I´ve been searching the archives, and the general agreement seems to be that this hose is not vacuum, but just extracting air from the distributor to avoid fume accumulation.
I´ve seen my hose is broken, and I could hear hissing from it. Apart from inadequate ventilation, is there any other symptom that could be originated by this hose being broken?
I understand this hose holds positive pressure (blows, rather that sucks, if you know what I mean); could it be replaced with clear vynyl hose? (Can´t find vacuum hose with that inside diameter (too large)).
Cheers.
Carlos
PS: All this comes from a slow idle on cold startup investigation. I believe I have a stuck AAV, but I am exploring all other alternatives.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
2
Not totally clear on which hose you’re talking about. There are two on the distributor: One that goes to a small inline filter that’s open on the other end and serves as an air intake, and is simply laid somewhere on the LH side of the engine compartment. The other goes to a tap into the elbow that goes between the inboard panel of the LH engine air filter housing and the AAV. The little plastic fitting commonly snaps in half; it can be replaced with a brass fitting if you can find one. Better idea: Replace the elbow between air filter housing and AAV with an elbow that doesn’t have the attachment point – just cutting a piece of formed heater hose will work – and then reroute the hose from the distributor to its OWN connection on the air filter housing, which you will have to fab. It’s not hard to fab such a fitting, though.
When I fiddled with the distributor intake hose on my '83, I replaced the hose with a longer hose (fuel line) and relocated the inline filter to out in front of the radiator. Hence, it would be drawing cool air through the distributor. I figured it couldn’t hurt. I also replaced the plastic inline filter with a metal one and fastened it down into an existing opening in that horizontal panel in front of the rad.
What kind of metal filter did you replace it with? I was able to find an over priced oem filter which is really nothing more than the traditional filter back before I had any better knowledge about them.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
5
It’s just an inline fuel filter. I just looked over the selection at the local AutoZone and picked one with the correct size hose connections and a metal housing. I was pleasantly surprised to find the metal housing fit perfectly in an existing opening in the panel in front of the radiator. I drilled three small holes around the circumference for small self-tapping screws to hold the filter in place.
None of that is really necessary; you could just use a plastic filter and let it flop around in there the way Jaguar did.
Thank you all guys. I meant the vent tube that goes from the center of the distributor top to the curved hose in the air filter housing with the plastic fitting. I managed to connect the original hose. It seems to be OK.
The other vent line goes to a plastic fuel filter dangling in the engine compartment, as Kirby said.
Thanks a ton for the input.
However, my hissing is still there after refitting the hose, so I assume the AAV is to blame. It´s stuck, and gives no faster idle when cold (amazing to see the v12 idling at 300 rpm!).
We seem to cover this topic frequently, but pictures are very hard to come by.
I had some in the old photo-albums but they are now useless. Perhaps this: