Trans leak - 79 k10

[tommartin]

I have a 79 k10 with a TH350 trans and NP 203 t-case.

I pulled in the drive way the other day and noticed a lot of trans fluid leaking from where the trans and t-case meet.

here is a picture of where it is leaking.

What are your guys thoughts?

[66skylarkpost]

thata 350 turbo , they all use a large square o-ring there. app. 6" in diameter. ive never seen one leak unless it comes loose . either way u need to drop the transfer case to get to the bolts, then drop the adapter and change it

[tommartin]

Thanks for the info, I'll check it out today. Does the whole trans have to come down to get to the t-case? Is there a name for this o-ring, I was getting a lot of different results when looking for it.

Thanks for the info.

Tom

[ray_mcavoy]

Originally Posted by tommartin

Does the whole trans have to come down to get to the t-case?

No, you should be able to remove the t-case separately. You'll need to put something under the transmission to support it before you remove the adapter plate though.

Originally Posted by tommartin

Is there a name for this o-ring, I was getting a lot of different results when looking for it.

It's a square-cut type O-ring. I'ts the same as what's used between the trans case and tail housing on a 2-wheel drive. So I think most places call it a case to tail housing O-ring.

[stampy]

Keep us posted Tom! I have a 79 K10 that seems to be leaking in the same spot.... and left a nice present for me on the dtiveway.

[tommartin]

Start on getting ready to pull the transfer case out, I have been searching and reading on the best way to do it… one thing that is clear is that it is heavy and don’t get smashed.

One thing that I was wondering about was the bolts from the tail of the trans to the transfer case….

You cannot see them from the bottom because they are on the other side of the adaptor and the transfer case is covering that side.



So it looks like I have to take out the 7 bolts that go into the transfer case, and it will come down, and the trans will stay in place with the 4 bolts that go through the adaptor into the trans….

I started loosening everything up, front and rear drive shafts, I did take off the floor hump, it made the top bolts easy to get to. I don’t have any carpet or anything on my floor so the hump was easy to take off.

I'll get some pictures of what’s going on just in case anyone is interested.

[tommartin]

Ok guys, so I have been working on this kind of slow like, just whenever I can.

Yesterday I had all the bolts out, i left the rear drive shaft connected hoping it can kind of keep the t-case from just falling out.

So I had two floor jacks under it and all the bolts out, from the top inside the cab, I started to pry the t-case from the adaptor, they got about an inch apart, maybe less.

About how far back is the t-case going to have to come before it will drop down?

I put the 3 top bolts back in for now…

[swamp rat]

I could be wrong but i think you need to pull the T case all the way out, even if you separate the adapter from the tranny i don't think you will be able to pull it back far enough.

[tommartin]

Ok, so I finally got it out....

I had to edit my post, I was lost for a minute, but then read back through the advice given to me already and I’m back on track.

Got the t-case out:



So I only had a floor jack, so I made a cradle type thing out of some 2x4.



It did its job for sure…



And with a little pulling and some help from good ol' dad... it came right out.

[swamp rat]

Nice idea! How was the balance?

[tommartin]

I bolted it to the Jack, it still needed some guidance on the way down...

[tommartin]

I pulled out the adaptor and the seal yesterday…

Here is a pic of the location of the o-ring:



Here is the o-ring:



because it is a square o-ring, I was wondering what the heck it looked like. It looks like a rubber band… and the square part is the cut of the rubber not the shape of the band… reading back through the post it says “square cut o-ring”

Trans side of the adaptor:



t-case side of the adaptor:



Now, I just have to get the new seal/o-ring and put it all back together...

Im going to need to replace my trans mounts also.

Anything else I should consider changing or taking a look at before I put it back together?

[swamp rat]

While its out i'd consider any shaft seal on input or output shafts. Did you have any problem with the transfer case filling up with tranny fluid? that would indicate the transnission is pumping tranny fluid into the case.

[tommartin]

No issues with the t-case filling with trans fluid. The seal looked like it was in good shape.

It took a little looking but I found my case to adapter gasket at a local shop.

[RPBurris]

Originally Posted by tommartin

No issues with the t-case filling with trans fluid. The seal looked like it was in good shape.

It took a little looking but I found my case to adapter gasket at a local shop.

Got a part number for that gasket and O ring by any chance??

[tommartin]

So, finally finished up and put the t-case back in.

It is a real pain with just a floor jack, and it did take two people.

Next time, I think im going to spend the $80 and get a trans jack from Harborfright.

Thanks again guys for your help.

Back on the road:

[swamp rat]

I agree on the jack, job well done!

[waco]

I used an ATV style jack that had 2 rubber cover legs & that same home made jig to get mine in & out. It was very stable & only took 1 person to remove & install. As for the gasket, if you can remove the old one in somewhat of 1 piece, you can do as i did & make 1 from .030" thick stock gasket material for a couple bucks that you can get at most auto supply stores (took about 20 minutes).