Hydraulic pump cap tool

[Ameer Antar]

Thanks for the clarification. That definitely makes sense. I don't get the steering bit either... This is really making me wonder about those seals.
 
But I just wanted to point out that the bomb does actually have a check valve between the inlet fitting and the chamber behind the diaphragm. I think Kneale pointed out that it prevents fluid from going back into the pump. The SJM site has a nice cross-section: http://www.sjmautotechnik.com/trouble_shooting/brake.html#bomb
 
-Ameer 
-------------------- Original Message --------------------
From:"E. Roy Wendell IV" [erwendell at mac.com]
To:Ameer Antar [antar at comcast.net]
Cc:quattro at audifans.com
Date:11/19/06 11:45:55 PM
Subject:Re: Hydraulic pump cap tool

On Nov 19, 2006, at 10:45 PM, Ameer Antar wrote:

>
> I won't pretend to know all the details of that system, but what I
> do know is that after replacing the "rebuilt" bomb with a new one,
> I got my power steering and brakes back, and no more check system
> warnings. Looking at the diagram on SJM's site, it does look like
> the check valve prevents any back pressure on the pump, but I don't
> know if the servo actually puts pressure on that part of the system.
>
> The pump was rebuilt, but not by ZF. The tag was even removed from
> the pump. Other than the leaks, it's a lot better than my old one
> which probably had a bad front bearing since the pulley was
> wobbling all over the place and squealing up a storm. The seller
> claims the seals were replaced, so I wonder what I'll find under
> those caps. Either dried up seals or ones ripped up by strong
> backpressure... Or who knows what else... For now I'm stuck having
> to top up the liquid gold every week. Last week, I had the car in
> the shop and they filled it for me cuz they got the check system
> warning: $20 for a top-up! I didn't argue... at least they didn't
> put in transmission fluid...
>
> -Ameer

Just a few clarifications:

The check valves for the brake hydraulic boost system are in the pump
itself. There is one for each of the two pistons underneath the allen
head caps next to the X caps.

The bomb doesn't have a check valve; it has a pressure relief/
pressure regulating valve. If this is stuck open the system will
never build up pressure. If it's stuck closed then the high pressure
hose from the pump to the bomb and or the seals under the X caps will
blow. This results in green goo everywhere and a permanent green tint
to the garage floor. BTDT. Judging by your description you had a bomb
with a valve that was stuck open so that the system never built up
enough pressure to assist with brake application. This should
actually cause less stress to the seals under the X caps.

I'm not sure how a bad accumulator could affect the steering system.
The steering system circuit is separate from the brake boost circuit
except for sharing a common reservoir. The pump is essentially two
pumps that share a common shaft.

Roy Wendell
erwendell at mac.com
Too many type 44 tq
A pair of MR2s