Leak on my np203 adapter Need help quick

[TJ1978]

if the input seal is BLOWN the heck out and you fill up the t-case to much yes it possibly could get back in the trans . and reg oils or gear oil in a auto is NOT good . altho some auto trans are built to run engine based oil but thats HUGE truck stuff or other equipment not out th350/400/700r4 units .

Input seal on the Trans or 203 are you referring to?

 

[sweetk30]

trans would be a output seal if it had one and they dont . they just get a adapter to trans case o-ring .

so yes input seal on t-case .

 

[TJ1978]

Ok... welp, Ill slightly under fill the 203 and see what happens when driving. My biggest fear is destroying the TH350 that I just had completely overhauled. It’s better than when it left GM.

 

[bp71k5]

If the trans doesn’t have an output seal, doesn’t the adaptor have one? I think I had one on my 205, but maybe the other dont?

 

[TJ1978]

First is the 4 screws that go into the Tranny with those special flange bolts
Second O ring on adapter 203 to TH350
Third is where the adapter bolts to the 203
Fourth: 203 output shaft to TH350

Where is the ATF getting into the Tcase? Has to be from th splines on the 203, right?

 

[TJ1978]

Is this the “hole” that is referenced where the fluid drains back after sitting awhile and probably filling up and getting into the 203

 

[bp71k5]

First is the 4 screws that go into the Tranny with those special flange bolts
Second O ring on adapter 203 to TH350
Third is where the adapter bolts to the 203
Fourth: 203 output shaft to TH350

Where is the ATF getting into the Tcase? Has to be from th splines on the 203, right?

View attachment 337536

View attachment 337537

View attachment 337538

View attachment 337539

there’s a big dent in the seal on that 4th pic. Also with all that RTV squeezed out, it’s just asking for a leak. Guessing that’s the output to the driveshaft though so probably not what’s letting fluid get into the case. Must be a bad trans output seal if it’s really getting out of the trans. Make sure all the breathers are clear.

 

[TJ1978]

That’s my spare 203 I use it for demonstration purposes. Hehe it’s not the one in my truck

 

[TJ1978]

I haven’t even put a 10ft of driving on the new transmission. It’s as fresh as can be. I fired it up once or twice to fill and make sure the gears engage.

Vent
The 203 and th350 in my truck

 

[TJ1978]

It’s life seems to be parked in my garage.

I did find this in case anyone else has this issue.
It’s has to be the adapter Oring or its not as flush as it was. ATFis getting into the 203 from the splines or the shaft seal somehow. Damn it. I’ll have to drop it to fix it...

I didn’t use any sealant on the splines... I’m sure some fluid seeped down when I pulled a few bolts to seal them up with permatex. The real problem if it is one, is the ATF getting into the 203.

https://www.pirate4x4.com/forum/gen...350-rear-seal-leak.html#/topics/534012?page=1

 

[sweetk30]

if your getting fluid threw the splines the input gear is junk . there a solid mass of metal and fluid is not to go threw them .

 

[TJ1978]

Yeah, I’ll figure it out... splines or seal on 203... either way. I put some oil in then drained it to kid of flush it out. The ATF was negligible at best.

 

[sweetk30]

input gear on a 203 or 205 or others for the most part are a blind hole . there is no way oil should be flowing between them in the male / female spline section of that coupling .

 

[TJ1978]

input gear on a 203 or 205 or others for the most part are a blind hole . there is no way oil should be flowing between them in the male / female spline section of that coupling .

Right but can this seal, arrowed in yellow go bad and allow fluid past it? Whether ATF in or 203 oil out?

 

[frankin5]

Did you put a new one on? Did you lube the seal before sliding it over the input shaft? Did you reseal the front bearing retainer that seal is in?

 

[sweetk30]

i have been saying this all along . the INPUT gear seal can be bad and let fluid in to the case . 1st post of mine in this thread and first sentence said input seal on 203 keeps them apart .

 

[sweetk30]

Did you put a new one on? Did you lube the seal before sliding it over the input shaft? Did you reseal the front bearing retainer that seal is in?

also did you note the clocking of the retainer ? there is a tear drop section to line up with a pin hole in the range box for oil drain back to the range box so it wont build up on the input seal and possible leak out.

 

[TJ1978]

I did what was told to me in that thread for the 203.
I lubed the shafts with some ATF on the th350 and speedo gear. I put no permatex on the 203. I was told as long as I have the paper gasket it should be fine.

I put no permatex on the 203 shafts or front as in the picture. How it looks in the above picture is how it’s mated to the th350 and the adapter. It is mated up on that tear drop.

I’m doing my best here, gentlemen . This is my first time mating this beastly 203 to th350. If I made a mistake by not putting permatex on there, so be it.

 

[TJ1978]

i have been saying this all along . the INPUT gear seal can be bad and let fluid in to the case . 1st post of mine in this thread and first sentence said input seal on 203 keeps them apart .

This is why I post pictures so I know what everyone is talking about. I apologize if I missed that sentence. I appreciate the help. But I’m also new at this so sometimes terms may go a bit over my head.

 

[sweetk30]

i know . and understand .

this is good your learning and best with pics like you posted . now you have a game plan .

and paper gaskets for me get at least some of this on both sides it helps . https://www.permatex.com/products/gasketing/gasket-sealants/permatex-high-tack-gasket-sealant/