After my wife's hpfp failure back in Sept of 2009 I started to try and determine why her hpfp failed. Since then other hpfps have failed across the country. The main reason at this time seems to be low or lack of lubricity in some fuels. So,some fuels make some hpfps fail.Through hours and hours of online forum discussions,emails,phone calls and picking anyone's brain that even knew one thing about diesel engines I and others came up with the conclusion that the roller/cam was failing. Any of the failed pumps that anyone took apart showed a failure in the roller/cam. I myself had disassembled a couple of failed hpfps. The cam/roller seemed to be the culprit in the failures. Lack of lubrication at the cam/roller was causing the pumps to fail sending metal particles throughout the entire fuel system. I thought we had it after tons and tons of discussions. There was one nagging thing that always bothered me. Some people had a few metal particles on their fuel filters when they did a fuel filter change,but seemed to suffer no ill effects. Their hpfp's were fine. Still running as good as ever. So where were these fine metal particles coming from? Finally in November of 2010 while driving to a local coffee shop it hit me. Its the aluminum bore! The cam/roller failure as previously thought to be the main component failing was the result of and not the cause of the pump failing. These first tiny particles are made in the aluminum bore of the hpfp. In this aluminum bore there is a steel piston cup that holds the roller. Without sufficient lubrication this steel piston cup wears the aluminum bore at an extremely accelerated rate. Once this piston cup starts to make aluminum particles these particles can become trapped between the roller and roller holder. The particles then start to scar the roller and roller holder,making even more metal particles. If enough particles become trapped between the roller and holder the roller can seize up. At that point the seized roller will start to damage the cam. Cam and roller now make more metal particles at a very rapid rate. Even though the cam and roller are failing or failed the hpfp can still make adequate fuel pressure. The stroke of the high pressure part of the pump is unchanged until the cam and roller catasprophically fail. This is when the engine will go into limp mode or quit entirely.
So, in summation its not the roller/cam that are the precipitators of the hpfp failing. It is the steel piston cup accelerated wear on the aluminum bore because of lack of lubrication.
I would stongly advise all CR tdi owners to take steps to insure the fuel they use has sufficient lubricity. Since there are no practical ways to test each fuel up for the fuels lubricity specs, I would suggest that B2 to B5 biodiesel be used along with a lubricity additive. Do whatever you feel comfortable with. I myself add 1 quart of B100,plus Stanadyne Lubricity Forumula to each fuel up on both our 09 tdi's. Lubricity is critical in the new CR hpfp.
I'll up date this thread with pictures or info others may suggest.
dweisel
LUBRICITY,LUBRICITY,LUBRICITY!
Below pics:
Steel piston cup with roller. Note severe wear to piston cup and roller on the right.
hpfp cam. Note severe wear on the uppered pictured cam.
By the time fuel gets past the fuel filter it HAS to be ALMOST perfectly clean. Fuel system components on the clean side of the fuel filter can be subject to damage or wear if fuel has any contaminates.A diesel fuel system HAS to be pristine with NO CONTAMINATES.A sacrificial component would add contamination to the fuel system. There has to be minimal wear on the hpfp components over the life of the fuel pump. Therefore there can be no sacrificial parts. The case of he hpfp is cast aluminum. The particles that people find when doing fuel filter changes ARE aluminum. This can be checked by using a magnet. These initial particles can not be picked up with a magnet. ANY metal particles found that can be picked up with a magnet would have to come from the piston cup,roller or cam. Once ferrous metals are found there is serious internal damage to the hpfp.
I'm currently working on a way to inspect the roller/cam and piston cup of the hpfp without removing it from the engine. ANY wear on these components would indicate a problem.
dweisel
Below pic: shows the aluminum bore of the hpfp. This bore is where the high pressure parts of the hpfp mount. The steel piston cup runs in this bore.
