Anyone know what this is?

[hokie7]

i looked under my 71 bronco today to try and find out what was causing a rattling sound. on top of the d-20 t-case i saw a little cylinder going up towards floor about an inch high. it was topped off with a metal cap (the whole thing looked like a mushroom). the cap was loose and was causing the annoying rattle as higher speeds. what is this for? can i just use some silicone and keep it from rattling? thanks, i know this is a shot in the dark

 

[Bear1911]

I think that is a vent for the TC.

 

[hokie7]

well i did some research and now know that it is the vent for teh t-case. but is it supposed to be loose and rattle? the noise gets progressively louder as i drive faster and it is audible above the engine and road noise.

 

[72_EB]

Yep, it is indeed the vent. It does rattle and is loose on there.
You should stick a vent on hose and run it up the firewall. Todd Z. did a tech article on it I believe. I'll try and find it now.

 

[72_EB]

http://www.azbronco.org/tech10.htm


Here ya go. God, I love google!

 

[hokie7]

being that i dont take me bronco off-road that much would it be okay to just silicone one side of the vent cap to stop it from rattling. i dont know, maybe i am wrong but mine just seems to rattle alot more than others, i mean it can be heard very clearly when going only about 25 and it didnt seem to do it that loud when i first got it

 

[Broncobowsher]

IF you silicone the vent shut, it will find a new vent. Typically venting the gear oil out the seals. Do not seal off the vent, it needs to breath both ways.

Secondary, I can't believe that your bronco would be quiet enough to be able to hear that vent rattle. Broncos are not that quiet. The rattle you are hearing has got to be something else.