VP37 Piston Stuck? Troubleshooting Guide.

Hello!

Today, I received a BMW 318tds from 1995 with some strange symptoms. The car arrived on a trailer, and when they showed me the 'defect,' I had to smile a little .

The car starts immediately, but it's running at full throttle. There's extreme black smoke, and it's running at full throttle until you turn off the ignition. It doesn't respond to the accelerator pedal at all.

I then tentatively opened the pump, which is a VP37 after all, and noticed that the metering finger was no longer seated in the actual piston on the rod inside the pump. Instead, the piston seemed to have twisted and jammed, making the recess or hole in that piston inaccessible to the finger. No wonder, then, that nothing could be adjusted.

I've had to disassemble these pumps several times before, but I've never seen a pump where the piston wouldn't move freely. Normally, you should be able to rotate the piston on its rod and push it back and forth, but here, nothing moves at all. It seems like the rod 'caught' the piston and turned it.
The problem is that there are two smaller rods with springs on either side of the central rod (where the piston is located), and the piston has twisted and become stuck between these rods.

Does anyone know if there's a chance to get it unstuck? I can turn the rod if I, for example, put it in second gear and move the vehicle, but the stupid piston is stuck. What would I have to disassemble to loosen at least one of these two spring rods on the left or right side in order to straighten the piston again?

I am grateful for any advice.

Ugh...

replace:

piston controlled by a slide valve (sleeve).
rod through distributor.

Then at least the words are correct.

It appears the slide valve is stuck. This doesn't look good. For some reason, that part must have come loose. Please take a close look to see if you can find any signs of damage or wear (and perhaps ask the owner about their fueling and maintenance habits). Are all the bearings on the actuation shaft in good condition? Is the eccentric still there, or has it broken off?
If the control slide valve is actually stuck on the distributor piston, the only solution is to replace it.

CU Gremlin.

uff:

"Some photos would be amazing."
I think that, including myself, there are probably several people here who have never seen the inner workings of the VP in such detail.

Regards,
Jan.

The distributor body, including the distributor piston and control slide (as shown in image No. 50), is only available as a complete replacement part!

CU Gremlin.

Hi Gremlin and all the others,

Can the pump housing be replaced on the installed pump? Or does it necessarily have to be tested on a test bench?


Does anyone know to what extent Bosch used equivalent parts for the pump head in the various VP37 injection pumps?

'To put it another way: Does a 11mm pump head designed for a mechanically controlled VP37 injection pump fit onto an electrically controlled VP37 injection pump?'

Can the pump body be replaced on the installed pump?

Okay, take a look at the exploded diagram and the photo.
'I really dislike disassembling small parts from the engine compartment, especially when they have to be reinstalled in exactly the same position.'


Does anyone know to what extent Bosch used identical parts for the pump head in the various VP37 injection pumps?
Here's the translation:

'To put it another way: Will a 11mm pump head from a mechanically controlled VP37 fit onto an electrically controlled VP37? '

Unfortunately, I can't tell you that. My documents don't go into that much detail.
I would be careful about that. You might want to check the catalog under 'parts for diesel injection systems' with the part number 1 987 720 013. Maybe that will help.

CU Gremlin.

@garth.brooks: Hello, you can't replace the pump head while it's installed, because you have to position the pump vertically (on a piece of tape or something similar). Otherwise, you won't be able to put the springs back in.
If you only replace the pump head, you don't need to have the entire pump adjusted.
But don't imagine it's that simple; the whole thing is quite complicated.

Hi!

Tomorrow, I'll be working on an Audi A4 1Z where the distributor head has developed a leak. I'll be replacing the sealing ring, and if I remember to bring my digital camera tomorrow morning, I'll take some pictures.

Best regards,

Hello!

Here are the pictures, as promised. The whole process is actually relatively simple and straightforward; you just need to make sure that the piston is properly seated when assembling it. Like, for example, the camshaft gear, the piston is fixed by a ratchet. If it slips out of place and you assemble the pump anyway, it will probably cause a major problem .

In a picture, the quantity adjuster, which protrudes from the top, is clearly visible. Its function is also easily recognizable; by moving forward and backward, it limits the flow of diesel towards the injection nozzles.

Here's one more tip at the end: Never try to seal the distributor housing with sealant; it definitely won't work, the pressure from the pump is far too high. A new sealing ring for 2 € from a Bosch service center is not expensive and will save you from having to disassemble and reassemble the pump again .

Here are the pictures:
http://dons.ath.cx/~marcel/vp37/

Greetings.

Hi, great photos - thanks!

Question: Does the piston then come out like that? Or does the control system still need to be removed?
If I understand correctly, it works like this.

What is the purpose of the screw on the front of the pump head? (The one that is inserted into the distributor cylinder, as shown in the diagram?)
Is she just inside, or is something going on?

When we talk about adjusting a pump, what exactly are we adjusting? Is it the position of the control slide relative to the measuring device? Or is there more to it than that?

If I measure the flow rate at the starting speed, say for 10 seconds, then change the pump head and subsequently check the flow rate again at the starting speed, and if it's not significantly higher than the previous value, then the motor should run properly at idle. Everything else is then determined by the performance curve, right? (Or is that nonsense?)
Does the position of the adjustment slider need to be adjusted relative to the measuring device when it is in that position?

One more tip at the end: Never try to seal the distributor housing with sealant; it definitely won't work, the pressure from the pump is far too high. A new sealing ring for €2 from the Bosch service is not expensive and will save you from having to disassemble and reassemble the pump again .


Oh, nonsense, there are only 900 bar on it .

or are you referring to the interior? It has a maximum pressure of 12 bar.
I'm still waiting for the pictures, my laptop only has a modem!

Are the images also a bit smaller for non-DSL users? Because none of these damn network providers offer DSL here.

Sure, here is the translation of the text from German to English:

'Cu Gremlin'

Okay, and from me as well, thanks so much for the photos, they're all great!

"If I understand correctly, the throttle valve rotates the shaft that engages with the control slide, right? This rotation of the shaft would then have a rather non-linear effect on the injection quantity. This would mean that the idle and full-throttle amounts could be controlled more precisely than the range in between, wouldn't it?"

We just need a few more photos of the disassembled pointwork .

Regards,
Jan.

Yes... I also realized that the 900 bar was a bit too much for my Hylosil ).

I've now uploaded a 'small' version of the images, which should work even for users with slower internet connections.

Best regards,

Hi,

Is the pump reassembled and working?

That would mean that the idle and full-throttle settings can be adjusted more precisely than the range in between, wouldn't it?


Actually, it's the opposite. The central area has the highest accuracy.
Precisely because the eccentricity causes the greatest deviation.

CU Gremlin.

Yes... I also realized that the 900 bar was a bit too much for my Hylosil ).

At that location, the maximum pressure is 12 bar. However, products like Hylosil and similar ones are not suitable for sealing surfaces like this. They only work on flat surfaces. An O-ring sits in a groove, and no matter how much sealant you apply, it won't work. You absolutely need the properties of an O-ring (a fixed shape, but also some flexibility) for that.

CU Gremlin.