Is it possible that the HPFP itself is being sabotaged by in-tank lift pump not supplying adequate fuel pressure? I ask because Dodge went through a round of issues similiar to this a few years ago. The lift pump would die, but not entirely. So the truck would still run with the weak lift pump, allowing the injection pump to eat itself alive until total failure set in and an expensive injection pump needed to be replaced. I've done a lot of lurking on here and a few other sites and the fuel pump failure scenario is scary, considering the costs involved. But I am wondering if any test is being done the in-tank pumps upon removal? If the entire fuel system is being replaced (as seems to the common "fix") because of contamination, maybe the in-tank pumps are not up to spec. Do we know if the in-tank pumps get bench tested prior to being discarded? Is there a standard fuel pressure spec for the in-tank pump and is could a simple fuel pressure test between the in-tank pump and the HPFP be utilized to check this pressure?
I'm a newb with respect to the TDI, so I apologize if this has been suggested before.
I am very interested in this as it is the sole reason I am an hesitating on buy a NEW Jetta TDI. I don't like the idea of buying a ticking time bomb. I love my diesel truck and want to add a diesel powered car to the fleet.
Dweisel have you measured the bore yet on a defective pump? I'm curious to see how far out of spec it is. And where it's wearing, I'm sure there will be a trend to either a certain side or up higher in the bore or maybe lower.
You have been involved with the CR much more than most. You have supplied information that will lead to solving the problem.
I am a tag along on the CR problems. Most of my involvement has been in the PD cam failure area.
I got involved with the CR mostly through listening to dweisel. Since he had a failure on one of his CRs he has a personal interest. I do not own a CR but will help if I can. I tend to make a list of all the problems and work on those I see as reasonable to fix. Since I do not own a CR theories are about all I can offer. Right now there are about 10 areas that need to be addressed. I will come back and see how things are going.
Dweisel have you measured the bore yet on a defective pump? I'm curious to see how far out of spec it is. And where it's wearing, I'm sure there will be a trend to either a certain side or up higher in the bore or maybe lower.
The problem isn't where thr bore is wearing,but that its wearing at all. I'm sure any pump will wear over time and produce TRACE metals. The type of wear you have i failed pumps happens very fast. The hpfp that have a few metal particles show on the fuel filter top have some wear in the aluminum bore. It MAY or MAY NOT affect the long term service life of the hpfp. That we don't know yet as not enough time has elasped.
One thing I need to ask the machinist next time I talk to him is: What method does he feel will have the LEAST chance to make wear metals if used in th hpfp bore ?
Nicasil coating or silicon impregnated bronze. Whichever ''wears'' better shold be the choice for the piston cup bore fix.
When I changed my wife's 09 fuel filter at 20k it showed a few metal particles. If it continues to show addition metal particles at fuel filter checks or changes, I'll probably get curious enough to pull the high pressure part of the pump and do a piston cup,roller/cam inspection. If any of these parts show scratching it would indicate a potential future problem.
Is it possible that the HPFP itself is being sabotaged by in-tank lift pump not supplying adequate fuel pressure? I ask because Dodge went through a round of issues similiar to this a few years ago. The lift pump would die, but not entirely. So the truck would still run with the weak lift pump, allowing the injection pump to eat itself alive until total failure set in and an expensive injection pump needed to be replaced. I've done a lot of lurking on here and a few other sites and the fuel pump failure scenario is scary, considering the costs involved. But I am wondering if any test is being done the in-tank pumps upon removal? If the entire fuel system is being replaced (as seems to the common "fix") because of contamination, maybe the in-tank pumps are not up to spec. Do we know if the in-tank pumps get bench tested prior to being discarded? Is there a standard fuel pressure spec for the in-tank pump and is could a simple fuel pressure test between the in-tank pump and the HPFP be utilized to check this pressure?
I'm a newb with respect to the TDI, so I apologize if this has been suggested before.
I am very interested in this as it is the sole reason I am an hesitating on buy a NEW Jetta TDI. I don't like the idea of buying a ticking time bomb. I love my diesel truck and want to add a diesel powered car to the fleet.
The in-tank pump merely pushes fuel from the fuel tank through the fuel filter. There is a second elec. pump (boost pump) that actually pumps the fuel TO and THROUGH the hpfp. TO being supply fuel to the high pressure side and THROUGH being through the low pressure lube side of the hpfp. The boost pump also pushes this excess lube fuel back to the fuel tank along with unused return fuel. In-tank and boost punp failures have been very few. On two failed hpfp fuel systems I have both in-tank and boost pumps worked fine even after pumping failed hpfp metal contaminates.
