Disco 1 V8 whistle

[Utemad]

My 1994 3.9 V8 Disco has a whistle. It has been doing it for months but I cannot pinpoint it.
It is coming from the engine bay and the whistle occurs when you lift your foot off the accelerator pedal and the engine is reving from moving. For example if I accelerate from the traffic lights there is no whistle. As soon as I lift my foot from the pedal it starts to whistle. It does not stop until you either touch the accelerator pedal again or return the engine to idle. It takes a few seconds to stop once returned to idle though.
It is loud enough to be heard from inside the cabin with windows up.

As I cannot replicate it very well by reving the motor and letting it return to idle it is proving difficult to find. I was thinking it is a vaccuum leak but I'm just guessing. Is there any common places to look for persihed hoses or leaks of any kind when this occurs?

[BigJon]

It certainly sounds like a vacuum leak. The first step would be a thorough visual inspection of all the vacuum hoses.

[Blknight.aus]

vacume leak the easiest way to find it is with the wifes vaccume cleaner...

remove the MAF (carby or equivelent) and tape the vacume hose to the remainder of the inlet manifold.

stick a potatoe into the end of your tail pipe(s) and with the vacume cleaner as far away as possable and with something between you and it as a sound dampner turn it on..

a, make sure that you have the potatoes only just over the end of the pipe(s)
b, make sure the vaccume cleaner can breath, if it has one of those little holes that can be opened to stop you creating no flow open that up..

you should find said leak in no time..

[rangieman]

You can also spray around the engine with a wd type spray with the engine running and when the revs increase you are close to the source
dont go near the exhaust (fire):D

[Utemad]

Thanks guys. At least you think it is a vaccuum leak as well. Our vaccuum doesn't blow so I can't try that one out. Sounds fun though.
I've already had a look at the vaccuum lines for leaks but not found anything. Might spray around some of the connections and see what happens. Would aerostart type sprays be good for this?

[Blknight.aus]

you dont want it to blow, you want it to suck....

instead of the air going in past the MAF or carby or whatever else and then into the engine your going to be trying to pull it out of the engine through the intake manifold to find the leak...

get this this is the cool bit

(apply sarcasm font)

your using a vacume , to create a vacume....

(remove sarcasm font)

now if only I kud spel.

[Utemad]

you dont want it to blow, you want it to suck....
(apply sarcasm font)

your using a vacume , to create a vacume....

(remove sarcasm font)

now if only I kud spel.

Okay I get you now :D

I just assumed that since air normally goes in that hole that you would be blowing. Plus having the spud in the exhaust would stop it coming out there thus trying to push itself out the vacuum leak.

I must admit I was thinking what would happen if the vacuum cleaner blew dust into the engine since we had now bypassed the filter :confused::)

[rangieman]

Thanks guys. At least you think it is a vaccuum leak as well. Our vaccuum doesn't blow so I can't try that one out. Sounds fun though.
I've already had a look at the vaccuum lines for leaks but not found anything. Might spray around some of the connections and see what happens. Would aerostart type sprays be good for this?


No dont usw areo start i think its to explosive use a wd type spray im trying to stay away from name brands but crc or wd40 or something from the 2$ shop:D

[Utemad]

I saw you say WD type oil but thought why would you spray an oil like that? If you say it works though I'll try it out tomorrow. I guess it is more of the propellant that would be getting sucked in anyway.

[Blknight.aus]

the spuds are just for sealing up the exhaust system so that the valves that are "on the rock" dont let lots of air past.

[camel_landy]

My 1994 3.9 V8 Disco has a whistle. It has been doing it for months but I cannot pinpoint it.


You could always just try to teach it the words instead.... :angel:


Coat please.

[Blknight.aus]

areo start is hihgly flamable and only explosive (and then thats really marginal) when under pressure.

[Utemad]

I sprayed around everywhere I could think of with WD-40 and nothing happened.
I might give the vacuum cleaner a run tomorrow.

[Blknight.aus]

if yo ucouldnt find it in the engine bay...

its down to 1 of 2 places..

1. the brake booster

2. some aircons (never pulled one out of a rover in its entirity, not a fridgey and I dont do "cosmetics" have vacume operated flap valves If youve got them maybe its one of those?...

[Utemad]

It's definately coming from on top of the motor somewhere. You can replicate it in very short bursts by revving the motor up and letting it go back to idle. However by the time you start poking in the vacuum lines the whistle has stopped. Vacuum cleaner time I think.

[LoadedDisco]

the spuds are just for sealing up the exhaust system so that the valves that are "on the rock" dont let lots of air past.

Blknight's idea is correct and you should give it ago before going to expense.
The air flow he is talking about will if a leak is present in the exhaust system will let out a low whistle where your leak is if it is in that system area.

I would spray again soapy water around all the seals on a cold started to see if a leak can be detected. If not then hit the vacuum.

[LoadedDisco]

I sprayed around everywhere I could think of with WD-40 and nothing happened.
I might give the vacuum cleaner a run tomorrow.

WD-40 will not produce bubbles to show a leak and is also not the best product to spray on the motor as it disperses grease. WD – 40 is no good around greased products.
It is only good for certain applications.
Try Inox it promotes grease and doesn’t try and spray it away.
You can also get Inox with Lanolin best for salt-water applications and wont affect rubber hoses or fittings.

[KiwiSteve]

Hi Ihad a similar sound chased it for weeks turned out to be the water pump on the way out changed it no more noise. best of luck.
KiwiSteve.

[Utemad]

Hope it isn't the water pump. It was replaced about 6 months ago. Just before I bought the car :)

The whistle is definately coming from on top of the motor. In the V area where all those little vacuum lines hide out.

I was going to do the soapy water spray today but got carried away hooking up an air line to the towbar so I don't have to open the bonnet to pump my tyres up anymore.

[Pedro_The_Swift]

that propane torch is a cluey idea!:D

[Utemad]

Problem fixed :)

I did the soap trick but did not find the leak. So since I could hear that it was coming from the driver's side of the plenum chamber and that the hoses were in good order I just changed all the hose clamps for stainless steel worm drive units and hoped for a better seal. It worked so I am having to get used to driving my V8 without the imitation turbo :D Can't believe I drove it like that for months when it was such a simple fix.

[Utemad]

Well the fix I mentioned above turned out to be temporary. It had been whistling for a while again before last week when I replaced the intake manifold gasket as part of another job and discovered that three of the intake manifold bolts were finger tight. The middle three on the drivers side of the motor. Right below where I thought the leak was.

I am assuming this is where the whistle was coming from but of course to get at this your need to remove and therefore reseal the plenum chamber so it could have come from there also.

I tried the vacuum cleaner trick a while ago and it didn't work for me.

[ozscott]

Did you beat it mate - mine has the same thing - at low idle and getting louder!!! As soon as the revs raise to even 1000rpm on the throttle it goes, so my bet is bad vac leak

[Utemad]

The whistle has gone completely. It never came back after I did the work that I spoke of in the post above yours.

So I was very happy with that as it annoyed the crap out of me.

[Jim621]

I have a similar whistle, but due to a different issue i think.

I have a 98 V8 Auto, and i get a whistle sound through the intake when i accelerate lightly. The sounds has been there since i bought the car 6 months ago, and i have since put a snokle on so the sounds is now emitted from the snorkle intake.

I only get the noise when accelerating between 1200 and ~1500 rpm, which is quite annoying when im 4wding.

Do you think its a vacuum leak? The car runs very well, and the noise doesnt affect the engine at all as far as i can tell....

Its more an annoyance.

Anyone got an idea of what it could be?

Cheers, Steve

[milld]

congratz :)