BOSCH VP Assembly: Questions & Answers

Hello,

I had a pump failure on my Ducato TDI (Bosch VE4).
Piston seized, guide pin on the lifting disc is damaged.

I have now reassembled the pump today using new parts.
Unfortunately, I only just realized that I haven't placed enough markers .

The drive wheel of the ESP can only be inserted into the timing belt wheel in one position.
The hub disc can be installed in 2 different positions .
How can I find out where the manufacturer intended the impeller to be positioned?


Furthermore, I have another question regarding the ring of the aggregate control system.
How is this correctly inserted onto the piston?

I installed the ring as shown here:
http://img406.

/img406/2086/vepzz1.jpg

Best regards, Rodion.

It's a shame that no one responded.
While I was lucky with the rotor blade, I managed to install it correctly.
However, the rule-enforcer put a stop to my plans...

I moved it up to the top of the photo, but it seems like...
Does this only apply to the VP37? In the mechanical version, it needs to be installed the other way around.
I'm now encountering the problem: flow rate = 0.
The pump only injects a small amount of fuel when the throttle is fully open, which is sufficient for a maximum speed of 400 RPM.

Fortunately, on the Ducato, the timing belt does not need to be removed. However, the starter motor, vacuum pump, etc. } do need to be removed.

Well, now I've learned my lesson, and something like that won't happen to me again.

Best regards, Rodion.

Luckily, I still had enough margin in the amount of fertilizer I was using...
The fact that the regulator slide was incorrectly installed...
I was able to resolve it by increasing the flow rate... Lucky again...

Hi Rodion,

Congratulations that the contraption somehow works. Given how little calibration/adjustment was done, the probability of it functioning correctly is close to zero. Normally, after careful repair and cleaning, it should be placed on a testing bench to ensure proper function.

"If the distributor body needs to be replaced, it must be re-calibrated, as it is subject to manufacturing tolerances just like the other internal components of the pump. If it is positioned too far into the pump, for example, the delivery pressure will not be reached. If it is positioned too far within the distributor body, it will make contact and damage the pump, which can potentially lead to the pump becoming completely blocked, with corresponding consequences for the drive system."

2.) Is it only the lifting pin of the throttle disc that has broken off? What about the linkage? Is it bent? It must fit perfectly and without any play into the corresponding slot on the control slide. The control slide, which acts as a metering element, must move with as little tolerance as possible, otherwise a smooth engine operation cannot be guaranteed. Furthermore, it must be in an exact position relative to the control sleeve, otherwise proper idle speed regulation is not possible. What other damage exists in the ESP that has not yet been repaired?

3.) What about debris in the pump? A violent break like that never happens without creating splinters. Where are they? If they had the opportunity to remain inside the pump, they would quickly cause damage, which could directly lead to a complete failure of the pump. Are you familiar with the size of the moving parts?

In principle, the design of all axial piston distributor injection pumps from Bosch and some other manufacturers is the same. I am not aware of any distributor body where the control edge of the distributor piston faces the drive shaft; that would be hydraulically illogical. Only the control of the control slide is electronic in the VP37, for example, which makes the VP4 and VP20 still mechanically controlled. The pressure generation and distribution are (almost) identical.

I once took two identical used fuel pumps and, without measuring them extensively, I modified one to act as a return pump. However, it turned out to be a distributor failure due to the fuel being too cold and the engine being revved too high. After 200 kilometers, I had to rip it out and replace it with a properly assembled pump, as the modified pump made it impossible to drive. I couldn't even reuse any parts of the modification, and the damage caused by the return journey also destroyed the parts that were still in good condition at the time of the crash.

"If you have any further questions, I'd be happy to answer them. However, I don't often have time to check the internet, so it would be more reliable to contact me by email, as the relevant thread might be archived too quickly. I can then gladly post a summary here or in another thread."

Smoky greetings.
Peter.

Hello Peter,

Thank you for the detailed contribution .

Test bench... I can do without it. I once inquired at a Bosch service center nearby.
I was told that with the older pumps, they only perform complete overhauls.
Everything else is nonsense . And those adjustments probably won't do anything either; it could be a bottomless pit .


1) So, he doesn't initiate the process or open the nozzles. Calibration is not an option for me, as mentioned above.


2) No, only the rotor blade was defective; everything else was fine.


3) The broken pencil lead was removed, and no wood shavings were visible.
However, the pump was still meticulously cleaned.



I just took the car for a test drive.
However, I don't have a tachometer, so I can only estimate the engine speed based on the speed in fifth gear.
Conclusion:

- Top speed is only 120 km/h instead of 160 km/h (and then it struggles to reach about 135 km/h).
-so it seems to be running at approximately 3300 RPM instead of 3800, the gears are just 'shorter' now.
-absolutely soot-free, in every situation.


I will now try to increase the production volume further.
Hopefully, there's still enough room to maneuver.

Best regards, Rodion.

Hi Rodion,

"I'm sorry if I was so negative before, but the more I work with these things and understand how delicate everything is and how it all needs to fit together, the more I realize the huge potential for errors when someone starts messing with an ESP without knowing what they're doing. I just had another one on my bench that someone had rebuilt, and afterwards, they were desperate because it wasn't working. All they needed to do was correctly attach the lever linkage to the control slide..."

You can adjust the distributor pump if you can adjust the injection timing. The problem is just getting the correct data. To be able to send you the data, I need the complete Bosch part number. If the ESP doesn't have a pre-injection function, a standard timing light adapter is sufficient. If it's a pump with pre-injection, it needs to be modified slightly for that, and then it will work. I have the tools to adjust all the settings in a mechanical ESP, but unfortunately, I don't have a test bench either, although it can often be done without one. I can understand why the diesel service shop might not want to "quickly" adjust the pump, because you can sometimes spend hours working on it without getting reasonable results, simply because something is wrong inside the pump or something else is misaligned by a tooth.

Regarding your engine's poor performance: I'm assuming that the valve timing is correct and that all the pathways for fuel and exhaust gases are in good condition.
- Is the start of the boost correct? A boost that starts too late can significantly reduce performance, even if the ESP is otherwise correctly configured.
- Is the throttle lever correctly positioned? Here, even being off by one tooth can result in a very noticeable loss of power, while being one tooth too early can cause a very high idle speed, to put it mildly.
- Are the idle and full load settings correct? Did you even adjust the full load setting? Is the throttle cable adjusted correctly? If the pump can't deliver full power...
- Is the fuel flow correct? If it's not producing soot when you accelerate, adjust the screw until it does, then turn it back a quarter of a turn. Somewhere in this archive, I have a guide on how to best adjust the fuel flow on mechanically turbocharged tractors. Usually, the "fine dust screw" (the fuel flow adjustment screw) should start tightening no more than two threads past the lock nut; that might be a helpful tip.
- If you haven't reached the original performance level by now, the pump needs to be removed, and the distributor must be adjusted. There's no other way to fix it.

Smoky greetings.
Peter.