I've never understood why this hose is not part of the Samco boost hose kit.
Does anyone else supply one in silicon?
Does anyone else supply one in silicon?
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That is odd. The Samco's for the AAN have the ISV hose branched off the intercooler to throttle body hose, as can (just) be seen in this photo:
RS2'd 93 UrS4 5 spd sedan
94 UrS4 V8 6 spd manual avant -
This hose is the exit of the valve as it returns to the IM. It's the same for the 3B, ABY and Wagner IMs. Not easily visible when fitted.
Edit: Ok, looked again at your pic and I think I can "just" see the other hose going down out of sight below the valve. (I'm red/green blind so small quantities of red tend to disappear.
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good point, there was some Mod discussion on Samco recently, we should ensure this one is added to the listsigpic
1992 3b S2 CoupeComment
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I've got a silicone one, just bought an off the shelf 90° bend and trimmed it down. This is on a 3B, looks like the ABY might be a bit different.sigpic
1991 Audi S2 3B - 2.5 Stroker engine
1997 A6 2.5TDi quattro avant - C4
1976 RD250E / 350LC cafe racerComment
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Yes, I found a silicon one on the web and ordered it, looks like it will work ok, its a 19mm to 22mm reducer elbow.Comment
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N71 Idle Speed Stabilization Valve (ISV or ISS Valve) Info
Okay. Sorry. For the AANs, nobody makes a silicon hose for between the exit of the ISV and the intake manifold. In theory, with a properly functioning ISV, there is little or no boost going through the ISV and the ISV normally functions only at idle (under engine vacuum). I would presume that there is little need for a silicone ISV to IM hose for the 3B, ABY and ADU engines. Good luck.This hose is the exit of the valve as it returns to the IM. It's the same for the 3B, ABY and Wagner IMs. Not easily visible when fitted. Edit: Ok, looked again at your pic and I think I can "just" see the other hose going down out of sight below the valve. (I'm red/green blind so small quantities of red tend to disappear. )
N71 Idle Speed Stabilization Valve (ISV or ISS Valve) Info
RS2'd 93 UrS4 5 spd sedan
94 UrS4 V8 6 spd manual avantComment
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The ISV hoses, both sides, are subject to the same boost pressure as the rest of the inlet tract.Comment
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We aren't talking AAN and Newsh is right both sides will see boost pressure, can't see how you would not think so as boost entering the IM will try to go out the hose the other side of the ISV as it will have no resistance in terms of air flow.Comment
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I know the topic is not AAN but the ISV is the same, 3B, AAN, ABY and ADU. The ISV should be closed off idle (via the idle switch signal) and the only air passing through the ISV is based on the internal "emergency running opening". Yes at boost but flow should be small. If there is enough oil in that flow to cause the rubber ISV to IM hose to deteriorate, then replacing the hose is only a bandaid that is hiding a larger problem.
RS2'd 93 UrS4 5 spd sedan
94 UrS4 V8 6 spd manual avantComment
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Your still not thinking correctly your thinking it through, and thinking of the ISV operation only, this has nothing to do with ISV operation. Boost passes through the hoses pre throttle body and post throttle body via the connection to the IM even if the valve is closed.
If either hose has a hole you have a boost leakComment
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AFAIK this is probably the original hose from back in 1992 so it's sen some action, as I have a catch tank setup there is no oil in my intake any more. Circa 2 Bar of boost has finally taken it's toll.
Flow has absolutely nothing to do with pressure, the ISV and its hoses are subjected to exactly the same pressure and vacuum as the rest of the inlet tract. This hose should be part of a set of silicon boost hoses.Comment
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I understand the difference between flow and pressure.
The reason that I brought flow into the discussion is that is flow that would bring in the oily air that would deteriorate (rot) the hose, not pressure. And off idle, there shouldn't be much flow through the "emergency" opening.
If your original ISV to IM hose, item 29 in the RS2 diagram below (3B PN = 034133997J and ABY PN = 034133997AA, same as the ADU hose) has lasted 20 years AND you now have a catch can, then a new OE hose will last more than 20 years (past the end of oil). No need for Samco to build an overkill hose for that application.
RS2'd 93 UrS4 5 spd sedan
94 UrS4 V8 6 spd manual avantComment
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Agreed. It's still a nuisance that the hose is not included in a kit of boost hoses though, the whole purpose of a Samco kit is that you fit them and have no more split hose problems, ever.
I *think* that finding this small split has also fixed the small throttle stumble that I've had for a while..Comment
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Mine split on the inside seam.I had it of and inspected it a few times,and could not see a problem.
It was not untill I pressurized the system and could hear a hiss that I found it.
Itook it of and still could not see the split till I squeased it and it opened on the inner seam.right on the inside corner almost imposssible to see with the naked eye.
The 90% rubber bend on the metel part of the aan breater pipe is the same,I have it on mine at the moment.Comment
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