Hello, we are the 501(c)(3) non-profit Military Mobility, which provides suicide prevention and resiliency training to veterans in need. We use the rugged geographic landscape as a medium for the personnel and professional challenges we face in life and a fleet of 4WD vehicles to literally navigate and overcome obstacles. This provides massive opportunity for positive transformational growth.

Recently, we purchased sight unseen (never again!) a supposed beautifully restored 1997 Defender 300tdi. Previous owner said gear box, transfer box, and axles were refurbished recently. Sure enough the paint and interior is impeccable but it makes a horrible high pitched whining noise while driving. It’s sadly our problem now. Here are the troubleshooting bullet points and I’ve attached a link to several short videos of a test drive and what the drained fluids look like.

-whine only present when foot is actively on the accelerator.
-no whine when off gas pedal, coasting, braking, or in neutral.
-whine present in both high and low transfer case, including while locked.
-whine present mainly in 3rd, 4th, and 5th gear. Somewhat audible in 1st and 2nd but only at very high RPM’s.
-whine seems to get higher pitched the faster the vehicle is going (see test drive video)
-changed fluids in gear box (ATF), transfer box, front & rear diff (EP 80/90). Nasty stuff came out (see videos). No change.
-removed front and rear driveshafts one at a time, whining noise still present.
-serpentine belts and pulleys are in good condition and don't appear to be slipping


*We are deeply appreciative of your experience and assistance. This is our first Defender and we are based in rural Wyoming, USA. We do have relationships with some Land Rover specialty shops however these are 10 and 20 hour drives away.

Welcome to landyzone fireplace.

It looks like other than the rear axle other units have been running on incorrect oils or just have not been changed. The transfer box and axles may be ok given new EP80/90 oil. The gearbox however runs an internal pump system using Automatic transmission fluid [ the red stuff over here] Sad to say given filing fluff on plug damage is likely already done.
Hate it that some barsteward would sell it to a charity for those who served.

On the g/box oil - some of the later R380's on the 300 tdi's were specked to not use ATF - the gbox serial number should be sufficient to find the specked oil by LR

having said that mine is a July 97 model and is specked for ATF

The whine exactly as mentioned in post one was something I had on an overhauled transfer box by the best in saffa land

turned out to be the bearing on the front output
fixed under warranty from the company and still good 500 k later

The R380 gearbox likes something called MTF 94 - I'm not sure what this would be sold as in the USA, but it's a bit like ATF but sold as suitable for manual gearboxes, hence the letter 'M'. It's supposed to be OK for all versions of the R380. Yes, EP 80/90 is usually fine for axles and transfer boxes because they have big meat grinder gears and no fancy synchromesh mechanism. Also of interest is the fact that many people claim to have cut down transmission noise with Difflock Evolution oils https://www.difflock.com/oilsandadditives/oils/gearbox-oil A bit pricey, but some say they're worth it. I tried them once and went back to the cheaper stuff because I couldn't tell the difference.

If it's a bearing, whilst there may be a long delay in getting Land Rover approved items out in the USA, most of the bearings are fairly standard ball or tapered roller races, so if you can measure the dimensions accurately, it should be possible to get them from any bearing shop. One thing that's very good in the US (and which I envy) is access to hardware items and tools.

Going on what @D1Nut says above may be worth running through the gears of the main box with transfer in neutral to see what it sounds like. It will not have much loading but may give a clue.
To check output shaft bearing grab prop [ wheels chocked Hand brake off ] and see if there is any side to side up down movement.

You can fit the gearbox output shaft gear on backwards it still drives butmakes a terrific whine, dont ask me how I know!

Military Mobility said:

Hello, we are the 501(c)(3) non-profit Military Mobility, which provides suicide prevention and resiliency training to veterans in need. We use the rugged geographic landscape as a medium for the personnel and professional challenges we face in life and a fleet of 4WD vehicles to literally navigate and overcome obstacles. This provides massive opportunity for positive transformational growth.
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Thats an excellent bit of chat GPT'alization.

Welcome.
Sounds like you have a bearing gone in the gearbox which needs either ATF or MTF fluid rather than std Gearbox oil.
As @tottot said the gearbox has an internal pump which can't provide enough fluid to the bearings unless it's of the right type of lubricant, normal 'oil' is to thick.
I'd agree that the damage is likely already done.

Differentials and the T'Box are more rugged. Use an EP80W90-GL4 (or GL5) and you should be good to go.

lynall said:

You can fit the gearbox output shaft gear on backwards it still drives butmakes a terrific whine, dont ask me how I know!

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Wow that is very interesting, wonder if when the PO had it "refurbished" (if this actually happened or not) they did a backwards install.

D1Nut said:

On the g/box oil - some of the later R380's on the 300 tdi's were specked to not use ATF - the gbox serial number should be sufficient to find the specked oil by LR

having said that mine is a July 97 model and is specked for ATF

The whine exactly as mentioned in post one was something I had on an overhauled transfer box by the best in saffa land

turned out to be the bearing on the front output
fixed under warranty from the company and still good 500 k later

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I replaced it with ATF but will look into this, thank you

Military Mobility said:

Wow that is very interesting, wonder if when the PO had it "refurbished" (if this actually happened or not) they did a backwards install.

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Only 6 bolts need removing to find out.

lynall said:

Only 6 bolts need removing to find out.

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Thanks for the insight, I'm going to look into how to do this; this is our first Defender and I'll be honest I wouldn't know if it was installed correctly or backwards at this point. Not sure exactly what details I'd be looking for.

Military Mobility said:

Thanks for the insight, I'm going to look into how to do this; this is our first Defender and I'll be honest I wouldn't know if it was installed correctly or backwards at this point. Not sure exactly what details I'd be looking for.

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Have a look on YouTube for LT230 rebuild. I'm sure there will be several videos covering it.