Kylel

iTrader: (2)

I recently tore down a '98 4L80E and found a crack in the case where the valve body mounts. I'm not sure what this passage does, so I'm hoping somebody can tell me if it will be a problem for me. If so, can I fix it somehow?

Hopefully from the picture you can tell where the passage is. Basically, you can see the rooster comb and shift rod at the top of the picture. You can see the crack in the lower part of the picture on the same side as the linkage:





Here is a side shot showing the crack going all the way down:





I am doing a basic rebuild and adding Jake's D3 transbrake. Thanks for the help!

Ferocity02

iTrader: (60)

That is the line passage, perhaps it cracked due to excessive pressure? You may be able to weld it back but I would look very carefully to see just how far the crack goes.

Kylel

iTrader: (2)

Thanks, thats what I needed to know. That explains why the transmission lost all gears. I don't know if it would better to try to TIG weld up the crack or get another case. I can't get a drill bit into the end of the crack to prevent the crack from continuing further. I suppose JB weld probably won't cut it here...

mrvedit

It looks like there are several square inches of surface area. Multiply that by 200 psi and you have hundreds of pounds of force on that broken wall. I doubt JB weld would last long; probably break up and ruin the seals.

SnIpEz

iTrader: (4)

I would not recommend JB weld for something like this. I wouldn't bother trying to get it welded either, personally. I recommend just replacing the case altogether. Check with the nearest core supplier, search around on Google a bit. They may have some cases in that style of 4L80E around.

Ferocity02

iTrader: (60)

I would think it would be difficult to find just the case. He might have a to buy another trans.

I agree that JB weld won't cut it here.

Jake's Performance

iTrader: (2)

Yes,
make that 350 psi in reverse...

Kylel

iTrader: (2)

I found a local shop that will sell me a bare case for $150. I think for peace of mind I should just do that.

Circle-D

iTrader: (21)

Absolutely, $150 is a good price and eliminates the worry.

Chris

Kylel

iTrader: (2)

I bought the case, rebuilt the trans and fired it up for the first time a couple days ago. Got the fluid level looking good, but I had no gears in any direction. I pulled a cooler line and got just a trickle of fluid coming out while engine was running. I pulled the pan and found that the TCC valve had fallen out of the bore and into the pan. I'm guessing I didn't have the snap ring fully seated. I just wanted to double check- could this valve falling out be the cause of my zero line pressure?