Annoying whistle on part throttle?

[Shilakadaddy 0]

I have a very annoying whistle on part throttle (sounds kinda like a fan belt slipping sound, but definately a whistle, rather than actually a fan belt slipping). I've removed the boost return and the carbon canister - both at the same time, and I'm guessing it has something to do with one of those.

 

I know other people said they got a whistle when removing the carbon canister, so assumed it was this.

 

Word of advice, I did this a while ago and noticed a very loud whistle whilst driving part throttle. This was due to blocking off the bigger pipe(*) coming out of the side of the throttle body under the inlet boost hose. Basically when the bypass butterfly is open the air passes over the hole for the pipe (*) and as mine was blocked very close to the throttle body it caused a whistle. Imagine blowing over an empty bottle.

 

SO, I've put a longer hose there and blocked that off so the whistle has been eliminated. You could even leave this open as its downstream of the btpass butterfly.

 

I also blocked off this pipe actually inside the pipe itself - hopeing this would get rid of the whistle, but apparently it didn't work. So remembering what Dubcharged said above, I connected a long pipe (the original pipe that was connected) onto it, and blocked the end of that instead. However it did nothing, the whistle didn't go away (and didn't even sound any different). I also tried removing the pipe altogether and not blocking it at all... but this had no effect either!

 

So.... I'm confused! :( Seems to me it isn't that pipe thats making the sound... but I can't tell what is, as it only does it when driving (I can't just rev the engine and make it whistle). Anyone know what it is, or what to do about it?

 

I've attached an image of the pipe I've been playing with, incase my description has got you lost and confused :)

 

Cheers, Chris

[24V Renshaw 0]

It will be the air whistling past the large vacuum pipe inlet on the throttle body. Try fitting something that fills the tube a bit rather than just blanking the hole.

Its a bit like blowing over a pen lid, the air rushing over it at part throttle causes the whistle.

 

Hope that helps.

 

Jay

[stevemac 0]

Shilakadaddy, what did you use to block the smaller vacuum pipes with (throttle body & inlet manifold) ??

[Shilakadaddy 0]

Try fitting something that fills the tube a bit rather than just blanking the hole.

 

Thats what I tried the first time.. although speaking to my dad about this he thinks it may be the material used. A small piece of brass was pushed into the hole (like a rod that filled the hole nicely, with a larger diameter end on it so that it didn't go too far in).

 

I used a similar sort of thing on the smaller vacuum pipe too. What I was thinking of trying was injecting silicon rubber into the pipe, covering the inside of the hole in the throttle body so that it doesn't go too far. That should completely eliminate the hole, whereas with the brass there was probably some gaps. Although it supprised me that the tone of the whistle never changed at all depending on what I tried...

[stevemac 0]

Shilakadaddy, blank off the smaller vacum pipe outlets with "diesel injector blanking plugs". These are exactly the right diameter/size, cost only a few pence each & just push over the metal outlets. :wink:

[Shilakadaddy 0]

cool, but what kind of store would these be available from? I don't think I've ever noticed that sort of thing before while shopping :oops:

[W3RKD 0]

cool, but what kind of store would these be available from? I don't think I've ever noticed that sort of thing before while shopping :oops:

 

mail me and i can send you some of the blanking caps for the price of a stamp chris.

[andycowuk 0]

[flame proof suit]

 

I have had this wistle for ages... iirc even before i removed boost return, but i recently got around to removing cc piping, and it got a load worse. Today, after getting poor numbers on the rollers, i was having a play with the ignition timming, I have retarded it a bit, and the whistle has all but gone. I still get it a bit, on about 3/4 throttle, ataround 1.5-2k but not as loud. I suspect i may have ben my ISV.

 

[2nd flame proof suit, for good measure]

[stevemac 0]

cool, but what kind of store would these be available from?

Either from Darren or from any motor factor or main dealer. These are universal plugs & are fitted to almost every diesel vehicle on the road, with the exception of the new "direct rail" injected diesel engines.

[Guest]

cool, but what kind of store would these be available from? I don't think I've ever noticed that sort of thing before while shopping :oops:

 

mail me and i can send you some of the blanking caps for the price of a stamp chris.

 

Can i have some too please Dr G :?: :lol: