Mystery hole in the side of my Aux Air Valve? Sucking in air

XJ
#1

While looking for vacuum leaks, I found a lot of air getting sucked into a hole on the side of the AAV. Covering the hole with my finger changes idle rpms same as any other vacuum leak.

I read a ton of threads here about AAV operation, and I’m starting to think this hole isn’t supposed to be there at all! It looks rough like it may have been hand drilled.

Second guessing myself… can anybody help me confirm if there should be a hole here??

I am comparing with online photos for this part # (Lucas 73174) which don’t show any such hole.
Here is a photo of mine, with a vendor photo of the same P/N showing no such hole.

IMG_0673
IMG_06734032×3024 1.81 MB

It’s a 1979 XJ6, series 3 but this P/N seems to be for a series 2 (in case that’s helpful).

Thanks! Rob

#2

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Put a sticker over the hole, Rob - and see what happens…?

The two versions of the AAV are obviously different - but I can’t think of any reason for that hole. The main idea is that the all air to the engine goes through the AFM - air from anywhere else is a vacuum leak…:slight_smile:

And welcome on board…

frank
xj6 85 Sov Europe (UK/NZ)
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#3

Aluminium tape on the hole would look good. It shouldn’t be there. And maybe it’s a typo?
There were a few FI S2, but the part and its job is unchanged. And the two look identical from the outside.
David

#4

Thanks guys - covered the hole with aluminum tape.

It looks like AAV operation is correct other than that - closed when hot, slightly open when cold.

I do wonder why somebody would drill a hole in the AAV, surely there was a reason, who knows.

On to the next one!

#5

An old tech hot carb type. Old rodder mod.
Drill a hole in the butterfly. Smoothens idle with multiple carbs and long intake tract. As well as a long duration cam.

Used on two four barrlels on a Wieand High rise!!!