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More 4r70w Issues (same issues)

Big D

Full Member
Joined
Sep 13, 2005
Messages
222
Hey. I recently asked a question about my 4r70w with 80 miles puking all of its fluid out while coasting down the freeway. This 00 explorer trans had a full rebuild including a rebuilt stock torque converter. After pulling the trans and TC, the front trans seal fell out when I pulled the torque converter off. The seal looked brand new. The spring wasn't broke or stretched. Also, there didn't appear to be any defects. After deciding what to do next. I finally thought I would try an oem seal and add an external oil cooler plumbed in after the rad cooler. Even though the trans wasn't running warm before (180ish), i thought i would eliminate any other possibilities for the seal failure.
Well, today I was on my way home after reinstalling everything. 32 miles in my trans puked again. Just like before it happened on the freeway doing about 60. The trans was at 180 and in O/D. Before I left I made sure the fluid was at the right level. Up until this, I had been cruising at about 50 for about 20 mins. I stopped for a couple of stop signs where the trans acted perfect. Down and up shifting.
I am at a loss. The only other thing I can think of is maybe I have the wrong flexplate. I ran this flexplate behind my old 302 with a c4. The flexplate is maybe 10 years old. Or, maybe something with the torque converter. I don't know. Any ideas on where to start? As usual, thanks for the help.
 

nvrstuk

Contributor
Just a Bronco driver for over 50 yrs!
Joined
Jul 31, 2001
Messages
8,614
I'm really guessing here but since the front seal "fell out" last time, I'm guessing the same thing is bad this time.

When installing the trans you are forcing or misaligning the TC into the seal causing it to fail.

Too many words to explain here...see if you can find a YouTube video or similar that shows how to align the TC and input shaft when installing an auto so it doesn't destroy the seal...

IF you had the wrong Flex plate or the wrong seal you would have major vibration issues OR you would have leaking issues not just after 30min of driving time

Good luck
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,835
You did use a new seal, right? I hope you didn't put the one that fell out back in.

Do you have both dowel pins in place between the engine and the transmission. It is very easy to loose one. They should be in the engine, but sometimes one will stick in the bellhousing. Those two dowel pins are what precisely aligns the transmission to the engine. The bolt holes are too sloppy to keep stuff aligned alone.

That's my starter questions.
 
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Big D

Full Member
Joined
Sep 13, 2005
Messages
222
I used a new seal I bought from Ford. And both dowel pins are in place. As for the TC. I put a small amount of trans fluid on the snout of the TC and the seal before installing the TC. I didn't have any issues installing the TC. I went right in and I spun it right on doing the spinning and clicking routine. After the TC was installed I had a good inch of space between the face of the TC and the mating edge of the trans. I dont know. It seems its gotta be something internal creating too much pressure. Any thoughts on that?
 
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Big D

Full Member
Joined
Sep 13, 2005
Messages
222
Another thought. When installing the seal, it seemed to me that it didn't take much to seat it. Does anyone know anything about that. I remember thinking it seemed too easy, and very little force was required.
 

Hozr

Bronco Guru
Joined
Oct 15, 2011
Messages
1,434
Loc.
Oly, WA
You should have to drive the seal in with a hammer and drift (seal driver) or press.. It should be a VERY tight fit that requires a hammer to remove. If it comes out by hand something is incorrect.
 
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Big D

Full Member
Joined
Sep 13, 2005
Messages
222
Anyone else. Is it possible the pump is creating too much pressure. Each time my seal has blown it has happened while on the freeway. I did read on a mustang forum about guys drilling out the drain directly behind the pump seal. Any thoughts on that? Supposedly i creasing that drain opening decreases pressure on the back of the seal. I dont know. I have spent so much time and money on this trans and this project. Just trying to cover all bases.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,355
Do you know how the install was done, and by who? Any chance you have a receipt, or can find out what was used?
The reason I ask is that the adapter kit for one of the manual transmissions (the ZF maybe?) is less expensive than the 4r70 adapter because it lacks the machining for the seal in-between. Perhaps the wrong adapter was used and your seal is not fitting properly because it's not actually the proper seal for that adapter?

Just a wild-assed guess thrown out there just in case.

Where is it actually puking out the fluid? From a vent, or rear into the transfer case? Or is it in the front case behind the torque converter? If it's in the front, then obviously the thought about the adapter housing would not apply.

I've never heard of a pump producing so much pressure that it caused fluid to leak out. Much less blow a seal out completely!

So not sure yet. But keep the details coming and maybe we can narrow things down a bit.

Paul
 
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Big D

Full Member
Joined
Sep 13, 2005
Messages
222
Paul, fluid is being forced out behind the front seal at the torque converter. Twice now within 114 miles. It was a local shop who did the full rebuild with the 4r AA kit. Thanks
 

nvrstuk

Contributor
Just a Bronco driver for over 50 yrs!
Joined
Jul 31, 2001
Messages
8,614
Broncobowsher and others on here would know for sure but there are ports on the side of the 4r70W that you can read internal working pressures. I've done this but it's been 8 years!

I would have to look up which port would tell you what that pressure port is for but other than a mechanical failure with the seal this might be a good direction although I've never heard of the pump making so much pressure it blows a seal out.
 

tirewater

Contributor
Sr. Member
Joined
Jan 28, 2011
Messages
1,040
Loc.
San Francisco Bay Area
Paul, fluid is being forced out behind the front seal at the torque converter. Twice now within 114 miles. It was a local shop who did the full rebuild with the 4r AA kit. Thanks

If the 4r70w is similar to the C4 - my C4 leaked out the front due to a damaged oil pump bushing.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,835
There really shouldn't be any pressure on the seal. Just a little oil drool off the front pump. Yes the convertor has a feed and return, but those seals are a bit further up. The convertor seal is like an engine front or rear main seal. This issue has nothing to do with the pressure in the passages of the transmission.

The fact the seal installs easy is a big issue. The bore in the front pump that the seal fits into is probably too large. At the rate you are having problems, and as much work as it is to change, I would put a new pump in. That will give you a fresh bore for the seal to press into a little better. I might even put a couple drops of Loctite bearing and shaft adheasive to glue that seal in place.
 
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Big D

Full Member
Joined
Sep 13, 2005
Messages
222
Thanks for all of those who have replied. Bowsher, I like the pump change out. Also, I found through a friend a Ford trans tech. Hope to find out more this weekend. I will update if I get things figured out.
 

Justafordguy

Contributor
Bronco Guru
Joined
Sep 26, 2009
Messages
6,253
I agree with Bowsher 100%. The seal should not be that loose. It is ether the wrong seal or something is wrong with the bore in the pump.
 
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