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Discussion Starter #1
Recently acquired a nice 75k, 1 owner 4.6 auto.
Just given it a full service, all oils etc and it runs like a dream, but.....
I have a not too noisy whine under load that reduces on slight throttle and disappears when throttling off.
Whine stays constant and doesn’t change when gears change.
Not from diffs but sounds as if from auto box or transfer box.
Must be a final drive bearing.
Any ideas? Is this a common problem?
 

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Whining diffs are common, try dropping a propshaft and seeing if it goes away. You can run short distances with only one prop in place but drive for any length of time and you will cause the viscous coupling in the transfer case to seize. When you remove the rear prop, make sure you put a couple of nuts on to hold the transmission brake drum in place or it will try to make a bid for freedom from under the car. If the whine isn't there with the front prop removed, it's the front diff, if it goes away with the rear prop removed, it's the rear.
 
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Discussion Starter #3
Thanks for that.
I didn’t think it came from one of the axles but of course it is hard to tell from the driver seat! I am putting it back on the ramp tomorrow or Friday to remove the springs and fit the air springs and connect up. Once this is sorted I will get back onto the whine!
 

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+1 diff.... I replaced my rear with similar whining characteristics to yours. But there was also a clunk when I changed direction. I couldn't decide between the diff and tfr box (as you say, impossible to tell) but went for the diff first since it was cheaper/ easier...Turned out to be a good guess, but GilbertDs method wd have helped me
 

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Discussion Starter #5
Thanks for the replies.
By process of elimination, (unfortunately the second try!) It is the front differential. Noise gone with front prop removed.
Disappointing that this is whining with only 78K genuine miles on the clock. I also have a Mercedes ML 320 which had done 90,000 when I bought it and has now nearly 150,000 on the clock. Not the slightest wine or moan from any component. No wonder British cars get a bad name.

Here is a question, does anyone have a good condition front differential for a P 38?
 

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Ashcroft Transmissions Ashcroft Transmissions rebuilt with a warranty. They are often noisy and although the mileage is low, you don't know how well it has been maintained. When you changed the oil was there any shiny bits in it and what did you put in it? I put Millers synthetic 75W-90 in my rear axle and a whine appeared. Drained it and filled with ordinary 75W-90 and it went quiet again.
 

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Discussion Starter #7
Thanks for that, I have used them some years ago.
Regarding changing the oil. It was whining slightly when I got the car, I changed the oil for a medium quality brand, Titan I believe from my local motor factor and the whine was exactly the same.
My local Land Rover independent, InsideOut 4x4 are closed till Monday but he has messaged me and says he has at least one P38 differential in stock. I know him well and will trust his judgement if he says it is a good one! We shall see.
I shall carry on stripping off the springs and treating a bit of surface rust around the chassis while I wait!
 

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Make sure you get a front diff. Although a rear will fit and many claim they are interchangeable, the gears are cut in the opposite direction so will whine. It will work, but will be noisy.
 
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