I am looking for input on what could be the cause of 700r4 failing. (I will start by saying I know nothing about automatic transmissions) I have a jeep with a TBI350/700r4 combo and the tranny stopped working this weekend. I was drive in first gear driving up a hill and the engine rev’d but it lost all drive. None of the gears, forward or rev, worked. It had never slipped or acted strange before this. It did not hear any bang and breaking sound when this happened but it did make a clunking sound about every revolution of the motor right after it stopped working. It sounded like it was coming from the front area of the tranny but I could not pinpoint it any more than that. No fluid leaking or any visible signs of damage from the outside. Any ideas?

Sounds like the pump blew out on you. Time for a complete rebuild. When a pump fails it sends metal thoughout including the torque convertor. Be sure to flush the cooler out really well as to not take out the new trans.

If it is the pump is it possible to flush and reuse my valve body in another tranny or would it be contaminated beyond reusing?

It could also be that the torque converter clutch grenaded. When that happens it will usually crawl along very slowly if you rev the engine with it in gear. Either way you are most likely looking at a rebuild since the tranny will be full of metal chunks.

I talked to Keith at Susanville Transmission and seems to think converter or pump. It was nice actually talking to some who will take the time to explain things. :smokin: I will pull it out and see what's happening in there.

There are upgrades for both the pump and the converter. Really just about every other part in the trans too. I will not get too deep into 700R4's because it is a touchy subject on here. Just make sure all your hard parts are made in the USA. I had some aftermarket planetaries that were supposed to be an upgrade that ate themselves spreading bearing and spacer pieces throughout the transmission. So buy good parts to begin with and upgrade as much of the transmission to 4L65E (Corvette) hard parts as you can.

Before yanking the trans out, do a pressure test real quick to aid in diagnosis. There is a small 1/8" NPT plug above the shifter on the case. Pop in a gauge and check pressure, should be at least 50 psi at idle and raise with the throttle. If no pressure, than it most likely is pump failure. If you have pressure and no go, then you may have a converter that is no good.

I talked to Keith at Susanville Transmission and seems to think converter or pump. It was nice actually talking to some who will take the time to explain things. :smokin: I will pull it out and see what's happening in there.

yeah, you dont want us helping you... take it to a shop. we arent paid to be nice to you.

yeah, you dont want us helping you... take it to a shop. we arent paid to be nice to you.

Paid or not some vendors are assholes.....Keith took the time and I appreciated it. You forgot to add how much you hate the 700. :flipoff2:

I was trying to omit that.

I built the 700 in my camaro. They are good transmissions when built properly, but they have some inherent problems due to being a primarily 80's design (my opinion anyways). Some weak spots to consider are:

The front pump bushing has a tendency to push out when the transmission is used in heavy duty or high performance applications. There's a neat trick to fix this, I'll see if I can find the picture of mine.

The sunshell on them is weak around the hub. You can buy either a hardened GM shell or I went with a BEAST Sun Shell in mine.

Use the 4L60E band, its a touch wider and provides better holding power.

Use Trans-Go shift kits, forget those B&M kits, all they do is make it shift hard, not make it shift well.

Pump rings are weak, Trans-Go has a kit to fix this problem also.

Use the corvette 2-4 servo parts, but be leery of the aftermarket ones that claim to have more hold than the vette parts, you can get too much of a good thing, especially with big tires.

A trick we used was taking out the wafle (way-ful) steel in the clutch packs and replacing with a standard steel to make up the difference. Firms up shifts a little.

edit: I didn't take any pictures of how it was fixed. What you do is:
Drill 3 holes equally spaced in the rear(inner) edge of the bushing bore. Install the bushing into the housing and take a punch and bend "ears" (or peen, depending on your vernacular) the edge of the bushing into these holes. This will prevent forward movement of the bushing as well as spinning of the bushing when the housing heats up.

Did you accidently knock the t-case in neutral??

Did you accidently knock the t-case in neutral??

:laughing:

edit: I didn't take any pictures of how it was fixed. What you do is:
Drill 3 holes equally spaced in the rear(inner) edge of the bushing bore. Install the bushing into the housing and take a punch and bend "ears" (or peen, depending on your vernacular) the edge of the bushing into these holes. This will prevent forward movement of the bushing as well as spinning of the bushing when the housing heats up.
Isn't this method called "staking"?

