Vacuum Tube Adapter N75: 3.5mm to 4.8mm

Hello,

I have a rather specific problem: the vacuum hose to the VTG (Variable Turbine Geometry) valve on my TDI is cracked or worn.

"That wouldn't be a problem at all; I have both the thin 3.5mm fabric hose and the 4.8mm fabric hose in the thicker size that goes to the EGR valve."

Fortunately, the same pneumatic converter is used for both the EGR valve and the turbocharger boost control valve – and it has a 4.8mm thick control outlet.

Out of the factory, the N75 is equipped with a hose that initially has a diameter of about 5 cm and then tapers down to a thinner section.

Since I'd like to replace it with something cost-neutral using existing parts, my question is: has anyone ever seen a socket adapter from Volkswagen?

"So, these are vacuum hose connectors that can connect from a diameter of 3.5mm to 4.8mm."


Alternatively, I'm considering buying a 3.5mm connector and attaching the hose to both sides, using some sealant on the 4.8mm side, and then securing it with a clamp.


Does anyone happen to have a part number handy for a 3.5mm connector, or perhaps even a part number for an adapter?


Greetings.
George.

Hi Georg,

I don't think you'll find what you're looking for at AuWeh; they want to sell their special hose for a high price.

Take a look in the aquarium section; you might find what you're looking for there.

You can probably find them from other suppliers as well; Landefeld was just the first one that came to mind. And the local hardware store might be able to order them if they don't have another source already.

Smoky greetings.
Peter.

Great! This is exactly what I was looking for and couldn't find! Perfect, thank you.

I'm curious to see if I can get the hose off the N75 valve without damaging it – unfortunately, that's already happened to me once before... the connector broke off.

where I think this time I'll cut the hose with a scalpel; that's preferable to me, rather than having to spend €40 on an N75 valve .

Octavia_4x4 wrote:

I'm curious to see if I can get the hose off the N75 without damaging it – unfortunately, that has happened to me before... the connector broke off. where this time I think I'll cut the hose with a scalpel; that's preferable to having to spend €40 on a new N75

. Yep... and then apply some silicone grease (!) to the nozzle before sliding on the new hose. The silicone prevents/delays the bonding between the hose and the nozzle, without dissolving rubber or similar materials (as is typical with mineral oils & greases).
This connection can still be relatively easily disconnected even after many years.

Hello Ulf,

Good tip, thank you . I've temporarily repaired the hose with a shrink tube so that I can at least drive the 150 km to work tomorrow; it should hold until the replacement arrives.

How does it actually work when it goes into emergency mode again because the control unit is malfunctioning – if I continue driving in emergency mode, am I usually not damaging anything, right? The protective functions should kick in exactly at that point.

It doesn't always have to be good! For example: Rubber seals, which were used with silicone grease for easier installation, are swelling in large numbers inside coffee machines and becoming leaky. The lifespan, for example, of DeLonghi/AEG/Privileg models that are still relatively current is about 3 years. At that point, they're out of warranty and start leaking into the electronics. If noticed early enough, replacing the swollen rubber rings with silicone rubber rings and reassembling them with silicone grease can fix the problem. If it's noticed too late, there will be a "bang!" and the control board will break. For most owners, this would represent a total loss.

By using one or two layers of heat shrink tubing, you can also adjust the thinner sleeve to a suitable size.
Best regards.
Herbert.

Quote:

Fortunately, the same pneumatic converter is used for both the EGR system and the turbocharger control valve in this car.

I would be careful there; these pressure transducers often have an additional additive (usually "A").
The (test) resistors are different.

Hutfahrer wrote:

Rubber O-rings, which were used with silicone grease to facilitate assembly, are swelling and becoming leaky in large numbers of fully automatic coffee machines.

Well, that surprises me somewhat. In my car, I haven't had such problems with silicone spray so far, but I definitely have with mineral oils and greases.
The rubber plunger seals on my large VTG and AGR test syringes also quickly swell to the point of becoming unusable with common lubricants, but they have been tolerating my silicone spray from E-Coll for years.

Can you confirm that the grease used for the coffee machines does not contain any mineral components?

RedR32 wrote:

Quote: Fortunately, the same pneumatic converter is used for both the EGR system and the turbocharger pressure valve in this car. Uhh, I would be careful about that; the turbocharger pressure converters usually have an additional component (A). The (test) resistors are different.

In practice, however, they can still be replaced without problems (at least sometimes).

I used silicone grease from the "gas-water-stuff" section, which is advertised as being food-safe. However, in relevant forums, you often read that hoses or rubber seals swell even with supposedly suitable silicone grease. In some cases, this happens even with the stuff that was originally used by the manufacturer as assembly aid. Intentional?? For later maintenance, there are "durable" rubber seals available as replacement parts. In this case, it's better to go for the aftermarket parts and definitely not install "original" ones.

Okay,

I went shopping today and found the right hose fitting here at the aquarium supplies store; that tip was really helpful. I'm going to assemble it later.

I built my hot water windshield washer system using aquarium accessories. You wouldn't believe how well the pre-heated windshield washing water cleans the glass.

Tip: If the hose is difficult to pull off, you can carefully cut it open with a knife from the side without damaging the connector.