Hydraulic system seals

[Bernie Benz]

If coming from underneath is most probably coming from one of the  
cylinder heads. Just replace the  O-ring sealing the leaking cylinder  
head. Or remove and replace O-rings under all 8, 2 in the front row  
for the PB and 6 in the second row for the PS. No need to open the  
pump any further.

These heads are needlessly very tight if not previously removed.  
Bentley says to use a drag link socket driver, but easier with a  
small cold chisel tapping around in the CCW direction to break it loose.

When replacing no need to tighten any more than with a big screw  
driver, won’t seal any better. ZF used the wrong O-ring, why all the  
sealing problems. Must seal on the ID of the housing bore, not on the  
OD of the head. use a generic 2-018 O-ring, available from any  
bearing or seal shop.

Bernie


On Dec 29, 2011, at 9:59 AM, SAJanesick - Bellsouth wrote:

> Bernie,
>
> Thanks for the info on the Nitrile.
>
> The pump has a substantial leak, about a drop a second while  
> running at idle, from underneath and not from the hose fittings.  I  
> lose about 3 ounces a day just in running around town so something  
> must be fixed.  Green blood is too pricy to waste.
>
> I considered rebuilding it myself, but didn't really have a way to  
> bench test it to 2100 psi.  I figure let someone with more tools  
> and expertise at it.
>
>                - Steve
>
>
> ----- Original Message ----- From: "Bernie Benz" <b.benz at charter.net>
> To: <PeterBergin at aol.com>
> Cc: <sajanesick at bellsouth.net>; <200q20v at audifans.com>
> Sent: Thursday, December 29, 2011 11:34 AM
> Subject: Re: Hydraulic system seals
>
>
> Your nitrile O-ring is just fine.
> Don’t have your pump rebuilt unless something is wrong with it. DFWAB!
> Careful with Audi rebuild kits, they use the wrong O-ring for the
> cylinder heads.
>
> Bernie
>
> On Dec 29, 2011, at 8:14 AM, PeterBergin at aol.com wrote:
>
>> I have rebuilt my pump on my old 200 twice.  Bought a seal kit  
>> (cheep)
>> from SJM)  did not do the shaft seal behind the pulley.  Need to   
>> get a drive
>> link socket and an impact wrench to get out the round plugs from   
>> the pump.
>> Kit is just a bunch of O-rings and seals. Not a hard job, less    
>> than 2 hours
>> the first time.
>>
>> Pete
>>
>>
>> In a message dated 12/29/2011 10:01:41 A.M. Central Standard Time,
>> sajanesick at bellsouth.net writes:
>>
>> I  recently lost a seal where the high pressure hose attaches to the
>> hydraulic  pump.  According to the VagCat board drawings, there   
>> appears to be
>> different size seals depending on which hose is attached.  I've   
>> matched the
>> size, but I am concerned about the O-Ring composition.  The seal   
>> that blew
>> out was a reddish orange seal versus the darker brown seal that  
>> is  used on
>> the hose from the hydraulic reservoir.
>>
>> Since it was over the  holidays, I just picked up a generic O-Ring
>> assortment from Harbor Freight and  indeed found the right size   
>> that seems to be
>> sealing with no apparent  leaks.  The O-Rings are black and  
>> package states that
>> they are made  of  Nitrile and resistant to oil, grease, etc.
>>
>> Does anyone have  any experience of using black Nitrile O-Rings   
>> within the
>> hydraulic hoses  fittings?  I've been told that Audi often uses very
>> specific O-Rings of  different color and material for different  
>> applications.  I
>> have not gone  to the dealer yet, but I could still get by there   
>> today or
>> tomorrow.  In  the meantime, I travel with wrenches, O-Ring   
>> assortment, towels
>> and as much  Chf11s as I can get my hands on - just in case.
>>
>> Also, I'm looking at  having the hydraulic pump rebuilt by LARES
>> http://www.larescorp.com/index.html  up in Minnesota.  From what  
>> I  can tell, they look
>> like they know what  they are doing, but I thought I'd check to   
>> see  if
>> anyone has any prior  experience with them.
>>
>> Thanks,
>>
>> - Steve Janesick
>> sajanesick at bellsouth.net
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