CR engine HPFP analysis

kjclow · Mar 30, 2012

fireinsyrup said:
kjclow said:

Have you filed with NHTSA?

Not yet, I'm still waiting to hear back from dealer/VW with the official repairs needed on the car. Do the complaints basically get sent to VW?

And I was just thinking warranty for the sake of not having to argue with any dealers on whether the repairs would be covered under VW if it ever happens again. ...There really weren't any warning signs of failure..

Click to expand...

Not having been through this, I'm not sure of the exact path but think that you need to file even if VW covers it all. Helps those of us that may still need the recall.

specsalot · Mar 31, 2012

fireinsyrup said:
So my 2011 Golf TDI recently encountered a failed HPFP, everything is being covered under warranty no questions asked thank goodness.
The car is already paid for, does anyone think extending the warranty is a good idea? I just hit 25000 miles when the pump failed, and I only have the standard warranty (3yrs, 30k miles)
Thoughts?

I haven't seen it in writing, but it's been posted in these forums that VW now covers the HPFP under 5 year / 60,000 mile protection. Extended warranties are a debate lots of posting pro and con. I bought one. Have one on my Jeep that's been very helpful.

Sorry to hear - Just searched and saw this is an evolving situation for you. Consider starting a thread to inform the community. There are many here who follow failures, especially posters to this thread. Any details you can provide regarding your evolution will be helpful. Many posters have been through the failure process here. Lots of good advice for the asking. Thanks in advance.

specsalot · Mar 31, 2012

MajorDJQ said:
(originally posted in the Water fuel separator thread)

According to the diagrams in the self-study guide, the filter screen is between the Aux pump and the HPFP. How is it going to stop particles from getting to the rest of the fuel system? Just as particles precipitate to the bottom of the fuel filter canister, I would bet it also collects on the bottom of the fuel tank. If it gets sucked up by the lift pump, the fuel filter should stop them. But is the filter screen a finer filter than the regular fuel filter?

I would have to think that if the HPFP is shedding metal, some of it will go into the rail, and some of it will go out the low side return. Since so little fuel is injected as compared to what heads back to the tank, maybe the injectors don't see to much of the particles.

I think your last paragraph is a fair explanation why not much of the wear material that seems to be inside our HPFP's makes it into the HP section of the pump. If you look at the flow internal to the HPFP casing most of the supplied fuel short circuits directly to the return passage through the Overflow Valve.

eddif posted a great pic (inserted below) showing the flow paths.

Fuel enters the LP casing through the small hole located at ~ 9 o'clock with the red wire in it. The only passage out of the LP casing is the other hole located at ~ 12 o'clock. This is the pathway that leads to the fuel metering valve. So basically (except for combustion fuel flow) the LP portion of the HPFP is a dead end as far as fuel flow goes. There are small fuel flows through the bearings that communicate with the return side. One of them is shown by the green wire.

So when you think about what is actually taking place in the HPFP casing, it's not surprising that wear materials probably builds up there at relatively high levels before material gets push out in recirculation returns, or enters the HP pump section.

Niner · Apr 1, 2012

specsalot said:
My Jeep has a CP3. I really wish my TDI a two piston equivalent CP3 installed as well.

And by doing just that, you half the duty cycle of each piston, and can run the pump at half the crank pulley speed too. A win win, less rpm on the pump and less stress on all parts involved, including number of cycles for Mean Time Between Failure.

Niner · Apr 1, 2012

Niner said:
I had to go public, you guys were hitting it so hard. new link.
http://www.youtube.com/watch?v=j-EbvKDzWMo

Very interesting... I got 4 hits on this video from the Fatherland last week, and this is not an April Fools post, it's serious!

At least someone in Germany has watched it, hopefully with a good English Translator. I mean if Vw needs a good German to English translator for the NHTSA, then it follows that the "B" side needs a good translator too.

Niner · Apr 1, 2012

Bosch could make the whole jug, cylinder and head assembly out of steel parts, and make it with bolt on jugs for the whole item, bolting into the crankcase.
If they did that, the pump would be completely rebuildable with just a top end swap, without touching the lower end if the cam is still worn within specifications. Heck, put some fins on the head and cylinder for cooling.

specsalot · Apr 1, 2012

Yep - We should have all been so lucky. At minimum they ought to open up the pump by making replacement spares available, and specifying useful preventative maintenance and inspection regimes to identify and remediate failures before they become total failures. This absolutely can be done if Bosch / VW would allow it.

