End of a 12mm pump! WHY?

Hello!
A year and a half ago (25K km) I buildid 12mm pump:
In good condition pump
New shaft bushes
New seals
New 12mm bosch head (made in Germany)
Strongest springs what I find (TDS I thiks)

And now there are lot off metal inside the pump, I thought I have broken spring or bad camplate roller but NO.
There are small wear in lift pump but really bad damage in shaft and cam plate connection. there were half of the pump locking holes (3 mm) off a slack.
There are some small damage in plunger to.


I uploaded pictures:
https://photos.google.com/album/AF1QipMQQ_ElKuEyWDPVTNvSfGYJa2-FM-iFuGQpRgn9

Any ideas why this kind of wear/damage?

Sorry for my bad English!

what nozzles?
you need very very large ones to have reasonable peak injection pressures
opening pressure does not matter, peak pressure is many times opening pressure

that surface slides in and out while under peak load from each injection event, fuel lubricity may have played a part in the failure but my bets are on too high of injection pressure

edit to add: that cross piece looks odd to me, are they not usually a machined piece rather than sintered?

Jeah we have quite bad fuel....
I used 0.240mm nozzles, some engines what are using 12mm head are using to 0.240mm nozzles. (Now I have 0.260 nozzles)
I reduced my fuel map something like 30%

I thought that factory automatic pump with 11mm plunger, higher cam lift, 0.158 nozzles and higher fuel maps shuld stress parts more...

12mm pump heads really really hate life above 2000 pump RPM, you need to treat them much more kindly than 11mm
with that small of nozzles you're very much better suited by an 11mm pump head, only reason you run 12 is to get reasonable spray out of nozzles larger than .300
even then you can usually coax more power from 11mm/de143 because it will last at 3000+ pump RPM, where the engine and transmission needs to be spinning in order to survive making big power numbers

I did everything to try and make a 12mm pump last and it just kept seizing. I ran .340 nozzles set rev limiter to 5000rpm and ran 2 stroke oil in the fuel but never lasted long. I swapped to a 11mm and set rev limiter to 6000rpm and it never gave me a problem. Always ran a Fass 150 lift pump set at 30psi.

Unless your running full wot on huge Injectors, a 12mm is pointless

BigTurboAlh said:

Always ran a Fass 150 lift pump set at 30psi.

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interesting, cummins VEs spit the front pump seal out around there
I've been running 15-20 psi on mine

on the lubricity, I'm running 80% waste ATF and 20% gasoline through mine as fuel. Might be good, might be bad. Got maybe 40-50k on the same chinese pumphead running it though

250 hp with some good parts and a 11mm pump
this is not enough? 12mm pump ?
oh i get it
BUT ITS 400HP!!!!!!!!!!!!!!

@486 I put red loctite around the seal and staked it and I’ve never had it come out. It’s been a while I sold my old truck with the alh and compounds

Well seems like 11mm pump is good at least for 440hp from the engine. Never seen any big power results from 12mm.

If I am not mistaken the 12mm pump head is chinese, and junk.

For the price and hassle, an 11mm pump with some water/meth and NOS would easily bump into the 500 area but at this price point, serious engine modification is needed. I never understood why people insist that bigger bolt kn parts mean better performance. It's not about "give me all the fuel" it's about how to burn it!
Even on my 944 engine ahu build, I'm shooting for 450hp but still going with an 11mm pump! I wanted a 12 because "racecar" but soon as I drove into it and talked with runners and the guys who build these over in Oregon, consensus is that an 11mm is best and the 12 is garbage. Heck I was making 230hp on basically stock internals with minimal head work on the stock 10mm pump and red lining at 6200rpms
Imo the IP is one of the last things you upgrade from stock once everything else has been done.

Scott_DeWitt said:

If I am not mistaken the 12mm pump head is chinese, and junk.

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there are numerous applications for them from bosch and zexel, just not many will shell out the money for them

BigTurboAlh said:

I did everything to try and make a 12mm pump last and it just kept seizing.

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What springs did you use?
My pump heated fuel quite a lot first 500 km so I didn't push it at that point.
I'm using only PD lift pump, but was monitoring pump inside pressure some time.

WarmStart said:

What springs did you use?
My pump heated fuel quite a lot first 500 km so I didn't push it at that point.
I'm using only PD lift pump, but was monitoring pump inside pressure some time.

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I believe they where springs out of a 10mm pump. I used camplate out of 11mm pump. If I were to try it again I’d try the 10mm camplate. It might last a little longer

my springs are bosch 1 467 010 410
just read somewhere that they were 'the' springs to use

We all have noticed that clear fuel is going in but bubble fuel is coming out of the pump.
In some point there are some kind of vacuum on top of the plunger when there are filling time. 12mm head is making bigger vacuum than smaller ones and are pulling more air out of the fuel.
Even if pump inside pressure is more than 15 bar.
Plunger filling port are really narrow and biggest problem is pump own lift pump, it can produce pressure but it won't flow enough fuel.
Pump own lift pump is producing air to, if you do not use good tank lift pump.
12mm head is seizing because there isn't enough fuel to feed it.

Depending on just exactly wherre the IP is getting fed fuel, you can run up the pressure a lot. There were a few Cummins folk running 300+ psi in search of some big, 'fuel only' numbers. They succeeded rather well IIRC, but those are not quite turning the rpm these we TDI's are often doing.

