Audi A4 Leak: AHH VP37 Repair Guide

Hello everyone,

The VP37 on my A4 is leaking.
Under the MSW.

If this is already leaking, then more areas will likely follow.
Looking for a way to seal something in the Ingolstadt area.
Are there any recommendations?

Thank you in advance for any advice.
Best regards, Peter.

Hi.

You're unlikely to find offers from people doing illegal work here, and a sealing job done by a company like Bosch & Co. would probably cost between 800 and 1000 euros.

Alternatively, a "refurbished" pump from eBay sellers could be an option for under €300.

Best regards, Rüdi.

Falls es wirklich die Dichtung unter dem MSW ist, die läßt sich ohne zu großen Aufwand tauschen. Du mußt Dir nur zutrauen, das Mengenstellwerk abzunehmen und neu zu justieren (sh. Facarticle).
Bosch offers a set of seals for around 20€ (e.g., 2 467 010 003).
VCDS is recommended for adjusting the MSW.
hg
Herbert.

Thank you very much for the answers.

Yes, I'm certainly confident in my ability to handle the mechanical aspects.
I've already replaced the gasket under the lid once, about 3 or 4 years ago. Now, it's leaking again, one level lower.

The poem is already on the desk... for months .

"Refurbished" pumps from the bay... no thanks. I bought a "good" rebuilt transmission with a warranty. It lasted 2000 km, and then the differential seized! And that was 1000 km away from home!

However, since I only have Apple devices in the company, the VCDS software cannot be installed because it won't work.
[Edit: It seems it is possible after all, keywords being Bootcamp or VirtualBox.]


Perhaps, but actually... my daughter has a Windows computer/laptop.
That might work.

Best regards, Peter.

Hello everyone,

I'd like to provide a brief update.
Thanks to the expert articles in this forum and a few videos from YouTube, as well as a S101 model from autodia, I was able to successfully replace the seal under the MSW.

Important: The menu navigation in the S101 is quite archaic, meaning it is not as user-friendly as in VCDS.
However, it was possible to "deduce" that in the engine management system, within measurement block 1 where the engine speed is displayed, my reading was 861 RPM. Also, the displayed fuel quantity of 0005.00 mg/H likely indicates 5.0 mg per stroke.

Then there's the mechanics, which have been described and shown countless times:
- Use the diagnostic tool to record the current values, and I will take photos with my phone.
- Make sure to clean everything thoroughly.
- Mark the approximate position of the MSW (Mandibular Sacroiliac Joint) with a needle or similar tool.
- Unscrew the return line.
- Slightly loosen the inlet valve and turn it off.
- Unscrew the securing point for the electrical cables.
- Completely cover and seal the area with rags or paper, and collect any spilled diesel fuel.
- Then, unscrew the MSW (main system module). A special screw from Bosch is included, and there are many solutions available online.
- Out with the old, in with the new.
- and now comes the tricky part, threading the needle. I practiced a few times until I was sure I had caught the small hole properly.
- The engine started immediately, but it ran very roughly.
- Tighten the screws and use the diagnostic device to correct the position. After the initial adjustment, the engine immediately ran better, and it was almost acceptable at 2.0 mg/H.

Beginner's luck. I managed to get the original setting of 5.0 mg/H back.

Let's see if this gasket actually seals the leak in the ESP (Electronic Stability Program) system.

Best regards,
Peter

Now I'm thinking about VCDS, because a diagnostic tool like the S101, which costs around €130, can be significantly cheaper than the VCDS software. The S101 is borrowed from a colleague who uses VCDS... he doesn't have any older models like mine anymore, and in his Golf I Cabrio, the heart is a 1.8T Audi engine... a somewhat inflated heart .

Hello everyone,

a progress report.
The leak underneath the MSW is likely gone.
However, I still probably have a leak between the pump and the high-pressure unit.
If I decide to do that, I will report back on the results.

Best regards, Peter.

Hello everyone,
My first attempt to create "great poetry" between the two ESP parts (ND/HD) didn't work as well as I had hoped.
As I was almost ready to see the seal on the HD part, I noticed that the HD part was a little loose. At that point, I lost my nerve and reassembled everything.
And then things got really serious.

VENTILATION!!!

I think I've just become spoiled by the mechanical fuel injection pumps that are installed in my old Daimlers.
If the pump is completely empty, it takes a very long time to bleed the air out, and a 100Ah battery is not sufficient for that.
I was dragged by my father... for 4 km.
Then the engine started briefly and wouldn't shut off... until I loosened the supply line to the ESP a little.

QUESTION: Can the HD component be loose, as long as it's secured by screws, or is it still held under tension by the springs inside? In other words, is it allowed to wiggle slightly?
Yes, I've already pre-tensioned the ESP's "internal components." You observe the internal components, and in 5th gear, you slightly accelerate the car. When the MSW (presumably a modification or sensor) is removed, you can see when the large disc reaches its rearmost point. At that point, you can be sure that the components remain under tension.

BUT: What about the HD part? How far can it protrude from the ESP enclosure without causing the internal components to interfere with each other?

Thank you in advance for all responses.
Best regards, Peter.

Based on experience, you can usually remove the HD part far enough to allow you to detach the seal (e.g., by carefully prying it loose with a small screwdriver).
The HD part should be secured with two screws in a diagonal arrangement.

I do it this way: I put the new seal over the HD head and then assemble it.

It's difficult, but it works. However, you're always a little afraid that the O-ring will break.
Ideally, use it when it's warm, and gently stretch it by hand beforehand.

Then, move the two diagonal screws to the other mounting points.

Make sure to work cleanly!

Lightly oil it, and carefully tighten it back in place.
Above all, it should be even and without any slipping.

Nevertheless, without any guarantee!

...I did all of that the same way.
That's why I bought two of these seals, in case one breaks.

And I wanted to soak the fabric in warm water for 30 minutes beforehand.
Warm, not hot.

Best regards, Peter.