Plus 3 Golfer · Apr 2, 2012

specsalot said:
Yep - We should have all been so lucky. At minimum they ought to open up the pump by making replacement spares available, and specifying useful preventative maintenance and inspection regimes to identify and remediate failures before they become total failures. This absolutely can be done if Bosch / VW would allow it.

This sounds good and works in an industrial / commercial setting where there are maint. techs that can inspect / monitor equipment periodically. This is not a "fix" for the general consumer because "useful preventative maintenance" would likely need to be done too frequently and cost too much.

So, I'm on my way across country. What do I do: carry tools and spare parts, stop every fillup, 1k or 2k miles and inspect / replace. Even if inspection / replacement were every 3k miles (based on what we've seen anything more is likely not much different than not inspecting), the cost for such at the dealership / guru would likely make owing a TDI not worth it. And besides, what if we pump some bad fuel in.

pknopp · Apr 2, 2012

specsalot said:
Yep - We should have all been so lucky. At minimum they ought to open up the pump by making replacement spares available, and specifying useful preventative maintenance and inspection regimes to identify and remediate failures before they become total failures. This absolutely can be done if Bosch / VW would allow it.

If rebuilt units are being used (as noted in the main HPFP thread) then these replacement parts are made. Indeed, they should be made available.

THen again, Dweisel believes it's the barrels causing the problem. If so, you can't just replace them.

specsalot · Apr 2, 2012

You are both correct. This forum is for enthusiasts who typically believe QA begins at home. Most of us have no problems wrenching if required. I sometimes tend to lose sight of this reality.

I have close to 30 years in engineering O&M with almost 1/2 of that specific to diesel engineering. This stuff isn't supersition and magic. My focus on this section is figuring out the core issues from the perspective of keeping my TDI running for my expected ownership interval.

One practical approach to HPFP longevity would be to identify and remediate the early stages of HPFP failure. This narrows the repair to just the HPFP. If interchangeable parts became available, remediation would be a flush and replace process. LP bore issues could be monitored with pump replacement dictated by bore issues.

There are a lot of factors in play associated with these failures. If you look at Bosch's accomplishments, it would seem that solving these failure issues would be relatively simple. VW, Audi, and newest generation of Ford truck diesels all use CP 4.X pumps. If the Ford units do not begin to approach the 1% failure rate than the issue here probably rest with the balance of VW's fuel system. VW has redesigned the MY2012 Passats fuel systems as compared to the Golf / JSW. I would be willing to bet that Passat CR pressure is being lowered as part of the redesign.

A real fix would be to have an HPFP that doesn't experience catastrophic failure in ~ 1% of installed units. While Bosch and VW maintain that this is purely a fuel quality issue, the annocdotal evidenence suggests otherwise.

VW has already hedged it's bets and broken ranks with Bosch in using Delphi units (HPFP's, injectors, control systems) on their 3 cylinder TDI Polo's in Europe. So it suggests a rift is what should be a very strategic relationship for both companies. Bosch holds a lot of liability in this situation unless they can prove the issue is due to the balance of VW's fuel system. Problem with that is that Bosch probably makes most of the other components as well. I don't think Bosch is going to be doing VW any favors on interchangable parts. Especially if it really is a parts issue. Making parts available could be framed legally as an admission that this is a parts issue.

pknopp · Apr 2, 2012

Making parts available could be framed legally as an admission that this is a parts issue.

Not that they don't think this way, they likely do. I've always been able to buy a carb rebuild kit. That doesn't mean there was something wrong with the design nor does anyone think that.

specsalot · Apr 2, 2012

True - You are right - I don't want to debate my choice of language, or the legal constructs. I'm not a lawyer, but we all know that product liability lawsuits are a great niche market.

Comparisons fall short between buying maintenance parts and parts to remediate catastrophic failures. We all know:

HPFP's failure costs $6 - $8k to fix if fully blown.
Up until the NHTSA engineering evaluation the default response to failures was to place them on the owner's account due to the owners use of contaminated fuel.
VW recommended filing property insurance claims to cover the costs of repairs.

The material costs of this issue make it much closer to being a product liability issue that a low cost carb rebuild. An full blow HPFP failure is equivalent to driving your car into a tree.

