One-way valve on servo

[flow8rain]

Anyone know where I can get one of those plastic one-way valves (not sure what it is called exactly!) that plug into the front of the servo body and connects to the top of the engine via a rubber hose. I have an 89 S1.5 so assume the servo is from a Saab 9000. I am still trying to locate a 2nd hand servo as mine looks really cruddy but hopefully I can get away with just replacing the valve. I have tested the valve and it is 'one-way' no more so, I hope, that is the reason 1. Why my engine is running rough and 2. Why the brakes are really hard.

[GreenV8S]

I wouldn't be too optimistic if I were you. If the servo isn't doing its stuff that usually indicates that the servo itself isn't working properly - failure of the one-way valve isn't enough to stop it working. Similarly, failure of the one-way valve shouldn't cause the engine to run rough but failure of the diaphragm would.

[trackcar]

Peter's right .. My V8S has been running perfectly happily with a non-functioning one-way valve to the servo .. it's only an issue if the engine stalls on a very steep hill

[flow8rain]

Really not sure why engine runs rough. There's plenty of power there but it occasionally pops and bangs out of the exhausts and sometime struggles in the low gears at low speed (ie hops & jumps). My local garage have tuned the engine and cannot find any problem so, if by what you are saying, that if the servo diagphram is busted then that could be my problem. Guess i'm gonna have to try harder to locate a s/h servo or fork out £237.50 (+vat & p&p) to David Gerard.

[GreenV8S]

If the servo is causing the rough running then the problems will immediately go away if you block the vac line to the servo. It's a quick and easy test to do (bearing in mind that if you drive it in this condition, you will have unassisted brakes so public roads would be out of the question). There are plenty of other problems that can cause hesitation and rough running though, and just to assume that it's the servo because you can't think of anything else doesn't seem like a very reliable diagnosis.

[TimW]

Blimey Steve don't see you post here very often , still not running right then. I can't help much as I know bugger all about the 2.9, you've obviously done the throttle pot, checked the AFMs, obvious air leaks etc .

[HarryW]

Last post was me not Tim btw he's started to use my bloody firefox .

[TimW]

Only cos u cant fix IE..

[flow8rain]

Cheers guys, I am not just relying on using my servo problems as the only diagnosis - i've been here before and nothing is ever simple! I have tried running the car (not driving, just idling) with the hose from the servo disconnected and when the hose is blocked the car runs pretty good and when the hose is left open to the environment the car really struggles - as expected.

I've managed to source a S/H servo and master cylinder (£58 inc vat & del) so hope that will go some way to sorting this prob out.

For info, if anyone else is thinking about getting a S/H servo etc, I used find-a-part.com (or phone them on 09055642365). They were very good. There's not many SAAB 9000's being broken if the number of responses I got is anything to go by but there are at least 2 servo's and master cylinders still available out there - prices vary!

[grumpytvr]

Ignore this post, it would appear I have no idea what year it is. No change there then!!

I may actually remember that it is infact 2007 by March....................

Edited by grumpytvr on Saturday 13th January 18:45