sport to see how they plan on keeping the roller straight.

As I mentioned though, the FSI HPFP is very easy to access and inspect. Is that not the case here?

I'll be picking up a new TDI in a week or so am getting nervous about this mysterious roller.
 
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cevans

TDIClub Enthusiast, TDI Parts Ninja Vendor , w/Bus
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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.
Thought some more about this:

Based on the picture of the cam lobe, I don't think this is happening. The wear on the cam lobe is very uniform and it appears to be exactly the width of the roller on the piston. If the piston/roller is rotating and hitting the cam at an angle, wouldn't that produce a cam lobe that has more wear in the center, in more of a cup form, than straight even wear across the top?
 

oilhammer

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There are just too many to list....
cevans said:
Thought some more about this:

Based on the picture of the cam lobe, I don't think this is happening. The wear on the cam lobe is very uniform and it appears to be exactly the width of the roller on the piston. If the piston/roller is rotating and hitting the cam at an angle, wouldn't that produce a cam lobe that has more wear in the center, in more of a cup form, than straight even wear across the top?
Yes, you are correct, but if the piston went sideways right before catastrophe, it may not show much wear on the shaft's cam lobes. Remember, these cars go from running fine to not running almost within a mile or so, as least as I understand it.
 

birkie

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saucer said:
Sorry I got carried away with the FSI info - I thought some might find it interesting
I found it interesting. It seems that the only thing the DLC coating is good at in these pumps is wearing away :rolleyes:

As I mentioned though, the FSI HPFP is very easy to access and inspect. Is that not the case here?
I don't think so. The cam/piston is internal to the pump. Generally, the internal components of a diesel injector pump are thought to be of such tight tolerances that they are cannot realistically be inspected or repaired by mere mortals. I'm assuming this is the case here, although from the pics it looks so darn crude and simple in there.

There are shops that specialize in rebuilding pumps (such as DFIS). It would be fascinating to have one of these failed pumps sent to be rebuilt, and hear what they would have to say as well.

Say, I wonder if there are any bosch-certified service centers that have experience with these things. It would be neat to hear what they have to say about them in general. (e.g. do they get a lot of them? Do they all look like this one, failing in generally the same way?)
 
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HeAvYfUeL

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Gatineau,CAN
TDI
2009, Golf Variant, DSG
Is it possible that the damage to the roller is caused by 'hamering' of the HPFP plunger due too a bad functioning of (a) pressure control valve(s) or the injectors that are injecting quickly very small amounts during the powerstroke that causes 'hamering in the Common rail?
My 2c.
 

cevans

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oilhammer said:
Yes, you are correct, but if the piston went sideways right before catastrophe, it may not show much wear on the shaft's cam lobes. Remember, these cars go from running fine to not running almost within a mile or so, as least as I understand it.
Yep, makes sense, would there be some indication of that - e.g. horizontal marks on the roller?

Is the pressure control valve visible in the photos?
 

Nimbus

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Location
New England
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Service Training for 2.0 Liter TDI Common Rail Engine

I've read some questions on this thread that can be anwsered by the following pdf. Not sure how long this will remain on the web, so save a copy.

http://www.dsd.go.th/itrain/km/kboc/2552_Test_Project_WSC40/Automobile/DOC33_IL_40CA/DOC33_IL_40CA_1680_Diesel_Engine_2.0L_TDI_CommonRail_BIN5_UL.pdf

See pages 26 - 41 for fuel system description and a nice overview of the HPFP operation. There are also descriptions of "Effect of Failures" for certain components.

Referring to page 33, I find it difficult to understand why the entire injector system needs to be rebuilt if the HPFP fails at the cam/roller interface. Notice that there are "fine filters" that will prevent metal from entering the high pressure rail. The only thing that should need to be changed is the HPFP ??? Something else in the HPFP needs to fail to require the injectors to be replaced (e.g. exhaust valve, top of pump piston, intake valve, etc).

Also, I think the pump piston is kept from rotating by the interaction of the roller with the cam. The force of the spring pushing on the roller should keep it in the right position as the cam rotates. There is probably a fine "wobble" that occurs, but this should be mitigated by the lubrication of the fuel. If the lubrication is not there and the roller starts to break apart, metal particles will clog the "fine filters" in the HPFP. First symptom would most likely be reduced power and then a complete shutdown due to lack of fuel.
 

manual_tranny

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aja8888 said:
Very nice engine manual. Boy, things have gotten complicated in the last few years.
Another thanks to Nimbus, what a great resource. Makes me want to hold on to my '75 240D. Simple can be good!!
 

truman

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Quote:There is probably a fine "wobble" that occurs, but this should be mitigated by the lubrication of the fuel. If the lubrication is not there and the roller starts to break apart, metal particles will clog the "fine filters" in the HPFP. First symptom would most likely be reduced power and then a complete shutdown due to lack of fuel.

This makes sense to me and would explain why failure is sudden and catastrophic. The followup question would be how and why could a fuel starvation/lubrication condition occur at the cam roller interface?
 

Growler

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maybe the return check valves are opening too soon, and allowing the cam & roller in the pump to run dry.
 

aja8888

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manual_tranny said:
Another thanks to Nimbus, what a great resource. Makes me want to hold on to my '75 240D. Simple can be good!!
Yeah, and I am holding on to my Passat, too. I am a mechanical engineer and after spending a fair bit of time reading that manual, I can see why VW dealer repair shops can have their hands full with the complexity of the system. Plus, their dealing with gassrs 90+% of the time increases the unfamiliarity of the techs with it.
 
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