Odd whining noise

[Jackp]

First time posting, so hello!
So recently purchased a 1hdt 80 series which i think (after reading previous posts on here) was owned by a chap who posted on here.

Essentially the truck has a whine that starts at about 40 but goes instantly when you let off the throttle, and comes back instantly when re applied, more throttle = more whine effectively. If i have bought it out the person who was posting on here, its had a recent from diff replacement/rebuild? So reluctant to think that.
Possible transfer case?
Now this might sound crazy, but what about the drive belts? It doesn’t sound like a traditional belt squeal but one of the 2 has snapped prior to me buying it ( found the remains underneath) and the voltmeter on dash doesn't seem to get much past halfway? Not sure how accurate the gauges are mind, will be throwing a new pair of belts on regardless, and checking pulleys. And will try see if the noise will go if i coast in neutral and stuff! But yeah any advice id be really grateful! Thanks! Sorry for the long first post!

 

[Ben Stratford]

I have a whine too when I go over 50. But it stops when she isn’t in the car with me!

 

[AndycruiserguyLomas]

I have a whine too when I go over 50. But it stops when she isn’t in the car with me!

Someone had to go there

 

[IRLGW]

Is the air intake leaking anywhere from the filter housing to the manifold?
Is the Turbo worn
Quite possibly a diff or gearbox bearing. Obviously check diff have oil..

 

[Shayne]

A/C belt top pulley , can't remember exactly but i think its free spinning and I took mine off to grease it .

 

[frank rabbets]

I had a VERY strange whine, more like a whistle. Turned out to be a warped EGR aluminium manifold . The metal gasket was acting like a reed. A quick file back to flat sorted that.

 

[Ciderman]

I could be waaaaay off on this, but years ago i had a beautiful 60 series that had a whine when in any gear and presented itself mostly around 50 ish mph.
Turned out to be a worn idler shaft in the transfer box, no dramas and i lived with it.
The idler ran on needle bearings on a huge fixed shaft.
I did buy the replacement bearings and seals to do a full refurb but sold it before i had the chance to drop the transfer out and open it up.

It was only when loaded, and when on the over-run, it was quiet.

It never got worse.

 

[Jackp]

Is the air intake leaking anywhere from the filter housing to the manifold?
Is the Turbo worn
Quite possibly a diff or gearbox bearing. Obviously check diff have oil..

Not that i can see no,
Diff oils okay

 

[Jackp]

A/C belt top pulley , can't remember exactly but i think its free spinning and I took mine off to grease it .

Interestingly i gave that very same pulley a wiggle earlier (belt on) and a fair amount of play in that bearing, will run it without the AC belt and see if it improves

 

[Towpack]

If it only whines under load and disappears on overun it's unlikely to be engine belts IMO. Belt driven ancillaries, like alternator and AC (when switched on) etc are under load all the time irrespective of road speed or throttle position. In the case of the alternator the load will increase with current draw.
Does it always start at 40 in any gear? If so it has to be final drive related, ie, transfer box, diffs or maybe front CV's? Just my 2p.

 

[frank rabbets]

My whine was throttle dependant, not road speed or gear dependant. Have a look at the egr valves. You might see a small gap between one and its ally flange. No idea why my manifold suddenly warped.

 

[Jackp]

If it only whines under load and disappears on overun it's unlikely to be engine belts IMO. Belt driven ancillaries, like alternator and AC (when switched on) etc are under load all the time irrespective of road speed or throttle position. In the case of the alternator the load will increase with current draw.
Does it always start at 40 in any gear? If so it has to be final drive related, ie, transfer box, diffs or maybe front CV's? Just my 2p.

Yeah i hear you, starts getting noticeable at 40, goes away around 60 ish, any gear yes, although knock it into neutral at that speed and it does get quieter

 

[Towpack]

Knocking it into neutral obviously unloads the transmission, maybe a slight reverse load from the wheels driving the props and boxes but nothing like that reached with engine braking.

 

[Shayne]

Did anyone mention exhaust yet ?

Its throttle dependant and a whistle is a pipe with a hole in it .

 

[Jackp]

Did anyone mention exhaust yet ?

Its throttle dependant and a whistle is a pipe with a hole in it .

Gonna check all the egr and exhaust pipework over the weekend

 

[thelal]

I just picked up a small bluetooth microphone for my phone and was going to attach a magnet to it so can place under the truck "finding noises". Was trying to diagnose a noise I was getting but got it sorted (rear diff & pinion bearing).
So will try it out in next few weeks and see how it goes.
Was about $8 on ebay/China

Saves trying to get one of the kids leaning out of the windows/doors trying to figure out where the noise is