Let's imagine that in 2 or 3 years HPFP failures in the fleet begin to approach 3% due to operating hours on this installed base of pumps. At this point all owners will see a significant impact to their resale value because no one will want to own one.

Diesel injection manufacturers have already hedged their positions by endorsing common position statements with respect to both ULSD and Bio-Diesel. The local Bosch injection shop freely acknowledges a ramp up in business coincident with the introduction of ULSD.

I don't think these failures are 100% fuel related. I've decided I can live with the risks I carry and will have a plan inplace to follow once I get beyond 5/60.

We all wish we weren't here, but this is where we are.

pknopp · Apr 2, 2012

specsalot said:
True - You are right - I don't want to debate my choice of language, or the legal constructs. I'm not a lawyer, but we all know that product liability lawsuits are a great niche market.

No, your wording was correct. Your point is correct. I'd be happy if the rebuild parts were made available, not claim that it was proof that it was flawed.

I don't think these failures are 100% fuel related. I've decided I can live with the risks I carry and will have a plan inplace to follow once I get beyond 5/60.

We all wish we weren't here, but this is where we are.

Of course not all are fuel related. Or at the very least, not to where it would make it understandable. All parts fail eventually. I understand it will fail sooner or later. It's why I would like to drop in a new cup and roller at 120,000 if it's determined that is the failures source.

Anyway, there will be a determination before I'm out of waranty.

specsalot · Apr 2, 2012

What bothers me most about the issues reported with HFPF's is that there really isn't much of an observable pattern to them. With the exception of a gross miss fuel, issues appear to be cumulative and slow to build. If it weren't for the anti-tamper plastic cap, it would be a simple task to unbolt the HP section and inspect the cam follower / roller assembly. I'll bet that no one experiences failure until the roller carrier has significant coating damage.

Had the flashing glow plug and limp mode on the way home from work tonight. Still working to sort it out before taking to the shop for the "expert diagnosis" later in the week.

Niner · Apr 2, 2012

You can pull the pressure sensor and take a peek inside for debris too, with a couple of torx screws, while the HPFP is still mounted, without it being considered tampering. Vw does it all the time, usually after they've opened up the fuel filter cover and discovered shiny metal in there first.

specsalot · Apr 3, 2012

Yep - I will be proceding methodically a few hours at a time after work hours this week. Glow plug flashing didn't pick back up when I restarted to put the car in the garage last night. Instincts say something got "stuck" yesterday evening leaving work.

coldspot · Apr 7, 2012

Most interesting reading, no problems with mine so far but I will be buying the extended warranty in the next week or so which will get me to 140,000 km b to b. I certainly hope we can get an adapter built in the next while and I really hope we can see whether or not the new Delphi pump can be fitted and programmed. My son in law who is a former gm dealer mechanic has advised that there have been complete fuel system replacements in the late model diesel trucks. Not every time a pump fails but often enought that gm knows about it.
Moral of this story is that almost every manufacturer is having problems- just not quite so spectacular as our TDI's
Gord

Niner · Apr 7, 2012

coldspot said:
Most interesting reading, no problems with mine so far but I will be buying the extended warranty in the next week or so which will get me to 140,000 km b to b. I certainly hope we can get an adapter built in the next while and I really hope we can see whether or not the new Delphi pump can be fitted and programmed. My son in law who is a former gm dealer mechanic has advised that there have been complete fuel system replacements in the late model diesel trucks. Not every time a pump fails but often enought that gm knows about it.
Moral of this story is that almost every manufacturer is having problems- just not quite so spectacular as our TDI's
Gord

They are having problems if they are running the same family of pump, the Bosch CP-4.1 or if a v6 o v8 the CP4.2 . It's a Bosch problem, not a truck badge brand problem.

Cooper · Apr 8, 2012

We had the furnaces and A/C units at our house replaced last week. I was talking diesels with the guys.

One of the guys had a 4-cylinder Mitsubishi work truck. They were all saying that it just may be the slowest vehicle on the road.