What y'all need is a 12mm, P7100 hung off there...
cheers,
Douglas

WarmStart said:

Plunger filling port are really narrow and biggest problem is pump own lift pump, it can produce pressure but it won't flow enough fuel.

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I've thought of removing internal lift pump, blocking off passages and hooking the original inlet to the return line so bleed off pressure past the shaft does not pop out the shaft seal
then using an external pump to supply case pressure. Possibly the power steering pump, as it is slightly larger in displacement and also spins faster than engine speed rather than 1/2 engine speed.
The pressure regulator in the p/s pump is also very easy to adjust for different pressure with a change in the small spring against the check ball

PakProtector said:

Depending on just exactly wherre the IP is getting fed fuel, you can run up the pressure a lot. There were a few Cummins folk running 300+ psi in search of some big, 'fuel only' numbers. They succeeded rather well IIRC, but those are not quite turning the rpm these we TDI's are often doing.

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case pressure in vp37 is already something like 200 psi,
just single element needs to fill 4 times per pump revolution where an inline only needs to fill once

I've had a 12mm pump in my car for nearly 7 years with the stock AFN 205 injectors without issue. Can't say there's any secret combination of components or tricks to keeping them alive. Mine has been daily driven for over 120k km. I know what I never do is rev the crap out of the engine, and the TB should be replaced more frequently than normal just to be sure because of the extra loads on it.

TDIMeister said:

I've had a 12mm pump in my car for nearly 7 years with the stock AFN 205 injectors without issue.

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...why? Seems like a lot of compromise for next to no gain.

The only failure I've had so far that left me walking was siezing a 12mm head with pp764s. Didn't happen for a couple thousand miles, until I bumped up the very low fueling maps I'd put on, then first trip out it immediately happened when I got it to request enough fuel. I'd blame too high of peak pressure causing case flex.

[486] said:

...why? Seems like a lot of compromise for next to no gain.

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Because I like the idea of getting the added performance though better fuel atomization with higher injection pressure from a bigger pump and not going with super large hole nozzles if my performance goals don't warrant it and/or long injection durations (my car still has the original, AFAIK 22 year old turbo and a slipping OE clutch).

That's the order that I will always follow increased fuelling: injection pressure, nozzle size and duration last (or don't alter the duration from stock at all if I can avoid it). I'm following the approach of VW Motorsport's own TDI endurance race car program from over 20 years ago.

WarmStart said:

Strongest springs what I find (TDS I thiks)

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I'm pretty sure this is the source of your problem.

And now there are lot off metal inside the pump, I thought I have broken spring or bad camplate roller but NO.
There are small wear in lift pump but really bad damage in shaft and cam plate connection.

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Could be a manufacturing defect, but also sounds like high axial loading and camplate wear from excessive Hertzian pressure.

http://forums.tdiclub.com/showthread.php?p=1175622&highlight=Hertzian#post1175622

[486] said:

that surface slides in and out while under peak load from each injection event...

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But how to avoid this problem or how to make it stronger?

Nitriding as they are doing with camshaft?
Grinding more material off and weld on some really strong material and machine it?

WarmStart said:

But how to avoid this problem or how to make it stronger?
Nitriding as they are doing with camshaft?
Grinding more material off and weld on some really strong material and machine it?

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Why? A 12mm head is pointless on all daily driver. It's the same as trying to make a drag clutch work for a street car or drag slicks . 12mm heads have their purpose. And that is on a tdi that's going to see mostly wot aka a drag car. And at this point other prompts end up being installed. Like a Cummins pump.
Imo 11mm or something better. Not a 12 u less its application specific.
I have seen some use a 13mm head and the results are even worse.

WarmStart said:

But how to avoid this problem or how to make it stronger?
Nitriding as they are doing with camshaft?
Grinding more material off and weld on some really strong material and machine it?

Click to expand...

I'd bet on something like TiN or DLC coating making an improvement, but what I'd bet failed first was the cross piece coupling, then the rough surface wore the camplate.
Try and find an old coupling from a much earlier pump that is machined from solid rather than sintered metal. Be aware though that very early ones have a larger hole in the center which does weaken them.

Barring that, you could get one made from 8620 and have it carburized for an extremely hard surface with a nice tough interior.

I'd bet on the camplate already being made from the best alloy available. That sintered coupling however just screams cost-cutting.

Finally made some "science" with plunger springs!



I got them from my friend. He thinks they are from VP30...
Can someone confirm VP30 spring measurements?

A few general rules of thumb when it comes to spring rates versus different dimensions relative to the uncompressed condition:

- Thicker wire = higher rate (duh!)
- Smaller mean diameter = higher rates (counterintuitive)
- Wider pitch (turns per length) = higher rate.
- Thicker wire and narrow pitch gives less margin to coil bind (solid height).
- Measures that increase spring rate except for larger wire diameter increases stresses for a given load, reducing the margin to fatigue failure.
- High length to diameter ratio can lead to buckling and stress concentrations that greatly increase likelihood of failure.

Of course, Bosch knows this in the pumps they engineer for each application. It's when people mix and match parts seeking a certain outcome in isolation (eg higher spring rate) and drive the pump way outside their design parameters (eg RPM, pressure) without considering and understanding their consequences that trouble happens.