Before yanking the trans out, do a pressure test real quick to aid in diagnosis. There is a small 1/8" NPT plug above the shifter on the case. Pop in a gauge and check pressure, should be at least 50 psi at idle and raise with the throttle. If no pressure, than it most likely is pump failure. If you have pressure and no go, then you may have a converter that is no good.

3rd scenario=convertor hub splines stripped out/hub busted inside convertor=no line pressure.

Update:

With the engine running and I go to put it into park it grinds without actually going into park. Something is still spinning in there.

I dropped the pan and it did have a little super fine slug like stuff in the bottom of it.

I will try the pressure test this weekend.

Now that the pan is off. Put it in park and make sure you have the linkage fully engaged. Then try and rock/move the vehicle-if it moves you have either the transfer case disengaged or something busted in it.

lol, its the transfer case...

3rd scenario=convertor hub splines stripped out/hub busted inside convertor=no line pressure.


Well you confused me.. :shaking:

You have stator splines and input splines, neither of which if stripped would cause the pump to not function. Now if the pump drive tangs were broke, then it would have no pressure, which would be what I said, pump failure.

lol, its the transfer case...


My thoughts exactly.....If only we had the noise infor from the start.


Do you have a 208 tcase Jethro? Have you tried shifting it to different gears?

Atlas 4.3

I tried all gear combos.

Isn't this method called "staking"?


Yeah, that too.... :D

I was trying to omit that.

Is that some "niceness" coming from you grump? LOL. I am not a fan of the 700R/4L60/E either vs a TH400...but they can be made ($$) much stronger.

Did you accidently knock the t-case in neutral??

Damn... LMAO... :D

Is that some "niceness" coming from you grump? LOL. I am not a fan of the 700R/4L60/E either vs a TH400...but they can be made ($$) much stronger.



stronger than the stock version of the 700r4, but not as strong as a 400.

No to jump on the bandwagon here.

But there are sooo many posts about 700s blowing up or failing, that the standard answer should be:
Toss it and upgrade to a 4L80E or TH400.:D

Just my .02 cents.

I am looking at all options. :D

I need to look around and see what it will take to get a 400 to mate to my Atlas.

I am looking at all options. :D

I need to look around and see what it will take to get a 400 to mate to my Atlas.

Time and money well spent. I think you'll be much happier with a TH400.

I'd stick with the 700 for a driver/wheeler.

For a buggy/trailer queen, a 400 with reverse valvebody for the quick 1 to R shifts, they handle it much better than 700/350. (but personally, I run a 700/4l60e in everything I wheel)

700 and 400 are same length basically, so that's a wash. 700 has lower first and OD, which kicks ass for an all purpose rig.

I need some more input. I pulled the tranny and the TC hub is spinning free from the rest of the converter and rattles around if I shake the converter. Broken TC? Also I can not turn the pump....seized pump?

Tarnation more troubles. Pump jammed probably or busted up. More $$.

Post up some pics of what you are talking about. I am thinking by hub you are talking about the stator in the converter, and yes it should spin, and converters do have some rattle noise to them when shook.

And by turning the pump, are you turning the stator support splines that are around the input shaft? If so, then the stator support is supposed to not move.

PICS of what you are referring to!!!

http://www.insomnia4x4.com/albums/Rainfly/IMG_1406_001.sized.jpg

http://www.insomnia4x4.com/albums/Rainfly/IMG_1407.sized.jpg

oh, now THATS priceless....
lmfao!:laughing::laughing::laughing::laughing:

I started by saying I know nothing about autos..... :D

Let me guess...that is how it is supposed to be? :homer:

Post up some pics of what you are talking about. I am thinking by hub you are talking about the stator in the converter, and yes it should spin, and converters do have some rattle noise to them when shook.

And by turning the pump, are you turning the stator support splines that are around the input shaft? If so, then the stator support is supposed to not move.

PICS of what you are referring to!!!


Why do I feel like this was a setup...:laughing:


I understand it now.....thx

Jethro yer missing an o-ring from the groove on the end of the turbine shaft. That needs to be there to get lockup from the torque convertor. Really not an issue with off road use.