Really? My manual just says "MERCON" for the fluid specification...

Lol, as I was writing this post, I did a quick google search and found this link:
http://www.zf.com/na/content/media/u...d_Oil_List.pdf

Assuming that "DIT" in the link stands for "Direct Injection Turbo", then you are correct that they require synthetic. I'm pretty pissed that my manual doesn't show that requirement. Forgive me for doubting you.

 

Yeah, I can't hear my transmission over my engine and exhaust at any condition besides idle, and I don't even have shifter boots on.

 

Never had a zf apart before, but considering 4th is a 1:1 ratio, it's most likely not using anything on your countershaft. All other gears have to be stepped up/down thru the countershaft and would cause noise if something were wrong in that area.

 

I haven't looked at the owner's manual for a while; does it have a separate spec for the PSD? There's also a PSD supplement to the owner's manual, which may specify it. Our two trucks actually say it right on the "badge" on the tranny case.

Ah, light bulb moment! That would def. explain the not-in-fourth phenomenon.

 

I guess noone ever saw the diesel engine supplement that came with the owners manual. Almost everything drivetrainwise in the manual is gone over again in the diesel supplement book with different fluid specifications. It calls for Synthetic.

Anyway. If it's not doing it in 4th then that is direct driving straight down the main shaft. I would recommend checking the torque on the intermediate shaft bolts. I forget the spec but it's in the shop manual. If it's not that it may be one of the intermediate shaft bearings but I highly doubt it. The bearing directly behind the input shaft would be more likely but it would still do it in 4th I would think.
The first thing I would do is dump the oil and change it with mobil 1 synthetic. Look for any shavings in it.

Those two intermediate shaft bolts are on the back end of the trans on the outside. It will make noise if you run it with them loose. They have been known to loosen on their own too.

Lastly, check your shifter boot as was already said. When I rebuilt mine I replaced all of them. The fork boot, and a whole new shift boot assembly with the white insulator. It's amazing how much quieter that made it. These things are noisy. Gear rollover is not a problem. It's just a lot more noticeable with solid flywheels. Ford only did the 2 piece flywheel to shut up owners that thought they were buying a lincoln. They do that a lot and it's why noone makes a good truck anymore. Trucks make noise. Real ones do anyway.

 

You are correct. I guess I missed the tiny footnote in the diesel supplement book.

 

Mine does the same thing, very loud whinny noise except for 4th, I've been trying to figure out what it is but haven't yet, it is very loud it almost sounds like it has straight cut gears ( which it doesn't) it's in a 94 Fsd with a 7.3 idi

 

this is a 10 year old thread. If it’s an idi You may have more luck in the I idi forums