FredR

Whilst playing around with my cooling system [separate post] I had some difficulty getting access to the header tank so decided to remove the vacuum actuated valve in the engine bay just under the header tank. Not too surprisingly, as I pulled on the actuator to remove it from the pipe that comes through bulkhead the pipe let go. Not sure how this pipe is supposed to be but on my car it is solid. Presumably petrol exposre has hardened it. Any idea how far back this pipe needs to be removed to effect a good repair? The inside of the pipe to the front solenoid valve is actually quite a small diameter. Cannot make much sense of this.

Not sure how this sub system is supposed to work but presumably it needs a vacuum to open this valve and then under some other coinidental condition, the solenoid valve that sits on the top front of the engine opens.

Regards

Fred

ammonman

Probably best to replace the hose back to the charcoal canister in the RF fender well above the windscreen washer fluid tank. Any fuel rated emissions hose should work. The vacuum valve ensures there isn't any fuel vapor flow from the charcoal canister when at idle. Shortly after the throttle plate moves off idle vacuum is applied to the vacuum valve, which opens. The solenoid valve gets a timed signal from the LH to control the volume of flow based on airflow rate sensed by the MAF. The higher the sensed airflow the longer the signal.

Mike

FredR

Hi Mike,

Thanks for that explanation-makes sense. I have not taken a look in there since I got this 928 but I believe it does not have that pathetically pissy little plastic y-piece. Would be interesting to know if silicon tubing has resistance to petrol fumes doubt it].

I must also check to ensure those vac pipe connections on the under side of the manifold are the right way round!

Regards

Fred