High pitched speed related noise

[hijimhere]

I had a minor in/out noise which has developed. Was about 50 ish mph - now coming in about 35 fairly quiet to start as speed builds the volume increases. I have had the diff levels check, front needed a small top up which I agreed with the tech was very unlikely to make any difference!
We were right it didn't make any difference.

The noise is similar to the now long gone olden days like turbo whistle as the turbo spools up. But it is not there when stationary holding revs up down then up again. It does appear to me to be rolling speed related rather than any auto gear position when in motion or when stationary in relation to engine RPM.

Not sure if I have a transfer box but it is beginning to look like its diff related. Would you folks agree or am I missing something.

The one recent occurrence just before this started I had no history of having to top up the oil over a 2 year period - checked on average monthly or if I was going on long journey. I was doing a routine level check and the oil was almost one the minimum mark. There is no patch on the drive and no sign of blue exhaust smoke.

[the laird]

Sounds like it could be a wheel bearing possibly does the noise alter if you sway the vehicle from side to side ,make sure it's safe to do so if you have not done this already.

[rita]

I had a minor in/out noise which has developed. Was about 50 ish mph - now coming in about 35 fairly quiet to start as speed builds the volume increases. I have had the diff levels check, front needed a small top up which I agreed with the tech was very unlikely to make any difference!
We were right it didn't make any difference.

The noise is similar to the now long gone olden days like turbo whistle as the turbo spools up. But it is not there when stationary holding revs up down then up again. It does appear to me to be rolling speed related rather than any auto gear position when in motion or when stationary in relation to engine RPM.

Not sure if I have a transfer box but it is beginning to look like its diff related. Would you folks agree or am I missing something.

The one recent occurrence just before this started I had no history of having to top up the oil over a 2 year period - checked on average monthly or if I was going on long journey. I was doing a routine level check and the oil was almost one the minimum mark. There is no patch on the drive and no sign of blue exhaust smoke.

Yes the vehicle has a transfer box, it would be worthwhile checking the oil level in the box as this could be the source of the noise.

Not saying this is the problem..the box uses a chain drive that can cause noise problems when a bit dry.


Good Luck.

[adscatt]

Have you checked the brake pads, particularly the inside pad. Not sure of Bongo's but Mazda's of this era had metal tabs on the pad clips which would contact the disc when pads wore down creating a high pitched noise which was speed proportional.

Is it louder front/rear, left or right?

[hijimhere]

Thanks guys - invaluable stuff - it might be brake related so did a few tests to rule that out, definitely NOT a metallic pad noise thank goodness. Did the maneuvering to check possible wheel bearing but not that. The point about the rattling is interesting as my next set of questions was going to ask if there is anything chain driven as I have had an idle speed noise that is similar to a loose timing chain/idler gear rattle. My bet is the transfer box. Is the chain at all adjustable? What oil is in the transfer box? Thanks for your very help full analysis. I don't have access to a ramp so back to the guy who topped up the diff for me tomorrow.

[philpdr]

Low fluid in power steering?sometimes this can make the pump whine.

[hijimhere]

Got the oil type SAE 90 same as diffs

[rita]

Might be worthwhile checking the speed sensor on the TB while you are there.(not saying that its the problem but they can get a bit dry if the oil level is very low).

Good Luck.

[hijimhere]

The transfer box took "couple of cup fulls" being old school I knew what was meant - has quietened the noise considerably with the added bonus of also making the chain "chatter" a lot quieter as well - its there but only just.

I put an enquiry to our neighbours across the pond for a new transfer box chain, an autobox cooling kit and a gearbox manual. The quote was as follows.

cooler kit (PTK-1H) = $63.50
t-case chain (10-111) = $421.36
ATSG CDROM rebuild manual (RE4R01A) = $25

Add in the $80 shipping fee and there you have it - I doubt very much I will be buying a chain but at some point I will go for the cooling kit & gearbox manual (for an off vehicle refurb project). Happy to add to the order if anyone wants anything.

The company is Transmission Exchange Co of Oregon - they clearly have an expertise on automatics.

[helen&tony]

Hi
Don't forget import duty, handling charges and tax. I believe that the tax is also on the postal charges. That'll be $168.5 + 20%...not including handling plus tax.....I have a transmission cooler on mine, P.M. me for the U.K. supplier!...it's probably cheaper!
Cheers
Helen

[rita]

You need to find out, where, how, and why it Drank "couple of cup fulls" of oil.

[hijimhere]

sure do Rita - I am on it!

[Gasy]

I'd be interested in the uk supplier of transmission cooler kits pls
Another round of PMs on the way

[the laird]

Make sure if no visible signs of leaks that the breather/s ain't blocked up

[hijimhere]

Thanks Laird - I have just been looking at Lush schematics for the transfer box - can't see the breather showing - is it easy to access on the vehicle?