tgilligan

Hi,
I used some fluorescent leak detection dye and added to the ATF and took for a drive. Got the trans up to temp and pulled back into the driveway to check for any leaks. As I suspected, I didn't see any active leaks coming from the obvious spots, in fact after cleaning the trans prior to the drive, it looked clean and dry. For reference, I've already changed out the kickdown, tail shaft seal, shift shaft selector seal with new. I then checked all those spots first to rule anything out. Then I checked the speedo housing/cable, dipstick tube, pan, trans cooler lines, modulator and the other open areas......dry. I had long suspected that it primarily leaks after shutdown and longer periods of it sitting (few days) so I'll go back and check with my UV light again at night after it cools to see if anything new shows up. The only single spot I saw was the bottom bolt of the plastic torque cover had a small dot of dye showing, leading me to believe it might be either the torque converter or the pump seal area.

Any other thoughts/ideas? I was hoping it would be something obvious or at least clear to get to but it's looking more and more like the trans is going to have to get pulled and possibly rebuilt with new seals.

matt69olds

Keep driving/checking until you can determine where it’s coming from. Pull the inspection cover, if the pump seal is leaking the dye will be on the pump and converter. No point in pulling it until you know exactly what to fix

tgilligan

I went out tonight and there was a very small amount that looks like it flung from the slip yoke. I didn’t see any on the driveshaft or spider bearing, it was only on the bottom of the floor pan. I had the tail shaft seal and bushing replaced already so maybe my yoke has the weep hole in it? Thought it was weird it was only on the floor pan in a flung pattern and not anywhere else. I expected to see some on the drive shaft, yoke or bearing. I’ll keep trying and I’ll check the inspection cover tomorrow as well.

tgilligan

Update 6/22
used the dye and found a leak at the speedo housing, dipstick tube and kickdown cable. Speedo was a needed fix anyways as I updated to a 37 tooth gear so I crossed that off the list.

I picked up a new dipstick tube but it wasn’t the right length and the bolt clamp wasn’t in the right spot so I pulled the original and replaced the o-ring at the bottom. Did the same with the kickdown as the shop that did some work for me installed that cable while it was being worked on but they didn’t put an o-ring on the cable, they just used RTV. It’s not the top hat style seal it’s just the o-ring. Put one that I hoped would work.

Turns out the o-rings either are not the correct size or some other issue as it’s still leaking from those two spots. For both the dipstick and the detent cable, am I supposed to use RTV as well as the o-rings? I hoped the o-rings would be enough but perhaps they are not the proper size/thickness. I tried to size it as close to the original as I could. Thinking of switching the dipstick to an aftermarket with a different type of case seal to see if that’ll work. Any suggestions?

matt69olds

The sleeve type seal is much more forgiving. I’m sure summit or JEGS sells a aftermarket dipstick and tube that uses the later seal. I know for a fact Coan sells them. Whoever you buy it from, make sure you tell them is NOT A CHEVY 350. Make sure you tell them is. BOP 350, NOT A CHEVY 350. Make sure it’s absolutely clear, ITS NOT A CHEVY 350 trans!! They will not interchange. Seems like the summit and JEGS guys can’t comprehend that there are other 350 engines and transmissions other than a Chevy.