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I have a 86 F350 with a 6.9L, 4-speed t19 transmission and a BW 1345 transfer-case.
Once everything warms up it starts making a weird whine that changes with speed and disappears under 20km/hr. kinda sounds like a whoop, whoop, whoop that gets faster the faster you go.
When pressing down the clutch pedal the noise disappears.
Noise happens in 4 and 2 wheel drive.
All fluids are new and full
All new u-joints
clutch has under 10,000 miles
So today finally took it into shop and put on a lift. Started the truck and the noise started while on the lift. The sound travels through the entire drivetrain, but is loudest at the transfer-case.
Anybody experience this noise before?
And how easy is it to rebuild the t-case? as I assume the chain is stretched/worn as it is the only thing that moves in 2 and 4 wheel drive if I am not mistaken. Or is it easier to just replace the t-case with a reman or used one.
Sure sounds like a stretched chain, but wouldn't hurt to pop the t-case open and have a look inside, there not hard to take apart providing the bolts aren't corroded on.
Whats the mileage on it? Must be high, or abused at some point if low.
It only has 92,000km and in another 8000 I will be back at 0. So if my math is correct I will have a new truck Its hard to say how many, it is in pretty good shape except for this.
It was definitely abused, when I changed the oil on it, a very thick and burnt gear oil came out. I replaced it with Royal Purple ATF
Did you put ATF in the transmission as well? Those trannies only take gear oil, or I heard some on here put motor oil in them. ATF is correct only for the transfer case, or the M5OD (F150 transmission) or the ZF5.
It is possible since it had gear oil in the t-case that at the long run, it might have damaged or changed bearing clearances so now putting thin oil back in it will give you noises. Drain it and try new gear oil in it, if it goes quiet, run it for a while like that, till you find a spare t-case to rebuilt and have ready for whatever that one goes out.
Drained the transfer case and this is what I found
4 month and 2000km old Royal Purpal synthetic ATF
So I put some 75w140 synthetic in it because thats all I had in the shed. Drove into town and no annoying noise. Actually the truck seems to drive quite a bit quieter now.
Now it is time to start looking for a spare t-case.
At least it gives you extra driving time on the truck before putting it out of service. It might even last for a long time as is with the thicker oil, although I wouldn't chance it forever.
At least it gives you extra driving time on the truck before putting it out of service. It might even last for a long time as is with the thicker oil, although I wouldn't chance it forever.
Well it didn't last very long, about 300km and the noise is even worse. Drained the oil and it was already burnt and full of glitter.
So after phoning a dozen salvage yards I finally found one with around 250,000km out of a 85'. I guess they are a little old and no one keeps them around. Changed the front universal yoke to match my drive shaft and in she went.
Didn't know the old girl could be so quite, except now I am hearing all sorts of new squeaks and rattles that was drowned out by the T-case.
Its hard to say how many, it is in pretty good shape except for this. 
