Transmission Pan Gasket Filter

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14 Sep 2010 21:13 #980 by Kiln_Red
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!! :eek:

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?

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15 Sep 2010 20:19 #1014 by 87 Shark
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.

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15 Sep 2010 20:49 #1017 by Kiln_Red
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.

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16 Sep 2010 08:38 #1020 by SeanR
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.

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16 Sep 2010 09:15 #1022 by Kiln_Red

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.

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16 Sep 2010 10:21 #1028 by 928mac

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!! :eek:

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.

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16 Sep 2010 13:15 #1030 by Calgary Ole
If you have not changed the tranny fluid/filter before, there is a couple tips I learned when I did mine.
#1 Lift car level and high
#2 Clean the road dirt and filth from the tranny and surrounding area to avoid any dirt getting in when reinstalling the pan. There is usally plent of loose dirt up around the resorvoir where you will be refilling the fluid.
#3 Cover yourself and the floor with as much protection as possible as tranny fluid gets everywhere.
#4 Drain from plug on tranny and turn engine by hand until you see plug in tourque converter, remove and drain t-converter. You will need a drain pan big enough to hold about 9 litres IIRC.
#5 Remove bolts on the pan and drop down...there will be more fluid raining down on you and your floor. Its messy.
#6 Make sure ther is no dirt around the gasket surface and re-install with new filter. Do not overtighten the bolts. I think mine were spec about 6-8 ft/p. Look up Andrew Olsons sig as he has the specs for most model years.
#7 Tighten drain plugs to spec and fill...mine was about 9 litres.
Filling is the hard part and many have clever ways of doing this. I used a simple .5 litre suction pump and took my time to not get any dirt in the resorvoir.
#8 Run car with tarnny in drive up to temp and then check level with mirror and flashlight. If you got the resorvoir good and clean it is esay to see the level marks. Again this is tricky with hot exhaust but can be done before removing from the jackstand with emegency brake on. Probably not recomended unless you are comfortable with your stands.

I am sure there is something I missed so feel free to add.
If you have a lift the job is much easier!
Ole

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16 Sep 2010 15:46 #1033 by 87 Shark
Austin, I had the tranny flush done at a Pennsoil oil change centre. I have asked about the 928 and they said they can acomodate me. I would check with your local trans mission service centre or the like.The fluid pump shows the old oil removed and new oil(fluid) replacing it.It was very slick and no mess. The car stays on it's wheels over top of a pit. Once emptied the magnets and filters can be replaced.The fluid is drawn out via the cooler lines, not from the pan drain. Hope this helps, good luck.

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16 Sep 2010 23:03 #1050 by xstepson

#3 Cover yourself and the floor with as much protection as possible as tranny fluid gets everywhere.

Filling is the hard part and many have clever ways of doing this. I used a simple .5 litre suction pump and took my time to not get any dirt in the resorvoir.

Ole


I have determined that without a lift, it is virtually impossible to change transmission fluid without it running down your arm and getting all over you.

I do not know what the first year was (but I suspect it was 1987 and the advent of the S4), but for sure the S4's and above have a hex fitting covering a one-way valve directly into the transmission. Unscrew the hex fitting and attach a fuel line-size hose and a pump and pump the fluid into the transmission without having to remove the reservoir cap.

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16 Sep 2010 23:40 #1051 by SeanR
John and I differ on this approach. He does it the factory way. I do it my way. :p

Pull the cap off (this is after you've changed the filter, put the plugs back in with new rings) get a walmart hand pump that fits the 1 gallon ATF jugs and just pump the stuff in. Get about a gallon in, have some one start the car quick to get the pump moving. Shut it off, pump more...repeat a few times then when the level is not moving much, keep the car going and have someone moving the selector all over the place, as you pump in more.

Yea, you might have a small bit of fluid on your arms, hands, ground, but hell, if your car can't bleed on ya, what can.

I have determined that without a lift, it is virtually impossible to change transmission fluid without it running down your arm and getting all over you.

I do not know what the first year was (but I suspect it was 1987 and the advent of the S4), but for sure the S4's and above have a hex fitting covering a one-way valve directly into the transmission. Unscrew the hex fitting and attach a fuel line-size hose and a pump and pump the fluid into the transmission without having to remove the reservoir cap.

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