Induction Leak

[UltraFlynn]

I need some advice guys.

At my last service I was told that I had "an induction leak" on the inlet side of the engine. Apparently to fix this the whole inlet manifold would need to be removed so the problem could be located and fixed. As it wasn't serious I decided that I would book this in to get fixed at some point in the future. (This I havn't done yet) In the mean time I have been setting about learning the location and function of each of those little vacuum pipes which snake around the engine to attempt to discover which might be causing this leak. (The eventual goal it to replace all this little hoses with brand new ones)

I reckon I can feel the affects of this induction leak as well when I drive. For example, cruising along at 1500rpm if I slowly accelerate at about 1750rpm the revs will jump to just over 2000rpm. It feel almost as though the gearbox has downshifted a gear when I know it hasn't. During more spirited driving you can feel this (to a lesser extent) at many places in the rev range.

As part of my investigation tonight I went out and looked at the modifications which have to done to plumb in my boost gauge. Using a picture from Martin's excellent boost gauge install write-up, I went looked for a similar modification on my car.

Here's what I was looking for: -



On my car I found this, which I'm thinking is most likely the same (or very similar modification): -



Now here's the interesting part. When I very very lightly pulled on this pipe the folllowing happened: -



The rubber of the pipe is really hard and it comes off very easily. It certainly doesn't seal.

So here's my questions: -

1. Am I right in thinking that "an induction leak" means a split vacuum pipe?
2. Is the modification of my car definitely for my boost gauge?
3. Could this possibly be my induction leak?
and finally 3. Would this very loose vacuum pipe possibly cause the affects on the engine which I mentioned earlier?

TIA

[Kev.O]

I'm no expert so can't comment on the other questions but I'm sure that's where the previous owner would have plumbed the boost gauge into.

[Martin F]

A1. It can be a split hose, but the size of the split would have to be relative to the expected level of induction leak, ie. large leak = large split.

A2. Most likely. You need to follow that pipe on the top part of the T and see if it disappears into your cabin (think yours is a mechanical gauge)

A3. I don't think so, but how long is the split?

However this aside it's a good idea to replace any split or hard pipes as what will happen is that they can be blown off when under higher pressure and then you will defenitely have a boost leak

It's their elasticity and pliability (they're great words for 11pm at night...LOL) which means they stretch round the ridge on that pipe and hold themselves in place, and seal tight.

[dunk shaw]

Think most car shops do this type of hose on reels so you can buy a couple of feet of whatever diameters you need and cut to length required, much cheaper and easier than ordering all the differant hoses off mr t

[UltraFlynn]

Thanks for the info guys.

I noticed on this photo that the pipe appeared to be split:



After checking this morning that split runs for about an inch up the side of the tube so there's definitely a problem. There certainly no way that there is an air tight seal.

I shall locate some replacement hose and then see if the problem goes away.

[Cass]

Matt I have all my old hoses sitting in my store room and they are all in good condition if you want them there yours.
Cheers Cass.

No Blue Relays tho!

[UltraFlynn]

Very kind of you mate. Let me see if I can get new ones near to work first, to save you the hassle of packaging them up. Otherwise I may well take you up on that offer.

[Cass]

Not a problem just give me a shout.

[Gambit]

In your first post Matt second picture you can see a split in another hose also as it joins the T piece, not massive but there is only one thing a split can do. Get bigger.

[UltraFlynn]

You're quite right mate. I'm going to replace all those hoses.