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Mazda M5OD-R1 transmission drain/fill plug gaskets


rosscob

Well-Known Member
Joined
Sep 3, 2023
Messages
75
City
Oregon Coast
Vehicle Year
1988
Transmission
Manual
I need to change the fluid in my '88 Ranger with the M5OD-R1 transmission, can I use a plastic gasket on the drain/fill plugs or should I buy the copper or aluminum gaskets? I've got a couple of the plastic ones from another job that will fit but the parts stores around here only sell assortment packs so I'll have to buy 2 to do the job. Sorry if this seems like a stupid question.
 
Factory is aluminum and it's all I've ever used. Copper might work. The transmission might get to hot for plastic. I honestly don't know how hot manual transmissions get compared to automatics. So, plastic might be ok but I just don't know.
 
Plastic depends on what kind really. However anything sold for an oil pan seal should be fine.
 
There is no pressure at the fill plug and only 4lbs at the drain plug(2.5 quarts of ATF)
So nothing on the Fill Plug, just tight
Drain plug should also be fine as is but plastic washer should be OK if surface or plug has scratches, i.e. rough surfaces, so poor seal

Transmissions are vented so no pressure builds up as oil warms up, so just the weight of the oil against the Drain plug, 7.2lbs/gallon
 
Last edited:
It's only like 5" of "head" so in reality it's like .2psi tops. Aluminum or plastic should be fine
 
Mind the TORQUE--only 36 ft. lbs... don't want that cheap steel plug stripping out your EXpensive ALUMINUM tranny case!

Closest replacement for aluminum crush gaskets is NAPA Part # 704-1974... I had to buy 10 though... figure 4 for the future and 4 free to a good home.

 
It's only like 5" of "head" so in reality it's like .2psi tops. Aluminum or plastic should be fine
Yep, ATF definitely leads a much easier (and lower temperature) life in a manual than in a mix-master A4LD
 
There is no pressure at the fill plug...
Well, when sitting still, level ground, engine off. ;) I had a Fill-plug leak... was it "driven" by the splasher thingy on the input shaft? Bouncing down trails? Nope, but when you have a BLACK truck in the SUN-belt, shaded/covered parking is king. For 3+ years had a sweet shady spot at work, but the right wheels were a good 12" higher than the left... made it hard to take a nap, but I could pretend I was on a track with highly banked turns! :ROFLMAO::cool:
 

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