Transmission Pan Gasket Filter

I was thinking of servicing my transmission on my '84 before it assumes daily driving duties again, but then I came to a realization about something... The transmission probably hasn't been serviced since at least '96!!

That said, I'm a little hesitant about doing it now. I have seen instances, first hand, where servicing older transmissions with no history of regular maintenance has ruined them within the first 200 miles of completing a gasket & filter job. Basically, what happens is the new fluid flushes out the cruddy remnants left behind by the old fluid thus stopping up the new filter and burning up the transmission. Brad, I am sure you've seen at least a few of these such instances happen in your career as a mechanic.

What do you guys think?

When I had my truck tranny serviced I switched to synthetic fluids. The shop hooked the truck up to a mechanica lpump and performed a power flush to extract the old fluid. The machine then pumped in the new fluid. It is supposed to get all the fluid out of the torque converter as well. It's kind of like power bleeding out old brake fluid. Flush it and run it then check filters for debris.

Who performed the flush & refill for you? How much did it cost to have it done that way? Sounds quite a bit safer for an older transmission like mine.

The Merc trans isn't like a Chevy one. On my truck, I passed the 150k mark and was advised to not change it, just replace the trans when it finally quits. Don't worry about changing the fluid/filter on the 928, it's best to do it.

SeanR;1055 wrote: The Merc trans isn't like a Chevy one. On my truck, I passed the 150k mark and was advised to not change it, just replace the trans when it finally quits. Don't worry about changing the fluid/filter on the 928, it's best to do it.

Sean, I am happy to have your input on this. I'm sure you've probably performed the fluid/filter service on dozens of 928s. I'm assuming you haven't experienced any issues as I have with other vehicles. That said, I feel much more comfortable doing it now and I will probably just do it myself. Thank you for your response.

KilnRed;1015 wrote: I was thinking of servicing my transmission on my '84 before it assumes daily driving duties again, but then I came to a realization about something... The transmission probably hasn't been serviced since at least '96!!

That said, I'm a little hesitant about doing it now. I have seen instances, first hand, where servicing older transmissions with no history of regular maintenance has ruined them within the first 200 miles of completing a gasket & filter job. Basically, what happens is the new fluid flushes out the cruddy remnants left behind by the old fluid thus stopping up the new filter and burning up the transmission. Brad, I am sure you've seen at least a few of these such instances happen in your career as a mechanic.

What do you guys think?

I rebuilt transmissions for GM and Ford for a few years.
I would change my fluid without hesitation.
Think of it like you would your engine.
If it slips due to the service, it would have left you sitting in a week anyway.
A trans flush is a good Idea, remember that it is a hydraulic pump and needs clean fluid that may even help soften up some stiff seals and give a nicer shift.
Don't blame a service for failure.
I've tried to save them with a service but it never works if they are on there way out.
On the road if it starts to slip, replacing 1L with 1L of Mercon will help get you home as it is less slippery.