How to Identify Fuel Injectors? - Viton vs Metal tipped

Jim Dupree jdupree914 at
Mon Sep 18 20:54:18 EDT 2006

Viton is a rubber the seals and last well but Audi is
not talking about the injector seals ( grean or balck)
in this case. They are talking about the sealing of
the spray tip of the injector, an improvement to and
cinternal seal to reduce the occurance of injectors
leaking and dribbling. Since the changes are internal
you will not be able to see a visual differnce except
for the part numbers. I though Audi had quit suppling
non-viton injectors but who knows. Here is the begin
text from and older TSb from Audi about testing
injector, it list part numbers fro viton injectors
(also say part number are for reference only...
yada... yada...)

Group: 25
Number: 91-08
Date: June 30, 1991

Viton Tipped Fuel Injectors, Injection Quantity,
Comparative Measurement

Model(s): All with CIS, CIS-E, CIS-E III m.y.

This procedure for comparing fuel injection quantities
applies to the following Audi vehicles if equipped
with Viton tipped fuel injectors:

All 4000 1985 - 1987 
All 5000 1985 - 1988 
All Coupes 1985 - 1988 
All 100 1989 - 1991 
All 200 1989 - 1991 
All 80/90 1988 - 1991 

 - check part number stamped on barrel of injector

Note Two types of fuel injector are used in these
vehicles: Viton tipped and metal tipped. Viton tipped
injectors will have one of the following Bosch part
numbers stamped on the barrel of the injector:

0-437-502-043 High pressure (replacement) 
(Audi replacement, Part Number 035 133 551F)
0-437-502-044 High pressure (OEM) 
(Audi replacement, Part Number 035 133 551F)
0-437-502-045 Low pressure (replacement) 
(Audi replacement, Part Number 026 133 551)
0-437-502-046 Low pressure (OEM) 
(Audi replacement, Part Number 026 133 551)

If injector does not have one of these part numbers
 - it is metal tipped, check using procedure in Repair
Manual, Group 25, Section 25-55

Part numbers are for reference only. Always check with
the Parts Department for the latest information.

Notes regarding Viton tipped injectors:
 - They can be used as a replacement for metal tipped
injectors but only in complete sets
 - The fuel absorption characteristics of Viton
requires different testing considerations than metal
tipped injectors

Good Luck

--- Huw Powell <audi at> wrote:

> > How do you identify viton tipped from metal tipped
> injectors?
> > What the hell is viton anyway? Is this a plastic
> seat that the metal valve
> > rests against?
> I'm just chiming in to say that the Viton is a green
> rubber compound 
> that lasts better than the black stuff.
> It doesn't make sense to me that it would be
> contrasted with "metal". 
> There are two o-rings, one around the metal tip
> shroud and one where the 
> main body pops into the head (or manifold, on some
> cars).
> -- 
> Huw Powell
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