700R4 Spews fluid when in reverse.

[throttle out]

This trans has always had leaks since I took ownership of it. Last winter I did an LS swap and decided to keep the 700R4 until I had the money for a Monster Transmission. I replaced the leaking seals, but seemingly out of the blue it started leaking when in reverse gear. Seams to be coming from the vent on the top of the trans, and I have confirmed that it is indeed only happening in reverse gear. This is otherwise a good transmission, forward gears shift well even with the extra LS power going through it. Anybody got any clue here?
Everyone I've mentioned this problem to can't seem to come up with anything logical.

 

[HotRodPC]

And it's not overfilled with fluid right? I assume if so, it would have quit this problem by now.

So the only other logical issue it could be is a clogged port or hung up valve in the valve body. I've only heard of this 1 other time and IIRC, the guy swapped out the valve body and it corrected the problem. That guy is now deceased so I can't even ask him now to be sure. Sorry !!! RIP Mr Harry G !!!

 

[throttle out]

HotRod, thanks man.
Yes, fluid levels are good, and the TV cable is adjusted well. It is otherwise a good transmission, If I could pop a $200 valve body in it and be off an running again, it could be worth it. I was hoping it would get me buy for a while to allow me to restore the bank account if you know what I mean. I'm still chasing brake issues and the 12 bolt needs a complete overhaul.

 

[throttle out]

Looks like the case is cracked. She's toast.

 

[HotRodPC]

Ahhh ****. That is the other thing that causes this problem. I sure wouldn't have thought this would be one of those.

Where is the crack at? And is that where the fluid is spewing from or is it spewing from the vent pipe?

 

[HotRodPC]

And don't scrap that transmission. You may very well need those hard parts. Maybe you can find a burnt up 700r4 and transfer the guts, or if you find a cheap non working trans that you have rebuilt, you might need some of the hard parts for your build.

Is it the original transmission to the truck? If so then it's a 1987 model case? Be sure to find an 87 - 93 core. Don't do an 86 or earlier.

 

[87scotty]

Are the cases not weldable?

 

[HotRodPC]

Sure they are, but if he's spewing fluid only in Reverse, I have a feeling this crack goes all the way to the internals. So if you weld it on the outside, chances are the puddle will clog the passage on the inside where it's broke and the repair is made. This isn't going to be a crack in the bellhousing or a ear broke off the case.

At least that's my thoughts on this one. He hasn't said where the crack is yet.

 

[throttle out]

Crack is at the upper rear portion of the trans and the fluid is coming from it. When the reverse piston is thrown fluid is able to seep past the crack.

THIS HAPPENED BECAUSE I DO NOT HAVE A "TORQUE ARM" GOING FROM THE T-CASE TO THE BELL HOUSING OF THE TRANS!!
My truck didn't have one when I bought it and never knew that it should be there, it significance is real. The trans is weldable indeed but I did not want the worry. The trans is otherwise a good one and held the extra power of the LS motor. It and the 208 will be for sale as soon as its out. Any little bit helps recoup funds.

I'm having a good friend build me a 4L65E as we speak, going with a brute sunshell and stage 2 kit!! Working to gather the parts for the swap and I have a NP241c passenger drop out of a 91 K5 as well. Should be a huge improvement!!
Now just gotta decide weather to rebuild my 12 bolt rear or replace it all together. Besides paint & body and interior updates/finishing my trucks mechanicals and driveline will be damn near 100%!! Poor truck had a HARD life before I got my hands on it, feels good to breath new life into it even if the pocket book disagrees lol!

Thanks for the help fellas!

Pictrures of the torque arm/rod

 

[Rusty Nail]

Are the cases not weldable?

Everything is J-B weldable.
LoL!

 

[HotRodPC]

Crack is at the upper rear portion of the trans and the fluid is coming from it. When the reverse piston is thrown fluid is able to seep past the crack.

THIS HAPPENED BECAUSE I DO NOT HAVE A "TORQUE ARM" GOING FROM THE T-CASE TO THE BELL HOUSING OF THE TRANS!!
My truck didn't have one when I bought it and never knew that it should be there, it significance is real. The trans is weldable indeed but I did not want the worry. The trans is otherwise a good one and held the extra power of the LS motor. It and the 208 will be for sale as soon as its out. Any little bit helps recoup funds.

I'm having a good friend build me a 4L65E as we speak, going with a brute sunshell and stage 2 kit!! Working to gather the parts for the swap and I have a NP241c passenger drop out of a 91 K5 as well. Should be a huge improvement!!
Now just gotta decide weather to rebuild my 12 bolt rear or replace it all together. Besides paint & body and interior updates/finishing my trucks mechanicals and driveline will be damn near 100%!! Poor truck had a HARD life before I got my hands on it, feels good to breath new life into it even if the pocket book disagrees lol!

Thanks for the help fellas!

Pictrures of the torque arm/rod

Dammit, you're to far away. I have a good case that needs a rebuild. I coulda swapped all your internals into this case I have and have a working transmission. So you'll have a computer controlled transmission now. That's all fine since you're running an LS ECM controlled engine already. Should be a good combo.

 

[mduran3596]

I just rebuilt my 1988 700R4 and runs great but when it is shifted into reverse it leaks fluid from same crack in the case. The reverse clutch piston is there and pushes the fluid through a hairline crack. This is a common problem with these especially if overloaded or abused. It can be welded but there’s a good chance of distortion of the reverse piston bore. So basically the case is trash. One good thing is it will only take about 3 hours to swap out the guts to another case.

 

[Dmack]

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