The Stovebolt Site Forums The Shop Area Driveline *Servicing A 350 Turbo*

I have a 2001 5.3 Vortec engine with a 350 turbo (year unknown) in my 49 pickup. The transmission is leaking I believe from the pan gasket and the shifter shaft seal. I am not having any issues with the transmission and it shifts fine. I just got this truck about 4 months ago so I want to take it in and have the transmission serviced. I did this on a car some years ago and they flushed the transmission out and it never did shift right after that. I had to have it rebuilt. I fear the same thing may happen again. I was thinking of just having the fluid, filter, & gaskets changed along with the shifter shaft seal. What are your thoughts?

What's the condition of the fluid on the dipstick? Unless it's dark, gritty, or has a burned odor, leave well enough alone. Since it's impossible to get all the old fluid out because there's no way to drain the torque converter, stirring up things by dropping the pan and doing a filter swap doesn't accomplish much. The only thing "flushing" does is flush some of your money down the drain, and it could cause other problems.
Jerry

I agree..... I really hate to disturb anything but I need to get these leaks stopped. I've been using DEX/MERC Transmission Fluid and it's reddish in color. Not gritty, or any odor. The PO said that's what they did was just drain a replace the fluid and filter but you know how that goes. I believe nothing I hear and only half of what I see.

I build transmissions for a living and deal with the leaks all the time.
The shifter shaft seal is a common place for leaks to occur.
It is relatively easy to fix.
Disconnect the linkage from the shaft, purchase a new seal and the seal remover/ installer tool at your local auto parts store.
The tool has a tapered pipe that threads into the old seal. You then use the bolt in the kit to pull the seal/ tool out of the case.
Then use the other part of the tool to tap the new seal in place.

As for the pan gasket leak, its probably a warped pan rail due to over tightening.
You can remove the pan and straighten the rails and reinstall with a new gasket.
If your pan doesn't have a drain plug, you can add one while its off.
There are kits available to do this as well.

Do only what is necessary to repair the leaks. Many hundreds of thousands of fluid/filter changes have been done to every make and model of automatic transmission without any ill effects. As Jerry said you cannot get all the fluid out so some dirty fluid will remain no matter what you do. Nice red non smelly fluid is a plus as a starting point.🛠

Yeah I'm thinking change fluid, filter, pan gasket, and seal and call it a day.

Back in the dark ages, torque converters and fluid couplings could be disassembled and cleaned. Some converters also had drain plugs. It's possible to get more fluid out of a transmission by disconnecting one of the cooler lines at the radiator and running the engine to pump most of the fluid out, then refilling with fresh fluid. That's what some franchise shops call a "flush". As long as you don't let the pump run dry long enough to damage it from lack of lubrication, that's one way to pump most of the old fluid out. Some transmissions need to be shifted to "drive" to get the cooler circuit working.
Jerry

I'm for dropping the pan & replace the seal. Even some new fluid will keep the seals soft & the trans. clean.

George

Yup. That looks like the game plan.

Have them put a good magnet in the pan & fill w/ Dexron VI would be my advise.

I've been running Castrol Transmax DEX/MERC

Well I talked to some of the local boys about what transmission shop treats us AD owners the right way. Made the call today to get a price on fluid change (NO FLUSH OUT), shifter shaft seal replacement, filter, and gaskets. $150 to $200. Thought that was pretty reasonable. I just hate leaving the truck over night.

Leaking pans gaskets are a constant problem with older trannys that someone has messed with. Over tightening the pan bolts will bite one every time. Check to see if the pan bolt holes are convex on the gasket side. If so, hammer and dolly them flat with the pan gasket surface. As stated, a threaded bung hole is a good idea.
Does anyone have a fix for the speedo bullet o ring. I’ve replaced the o ring and remade/modified the cheesy bracket that holds the bullet in. Still get a drip now and again.

Try this stuff. It's not like RTV silicone and the other "rubber" sealers- - - -it actually cures to form a gasket. Coat the area of the "bullet" outboard of the O ring after giving the trans case and the insert a good cleaning with solvent. I've used it on places like 18-wheeler drive axle flanges and other hard to seal areas with very good results.

https://www.permatex.com/products/g...ealants/permatex-anaerobic-gasket-maker/

Jerry

There is a tiny seal where the gear goes into the bullet. It seems the replacement seals are not very good. The best way to service one is to buy a new whole new bullet assem. They are about $7 & are readily available. Make sure the shaft of the gear is not rough.
George