Suction jet pump (vac) noise?

[5ktq]

Alright, my crank breather was cracked, the whole PCV system was thick with sludge, it was original. So yesterday I replaced the elbow off the crankcase / filter housing, the tee with PCV in it (and the PCV), and the suction pump. I desludged the metal pipe on the way up to the valve cover. Some sick bastard routed the vacuum system on this thing. I've got so many wounds...

Anyhow, I'm missing a few clamps (just for today until I can get them) so that might be it, but I hear a whistling from the SJP area now. If I pinch off the line between the pump and the intake, it quiets, so that is certainly the cause. But I'm wondering - does a normally functioning SJP whistle a bit? I'd kinda think the venturi thing might do that. But maybe I just have a vac leak.

[jacobsen]

No Audi owners are typically pretty pretentious and expectant. A whistling sound from the motor would not be allowed. The only thing that really can be described to whistle would be the turbo. Sometimes when you're boosting you might hear a little bit of a high frequency turbo sound.

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[5ktq]

It's a very faint air rushing sound, and pressing all the hose ends around the SJP doesn't seem to change it. only pinching the vac input to manifold part does, but I guess i must have a leak somewhere..

[jacobsen]

Inspect the hoses, your conclusion will be reached if you hunt it down. But it's normally a pretty silent functioning set up.

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[texasboy21]

Leak.

[jacobsen]

I notice the suction jet pump makes a thhhhh sound.

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[diagnosticator]

Is the noise most noticeable at idle speed? That is when the intake manifold vacuum is highest.

[5ktq]

Yeah, I can only hear it at idle, and even then it is hard to hear over the engine.

I put on some more clamps, and still hear it. Pinching either the output (to manifold) or input (from PCV) make it quiet so I think it must just be the venturi internal noise. neat.


I was going to use a stethoscope to narrow where exactly it is but I couldn't find the darn thing.

[All_Euro]

I’ve had brand a new suction jet pump leak... took me a bit to figure it out since it was new and I assumed it was good but when I sealed my hand around the one end, the noise of moving air went away. Replaced it (again) and the leak dissapeared.

[5ktq]

Hmm I did wrap my hands around it quite a bit with no change (and on every hose in the area).

It was a dumpster-grade 'mtc' one I had in the parts heap from my golf, so maybe it's just bad out of the box.