Pressure Relief Valve Part Numbers

Hello.

Since the weather is getting warmer again, I finally wanted to replace the equal pressure/check valves on the distributor block of my VP37. But, as usual, it's impossible to get the parts from Bosch (just like with the injectors). I don't know if it's due to the part number, or if they simply don't exist anymore.
Could someone please, please find the part number for the valves? Surely, there are people in this forum who have access to that kind of information .
You won't find that in the online catalog.

Regards,
Jan.

G3, 1Z, 1994 (oval connector on the ESP).

I can give you the numbers later.

Here's a counter-question: What makes you want to redo those things?

Have you already gotten new nozzles? What difference did the change make?

m; - has distinct injector noises on cylinder 1 (12/95 - 158,000 km) and also wants to replace the injectors.

Hello.

Okay, I already have new injectors, and they definitely made a difference (different smell, a bit more power, and a slightly smoother running), but the harsh combustion noise that I have on one cylinder is almost unchanged (especially when the engine is cold and at idle) . Otherwise, my ESP doesn't show any signs of aging, so the valves are really the only likely culprits.
My car also has about 152,000 km on the odometer. It seems like something will need to be done at that mileage.

/Jan

Okay, I'm bringing this topic up again because I need some technical advice. I have the part numbers and prices for the equal pressure nozzles:
AGR: 028 130 795 J => 31.32 per share (the same applies to AFN).
1Z: 028 130 795 G => 80.00 per piece: ....

Okay, so here's the question: Does anyone know if the equal pressure valves from the AGR/AFN engine can be fitted to the pump from the 1Z engine? The injectors from the 1Z and AFN engines have the same opening pressure, and the pipe connections probably aren't different, right? (For 320 euros, I'd rather get a different pump.)
Could someone please take a picture of the parts on the AFN or AGR valve so we can see the difference?
Sure, I'd be happy to help! Please provide the text you would like me to translate from German to English.

best regards
Jan.

Yes, the "J"s are included in the AFN.

They must be crazy!

"1Z pressure relief valves and injection valves cost almost three times as much as the AFN parts?!?!"

m;

Yes, they do. I've asked twice. They couldn't tell me any difference at VW.
I can't imagine that there's a huge difference in the pressure relief valves themselves. They have to allow almost the same flow rate and maintain the same pressure. The question is whether the thread size or something else is different.
Since 1Z and AFN are extremely rare here in Denmark, I would be very interested in photos (of the AFN valves) so that I can compare them with mine. (Specifically, the valves attached to the pump. No one needs to unscrew anything ).

best regards
Jan.

I can offer 1Z and ASV (the ASV would be the Euro 3 successor to the AFN, but I have 220 bar injectors).

If I beg, I'm sure I can also test the ASV valves in the 1Z model.

m;

Hello Martin,

Can you see any differences between the valves when comparing the 1Z and ASV models?

dieselmartin wrote:

If I beg, I'm sure I can also test the ASV valves in the 1Z model. m;

Hmm, that would be amazing. One valve is already enough. If the engine sounds exactly like that, it should also work with four ASV valves.

/Jan

Hello everyone!

If the "inexpensive" pressure relief valves fit geometrically into the 1Z pump, then, in my opinion, there is nothing against using them.

The injector nozzles have different opening pressures in the first stage. The pressure relief valves, on the other hand, only have the task of maintaining the fluid pressure in the line at approximately 60 bar. Therefore, the valves have two main functions:

1. When shutting down the pump, immediately reduce the line pressure to ensure the nozzle needle closes properly.
2. Maintain a certain residual back pressure to reduce compressibility and prevent cavitation in the pipeline.

Even if the pre-tension pressure differs between the two types of equal pressure valves, this should be completely irrelevant to the operation.

Conclusion: Feel free to try it out without any worries.

Regards,
Alex.