The foreman of the crew said that all manufacturers are having fuel pump issues.

coldspot · Apr 8, 2012

Yes it does appear to be a Bosch problem. The other diesels that use Bosch pumps appear to have a lower failure rate. Ford hpfp is considered problematic now according to some of the posts in their forums while the GM Hpfp is not considered problematic in their world.
There is an argument that the truck diesels have better fuel filtration and water seperation that has Been repeated in this thread. The Ford Hpfp failure rate is I think noticeable now while the GM Hpfp failure rate is not noticeable in the forums. My son in law who watches these things because he used to work on them says the GM hpfp failure rate is higher than reported and just as destructive as the Jetta Hpfp failures.
I guess I was hoping to add to this thread that the differences in Hpfp pump design between the trucks and Jettas may be resulting in a lower failure rate. The purported better filtration and water seperation may be helping as well. However, every version of this pump is failing no matter who installs it.
Just summing up some thoughts and hopefully contributing a bit.
Gord

piper109 · Apr 9, 2012

Niner said:
Very interesting... I got 4 hits on this video from the Fatherland last week, and this is not an April Fools post, it's serious! At least someone in Germany has watched it, hopefully with a good English Translator. I mean if Vw needs a good German to English translator for the NHTSA, then it follows that the "B" side needs a good translator too.

The way you spelled Bosch, "Borcht", you may have hits from people looking for info on a tasty Ukrainian soup

eddif · Apr 10, 2012

Niner said:
You can pull the pressure sensor and take a peek inside for debris too, with a couple of torx screws, while the HPFP is still mounted, without it being considered tampering. Vw does it all the time, usually after they've opened up the fuel filter cover and discovered shiny metal in there first.

coldspot said:
Most interesting reading, no problems with mine so far but I will be buying the extended warranty in the next week or so which will get me to 140,000 km b to b. I certainly hope we can get an adapter built in the next while and I really hope we can see whether or not the new Delphi pump can be fitted and programmed. My son in law who is a former gm dealer mechanic has advised that there have been complete fuel system replacements in the late model diesel trucks. Not every time a pump fails but often enought that gm knows about it.
Moral of this story is that almost every manufacturer is having problems- just not quite so spectacular as our TDI's
Gord

Everyone should read:
http://www.synlube.com/oilfilters.htm

Just note that VW was one of the last manufacturers to use modern filtration media (note year). They used screens with most aircooled engines. Also, note that we are one of the last group of folks still replacing a filter that is not contained in a throwaway container. Not that it is not possible to use the VW set up, but that it does possibly leave some possible contaminates (at filter change experience) that other methods remove. This possible transfer of wear particles is one reason I suggest you do not do too many inspections (particles disturbed do not have filter media to remove them before the next stage). This might not matter if all the wear material went through the filter, but in the case of the HPFP.... the system is more like a by-pass system than a full flow system. I know some would not see it that way, but the thermal by-pass and complicated system, IMHO, have some strange flow patterns when it comes to filtration. Wear materials are generated after the filter and contaminate system parts before being filtered again (HP piston for Rail...is an example).

eddif

specsalot · Apr 10, 2012

eddif - You make a great point here regarding the tendency of fuel system to operate a bit like a 'bypass' system during the thermal cycle of the fuel heating valve. Cold start ups in cold weather will tend to have more of what is in the HPFP recirculated back to the clean side of the fuel filter. People who do lots of short drives may see more in the clean side of their fuel filters than folks who typically commute longer distances. I don't think anyone sees lots of metal unless there are issues with the HPFP. That said, I saw a lot of metal in the failed pump from dweisel despite the fact that the pump internals looked pristine.

2micron's fuel flow measurements from a thread on water fuel separators suggests that the entire fuel tank volume passes through the fuel filter approximately every 20 minutes. Most of this recirculation is a direct return to the fuel tank. Return to the fuel filter clean side only occurs when the fuel supply temperature is below the temperature that opens the fuel heating valve.

Regarding my own flashing glow plug / limp mode issue. 740GLE called it as a VNT issue. I've put over 600 miles on the car since then and this problem has not been duplicated. I had the car in the dealers today. They really had no useful explanation except that they clarified my situation to be an over boost rather than an under boost issue. They ran diagnostics, test drove and ultimately cleared the fault code. Time will tell.

kjclow · Apr 10, 2012

specsalot said:
eddif - You make a great point here regarding the tendency of fuel system to operate a bit like a 'bypass' system during the thermal cycle of the fuel heating valve. Cold start ups in cold weather will tend to have more of what is in the HPFP recirculated back to the clean side of the fuel filter. People who do lots of short drives may see more in their fuel filters than folks who typically commute longer distances.

