Gearbox oil change simplified

[Sailbad_The_Sinner]

After reading all the horror stories here about accessing, removing and replacing the speedometer gear drive, I got to thinking that there's got to be a better way, or at least an easier way. With most inboard/outboard boats, and outboard motors, you refill the transmission (outdrive) by pumping fresh oil in the same hole you drain it from. So my initial plan was to obtain an extra drain plug, drill and tap it for a Zerk fitting (or small valve), and then I discovered this little jewel -

https://www.amazon.com/dp/B0BTTSVTYX?re ... share&th=1

It has an integral check valve that opens when you screw in the fitting with the supplied hose attached, and closes when you remove it. intended as an easy way to drain crankcase oil into a disposal container, I figured the drain hose could be attached to a cheap little gear oil hand pump, like this -

https://www.amazon.com/dp/B0DWX7J2RH?re ... b_ap_share

Luckily , the black plastic nozzle on the pump hose fit so tightly in the fill hose that it didn't leak a drop. After pumping in two litres of gear oil, you unscrew the fill hose fitting, replace it with the supplied cap (which has a nice, snug, o-ring inside) and you're done!

The check-valve comes with an aluminum crush washer, rather than an o-ring, but with a stainless steel fitting going into an aluminum casting I didn't want to over-wrench it and so I applied a bead of non-hardening form-a-gasket instead.

A word of caution: since both sides of the check-valve (the side that screws into the gearbox and the side that accepts the final cap) are threaded the same, you stand a 50/50 chance of putting it in backwards the first time, or in my case a 90% chance...

[Tuga2112]

i think your overcomplicating the task.

theres a fill hole, its just a odd shape that is hard to undo. but welding a nut to it works fine, or you can fabricate an adapter for it.

considering the frequency the geabox oil gets changed (all my cars had it done once in their lifetime.. by myself after 30+ years.. im not planning on doing it again

[dapinky]

Whilst I don't see a problem with this, it does look a bit like a solution to a problem that doesn't exist..... but that is purely in my head!

I can see that there is a need for some way to get oil into the gearbox, and if this method works, it is just as valid as anything else.....

.... There is an argument for spending $40 dollars on a valve like this for future ease, and that same 'future ease' is why many people, having removed the 'D' shaped plug, then fit a "normal" sump plug spending $15..... except this method means that you don't have to spend half a day scratching your head to work out how to get the bloody original thing out, making up a socket, or welding a nut in a tight space - and, to me, that is worth the extra twenty bucks.

For those who never intend to take off the plug again (and I am in that group ), we need to recognise that although it won't be likely that the car will need another oil change during my lifetime, there is always the chance that the gearbox itself may need to come out for a clutch change, another repair, or a driveshaft needs to come off - and then that 'ease of use' scenario plays out and you can be laughing all the way to the kettle for the extra cup of tea that you will have time for

Although this modification isn't for me, I can see it's benefit for others, and thank the OP for doing the work to get it out there - in many ways it is these odd little titbits of information that make working on the cars a bit more fun - and I have spent many hours (days? weeks?) creating solutions for problems which probably don't exist anywhere else but in my head, only to find that no-one else would consider using the knowledge...... but I still do it to other cars, 'just because I can'.

That said, I do take issue with the part where it mentions adding 2 Litres of new oil, as 1.81L is the correct quantity for a gearbox that has been drained for a refill (2L may be right for one that has been disassembled on the bench and is completely dry inside, but not for a straight change). I am concerned that the levels will be too high, causing extra pressure on the seals and could contribute to a leak in the future (maybe tomorrow, maybe in 5 years time - I don't know.... but it will be annoying to have to remove the gearbox to change a seal, especially if it's the front seal and oil gets onto the clutch plate.)

[Geordie]

Hi guys
I removed odd shaped plug and drain plug,replaced with 2 subaru drain plugs (blue) they were obviously same thread and easy to locate and remove should you want to repeat gearbox oil change (simples)
Ps quick tap with punch and hammer loosened odd shaped plug then removed with adjustable grips
Geordie

[TorqueHorse]

After reading all the horror stories here about accessing, removing and replacing the speedometer gear drive, I got to thinking that there's got to be a better way, or at least an easier way...

Thanks for doing the work to identify this new alternative and sharing it!

[Simon_P]

That looks really neat.

Tuga - He's screwed it in, filled it up and driven off before you've got the welder out.

[Tuga2112]

Tuga - He's screwed it in, filled it up and driven off before you've got the welder out.

my welder is always out