As far as purchasing a new tdi..........go for it! hpfp failure numbers are low. Use a lubricity additive and 2 to 5% bio diesel and the hpfp should function as designed. I feel its just SOME of the fuel making SOME of the pumps fail.
You have been involved with the CR much more than most. You have supplied information that will lead to solving the problem.
I am a tag along on the CR problems. Most of my involvement has been in the PD cam failure area.
I got involved with the CR mostly through listening to dweisel. Since he had a failure on one of his CRs he has a personal interest. I do not own a CR but will help if I can. I tend to make a list of all the problems and work on those I see as reasonable to fix. Since I do not own a CR theories are about all I can offer. Right now there are about 10 areas that need to be addressed. I will come back and see how things are going.
eddif, ''tag a longs'' welcome. We need any ideas out there. Sometimes even the most off topic will send you in an entirely different direction. Sometimes this may be the exact direction that is needed.
One thing you enjoy is a good challenge. Thats what life is all about. Without adversity and challenges, life has no meaning. Keep seeking the answers to the problem. Thats where the satisfactions in life are.
Don't forget to throw in a little lubricity.
Sincerely,
dweisel
The problem isn't where thr bore is wearing,but that its wearing at all. I'm sure any pump will wear over time and produce TRACE metals. The type of wear you have i failed pumps happens very fast. The hpfp that have a few metal particles show on the fuel filter top have some wear in the aluminum bore. It MAY or MAY NOT affect the long term service life of the hpfp. That we don't know yet as not enough time has elasped.
One thing I need to ask the machinist next time I talk to him is: What method does he feel will have the LEAST chance to make wear metals if used in th hpfp bore ?
Nicasil coating or silicon impregnated bronze. Whichever ''wears'' better shold be the choice for the piston cup bore fix.
I can except that the piston bore is wearing at an excelerated rate. But have you measured the bore of a defective pump? It's easy to say the bore is wearing but not so easy to say how much it has worn, looks can be diseaving.
Let's see how true these bores are and in what orientation they are wearing.
I don't totally agree that biodiesel will be a save all. Especially since I don't know the effects it has on Al I do believe that there is a wear issue and that an additive may help. The main problem I see is the disimaliar metals. As I'm sure you know disimaliar metals tend to corrode/gauld like mad.
I think that if you could sleeve the bore of the piston cup with the same material as the piston is made of, instead of trying to use a coating that will wear off, you would significantly drop the wear of the bore, if that is in fact the issue.
I can except that the piston bore is wearing at an excelerated rate. But have you measured the bore of a defective pump? It's easy to say the bore is wearing but not so easy to say how much it has worn, looks can be diseaving.
Let's see how true these bores are and in what orientation they are wearing.
I don't totally agree that biodiesel will be a save all. Especially since I don't know the effects it has on Al I do believe that there is a wear issue and that an additive may help. The main problem I see is the disimaliar metals. As I'm sure you know disimaliar metals tend to corrode/gauld like mad.
I think that if you could sleeve the bore of the piston cup with the same material as the piston is made of, instead of trying to use a coating that will wear off, you would significantly drop the wear of the bore, if that is in fact the issue.
The top 1/4 nch of the bore even on a failed pump will still be to factory spec a the piston cup stroke does not travel in the top 1/4 inch. I think the amount of wear is irrelevant NO wear must take place. This fuel system MUST remain free of ALL contaminates. Trace metal wear would be acceptable,but thats not going to be in a quantity that will eventually cause the roller to fail.
My stance on the use of bio diesel and lubricity additive is simple. Reduce the friction between the steel piston cup and aluminum bore and thereby reduce the wear of the aluminum bore. Yes, it may or may not save all hphps from failing,but its my feeling that it will greatly reduce the chances of a failure. These failures are precipitated totally due to lack of lubrication between the steel piston cup and aluminum bore.
The piston cup is a coated steel. From what I understand it would not be a good idea to use a steel sleeve. It may or may not be possible to nicasil coat both the aluminum bore and the steel piston cup. Thats another question I need to ask the machinist.
