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I've got a weird noise, time to change all fluids. What do y'all suggest??

taipeichris

Bronco Guru
Joined
May 11, 2006
Messages
1,752
Hi Guys,

Over the past two weeks my 1966 has developed a deep, low pitch, whirling noise when accelerating at around 30-50 MPH whilst under load (such as driving up an incline). Its a new sound for my that I can honestly say I've not heard before and I've heard a lot of noises from my Bronco over the years.

I"m running a 302, NV3550, stock transfer case, Dana 44, 9 inch rear and 33's.

I'm thinking either a dry axle housing, dry hub grease, dry drive shafts or maybe a dry throw-out bearing??

With that being said, I'm going to change all oils, repack hubs and grease up the throw-out bearing and anything with a zert fitting. It's been a while so I'm sure the old girl could use the attention.

Also I just balanced tires, aligned it and checked tire pressure.

Questions...

1. What kind of gear oil do you suggest?

2. How many quarts do the dana 44 and 9inch rear take?

3. What kind of oil would you suggest for a NV3550?

4. Am I missing something else?

Thank you for your help and Happy Friday!
Chris:cool:
 

EPB72

Contributor
Sr. Member
Joined
Jul 13, 2019
Messages
803
Loc.
Pleasant Hill, CA
You can try putting the rear on jack stands in 2wd and and run it to try an duplicate noise and pinpoint problem area .stethescope does wonders....Also while driving and noise is present try turning steering wheel a little back and forth and listen for a change in tone this can point more towards wheel /rear axle bearing..
 

EPB72

Contributor
Sr. Member
Joined
Jul 13, 2019
Messages
803
Loc.
Pleasant Hill, CA
Also on fluid choice redline mtl is a good choice .or valvoline syncromesh fluid,or mopar syncromesh as well..
 

Hazegray

Sr. Member
Joined
Aug 10, 2004
Messages
795
My initial though is an axle bearing starting to act up, but yes, grease everything that requires it first, ujoints, CV's on driveshafts, etc. and go from there. If you still have the noise, then jack up the rear end and see if you have any up/down play in the rear axles. You can also do a visual to see if any gear oil is making it's way into the brake drum area, usually a sign a axle bearing is going out...
 

SHX669

Bronco Guru
Joined
Jan 9, 2009
Messages
1,997
The NV 3550 is a "sealed " transmission so if you can find an Allen head wrench big enough you can drain the fluid but then will have to take the shift tower off of the transmission to refill . Mopar has an expensive special oil they recommend ; I went with their recommendation and haven't had any issues . I figured why take the chance since the extra cost wasn't all that much in the scheme of things.
I've read where the NV 3550 is a noisy transmission - mine makes more than I anticipated so maybe your noise is " normal ". If you check all the above mentioned possibilities and can't find the problem then maybe it's from the transmission.
 
OP
OP
taipeichris

taipeichris

Bronco Guru
Joined
May 11, 2006
Messages
1,752
Hi Guys,

Thank you for all of the great suggestions! So far I found 4 missing or broken zert fittings, my Dana 44 cover was leaking and play in my front wheel bearings (not rear). So yep, she’s taking up my Sunday too but it’s all worth it!

Happy Sunday!
:cool:
 

Rustytruck

Bronco Guru
Joined
Feb 24, 2002
Messages
10,875
I would drive it in 4wd and hubs locked with the front shaft out and then the rear shaft out and see if you can isolate the noise. You have to pull them to evalueate them and lube them propey.
 
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