2micron's fuel flow measurements from the earlier thread on water fuel separators suggests that the entire fuel tank contents pass through the fuel filter approximately every 20 minutes. Most of this recirculation is a direct return to the fuel tank. Return to the fuel filter clean side only occur when the fuel supply temperature is below the temperature that opens the fuel heating valve path to the fuel tank.

With that thought process, would it not make sense to put a filter in the tank or at least on the pickup line from the tank? It might not save the hpfp from itself but at least would offer some protection from the gunk that is being returned directly to the tank while by-passing the filter. It would also not have to be put on a high pressure line and perhaps less visable to the VW shop where they may look at other filtration systems and cancel the remaining warranty.

specsalot · Apr 10, 2012

There is a screen element in the fuel tank on the suction side of the lift pump. This is what it looks like:

This one shows some damage, but this may have occurred in shipment when dweisel sent me the HPFP I'm reviewing. It's not real robust. The filter material is fabric mesh not metal mesh. The challenge with adding filtration to the tank return is that as it plugged up, it would tend to elevate the pressures in the transfer system. Two things would happen at once if this occurred:

1. The overall return flow would decrease. If recirc flow plays a part in removing heat from the HPFP, that this sets up for an HPFP overheat situation.

2. Elevating the supply pressure to the HPFP will make it more difficult for the Fuel Metering Valve to work correctly. This potentially sets the stage for an inability to control CR pressure. The Fuel Metering Valve alters the "effective stroke" of the HPFP by throttling the fuel inflow. This in combination with the Fuel Pressure Regulator helps to control CR pressure.

This is why supplemental filtration is a challenge with this fuel system as it is currently designed. The literature and other posters here have commented that the overall design of this system is such that it minimizes the parasitic loss of the HPFP on engine output.

specsalot · Apr 10, 2012

We all know there is a fuel screen on the inlet to the HPFP. I'm hoping it does something in the mix besides just protecting against failure of the Aux Fuel Pump. It's metallic and very fine mesh compared to the size of wear materials shown in pictures.

I wonder how much of the HPFP gets re-deposited there before failure? No one gets to inspect failed components any more. But perhaps some of you were able to do in 2009 or 2010.

dweisel · Apr 10, 2012

specsalot said:
We all know there is a fuel screen on the inlet to the HPFP. I'm hoping it does something in the mix besides just protecting against failure of the Aux Fuel Pump. It's metallic and very fine mesh compared to the size of wear materials shown in pictures.

I wonder how much of the HPFP gets re-deposited there before failure? No one gets to inspect failed components any more. But perhaps some of you were able to do in 2009 or 2010.

As far as the screen in the fuel temp sensor before the hpfp. I've never seen one that had any metal particles on the screen. That would lead one to believe that wear material DO NOT flow in a complete loop through the fuel system.

specsalot · Apr 10, 2012

Thats kind of what I was thinking. This suggests that by the time metal starts making it out of the pump that things are probably pretty bad inside. When you look at the flow pathway's in the pump, there really isn't a lot of circulation through the pump itself. One hole dumps fuel into the LP cavity. Another hole basically delivers fuel out to the Fuel Metering valve.

The predominant recirc takes place directly with the incoming fuel pushing past the overflow valve. I believe this pump is basically a dead end for swarf that goes round and round until there is lots of it. I'm sure there's a lot of fuel movement within the LP body, but nothing I can really see that would tend to move it out of the body.

The only other recirculation paths involve passage through the CR rail and either back through the Pressure Regulator or through injector leak off. I want to believe that any contamination making it to the CR rail would pose a major threat to the injection equipment. My conclusion is that very little contamination gets out of the pump via the HP side.

740GLE · Apr 11, 2012

So what's peoples thought of a nice long high flow pull at say 3-4K for a few miles to flush out the HPFP? more harm than good?

Westro · Apr 11, 2012

So what's peoples thought of a nice long high flow pull at say 3-4K for a few miles to flush out the HPFP? more harm than good?

Not sure I follow you. You believe that sustained RPMs of 3000 to 4000 will help flush out the HPFP? I would think the opposite, idle would cause the most fuel to be returned in the system, not high load.

CR engine HPFP analysis

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