Long story short, put a new M5OD in my truck a few months ago. Just took it on the interstate for the first time since I bought it and when I got home and parked it noticed that the ENTIRE underside was coated in tranny fluid and a puddle was forming. So a massive leak to say the least.
It seems to be at the seam between the tranny and transfer case. How would I go about figuring out which one is the leaker? Which seals go out earliest in these?
1992 Bronco, 302/M5OD/BW1356
Tranny fluid leak
- hobbyturnedobsession
- Posts: 4621
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- Bronco Info: 96 c/o w/ 5.0
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Re: Tranny fluid leak
Is that a manual trans? Check your transmission and transfer case fluid level that'll tell you first off. If its the trans its a rear main leak on the trans, if its the transfer case its a front seal leak.
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- philofab
- Basura Blanca
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Re: Tranny fluid leak
You have to take the t-case off anyways to check. Make sure you check the three plugs for the shifter rails too, they are above and are more likely to leak. Replace with freeze plugs and RTV, and make sure your forks arent worn so much as the rails are pushing them out.
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- Posts: 15
- Joined: Tue Jan 25, 2011 10:17 pm
- Bronco Info: 1992 Custom. 302/5 speed/ manual 4x4 and hubs.
Re: Tranny fluid leak
The transmission is brand new and the factory style rubber plugs are actually freeze plugs.
I guess I have no choice but removing the T-case to get at the leak regardless. At least it's easy!
I guess I have no choice but removing the T-case to get at the leak regardless. At least it's easy!

- philofab
- Basura Blanca
- Posts: 5643
- Joined: Tue Dec 08, 2009 9:37 am
- Bronco Info: A pile of crap.
- Location: Bullhead, AZ
- Contact:
Re: Tranny fluid leak
When mine was rebuilt the guy didn't replace my shift forks and I pushed a freeze plug out on the 1-2 shaft. It caused a leak in pismo a few years ago. I don't trust very many rebuilders anymore.92Custom wrote:The transmission is brand new and the factory style rubber plugs are actually freeze plugs.
I guess I have no choice but removing the T-case to get at the leak regardless. At least it's easy!
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- Posts: 15
- Joined: Tue Jan 25, 2011 10:17 pm
- Bronco Info: 1992 Custom. 302/5 speed/ manual 4x4 and hubs.
Re: Tranny fluid leak
Well, my original tranny was so torn up everywhere that it was just sent in for the core charge on the new one, and I am AMAZED that it qualified as a core.philofab wrote:When mine was rebuilt the guy didn't replace my shift forks and I pushed a freeze plug out on the 1-2 shaft. It caused a leak in pismo a few years ago. I don't trust very many rebuilders anymore.92Custom wrote:The transmission is brand new and the factory style rubber plugs are actually freeze plugs.
I guess I have no choice but removing the T-case to get at the leak regardless. At least it's easy!
I'll check the plugs when I get it on a lift. I have a 12 month, unlimited mile warranty, so if I have to use it I will.