I'll try to get someone to mic the bores of the failed pumps I have.
dweisel
We use Al sleeves on GE 7FDL engines for crosshead guides. Basically the same as the piston bore of the hpfp, except these are for the cam followers, intake, fuel, and exhaust. But these are all lubricated with engine oil. The fuel pushrod is lubricated with fuel untill it hits and Umbrella Nut that is the adjuster for fuel timing, then the fuel flows into a return that goes back to the tank. My point being is there is very little between the fuel side and engine oil side, and all lubrication for the roller cup is supplied by oil, not fuel, much more lubricity there. They used to use steel but have changed to Al in the past 10 years or so. I don't know if any of that helps but it just hit me and I thought I would share.
We use Al sleeves on GE 7FDL engines for crosshead guides. Basically the same as the piston bore of the hpfp, except these are for the cam followers, intake, fuel, and exhaust. But these are all lubricated with engine oil. The fuel pushrod is lubricated with fuel untill it hits and Umbrella Nut that is the adjuster for fuel timing, then the fuel flows into a return that goes back to the tank. My point being is there is very little between the fuel side and engine oil side, and all lubrication for the roller cup is supplied by oil, not fuel, much more lubricity there. They used to use steel but have changed to Al in the past 10 years or so. I don't know if any of that helps but it just hit me and I thought I would share.
An oil lubed fuel pump would be better no doubt. eddif is the man to talk to about the possibility of changing the existing hpfp over to an oil lubed pump. Thats one reason I have been providing eddif with pics of the fuel flow/passages of the hpfp. The hpfp is pretty complex,but who knows................maybe it could be done.
I'll just keep working towards some type of solution in the bore.
To DCELL,, I don't agree with you about using similar metals in the HPFP.. This will definitely cause a wear problem.. as we all know, stainless on stainless will gall.. that's why bronze bushings are made for steel shafts. Materials of the same hardness will wear excessively. I agree that a treatment on the aluminum bore, or using a high silicone aluminum alloy may be the fix for this.
The problem here is friction, and discussing what may help reduce friction wear.
As far as I'm concerned any metal to metal contact will cause wear. The piston and cylinder should never actually come in contact with each other, that's why fuel is supplied to lubricate. Oil film is the cushion between these metals. But when that fuel oil film is lacking LUBRICITY or just lacking all together your going to wear. Have two metals that are of the same or similiar hardness will in my opinion reduce the wear metal produced, rather than the softer aluminum bore. The lack of lubrication is what is wearing the softer metal, when that metal wears it sticks to the piston and roller leading to failure.
As far as bushings, they are there to maintain a renewable wear surface and can be self lubricating. More or less are a sacrificial. You certainitly wouldn't want a bronze/brass bore. While it may be more slippery but would at least in my opinion wouldnt last long. You can have the bore to slippery, where you wont be able to maintain that oil film.
A coating may be the solution, I just don't know how long it would last. That's why I suggested sleeving the bore.
The deciding factor on whether the fix is a sleeve OR a coating in the bore, is which material will wear and release the LEAST amount of wear material.
I visited the machine shop on 12/25/10 and spoke with the expert machinist again. Its his feeling that using a nicasil coating would be best in this particular application. I trust his judgement on this as there are only 4 or 5 people in the US that have this guys expertise in custom engine machinine work. He is doing some engine work now for a Nascar Team.
I ask him about taking some measrements on the piston bore and piston cup to determine the specs. He said it would take a few hours to do as he has to heat everything up to 74 degree's to take accurate measurements. He uses an instrument that can be thrown off just from the heat of your hand.
Anyway he will be doing the measurements and then sending out the hpfp to another shop to get an estimate on the nicasil coating.
After I get the hpfp back I'll have to set up some sort of bench testing. I'm open for suggestons. Right now I know I'll have to set the pump up to flow diesel through it while turning the cam to simulate the approx rpm's of an operational hpfp.
Dwiesel did you get any quotes on the Nikasil coating yet? I am hoping that this coating will be the cure all for pumps that do not show wear, get em coated before failure! Heck if this works I might even consider getting that sportwagen I want!
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