Gear Lube change in Merc 20hp 4s

[Tonus]

Had a quick question about changing the gear lube in my engine; a Mercury 20hp 4 stroke EFI.
I left the top and bottom screws open for about 10 minutes to drain out… the old oil seemed fine for colour.
I then squeezed 2x tubes of SAE 80W-90 into the bottom Fill hole. Everything I’ve seen and read said that the oil should spill out of the vent hole above when full, but after really squeezing the last drops out of these tubes nothing came out of the top.
Seems like a stupid question but can I just buy another tube and keep going? I thought the service kit that I bought would give me enough lube to fill it and a little bit more to make sure it was full. It’ll be a shame to waste nearly a whole tube… Is there any harm in opening it back up tomorrow or the day after?

I’ve put the screws and new seals in half-tight for now.
The other question I had was about the seals… They are a blue rubber one side had a kind of grey circular band in the middle. I assumed this would face into the engine not into the screw-does that sound right? Many thanks

[spartacus]

Get yourself a Quicksilver pump dispenser. I used to use the 237ml tubes, but it's a messy affair. Chances are it just needs a little more gear oil, but yes it should run out of the top-hole so level is spot on, then close of drain-fill screw, then finally the vent screw. A decent flat-head screw-driver with a pair of claw-grips can provide the final torque.

Opening it up is fine, do that before it goes anywhere near water would be my advice.

Tohatsu use standard fibre washers that compress, but chances are you are using Mercury Mariner drain seal washers. The side with the grey insert which looks slightly raised will provide the waterproofing and should face the engine, that would be my guess.
https://www.bottomlinemarine.com/pro...880_3532.shtml

[Tonus]

Thanks Spartacus - that's great. Yes I thought about a pump - the manual has a picture of the tubes and they came with my maintenance kit so I just went with them.

I'll definitely get a pump next time... a litre bottle is so much better value too!


Thanks for the steer on the washers - those are exactly ones I have. Cheers

[Matt]

The pump setups are decent, but ff you're particularly enthusiastic, you can use something like this with the nozzle removed and the hose & gearbox adaptor on it instead. Makes refilling a doddle.

https://www.toolstation.com/pressure-spraygun/p41642

[beamishken]

Seems like a stupid question but can I just buy another tube and keep going? I thought the service kit that I bought would give me enough lube to fill it and a little bit more to make sure it was full. It’ll be a shame to waste nearly a whole tube…


Yes no problem! no need to over complicate things with special pumps etc at this stage, another squeezy bottle will work fine. Stick a lid on it & use the rest next year. It doesnt go off

Sent from my SM-G950F using RIB Net mobile app

[Tonus]

Originally Posted by Matt

The pump setups are decent, but ff you're particularly enthusiastic, you can use something like this with the nozzle removed and the hose & gearbox adaptor on it instead. Makes refilling a doddle.

https://www.toolstation.com/pressure-spraygun/p41642

That looks good Matt - next year I'll look into it as swapping one tube of oil for another like Indiana Jones is a messy business!!

[Tonus]

Originally Posted by beamishken

Seems like a stupid question but can I just buy another tube and keep going? I thought the service kit that I bought would give me enough lube to fill it and a little bit more to make sure it was full. It’ll be a shame to waste nearly a whole tube…


Yes no problem! no need to over complicate things with special pumps etc at this stage, another squeezy bottle will work fine. Stick a lid on it & use the rest next year. It doesnt go off

Sent from my SM-G950F using RIB Net mobile app

Good to know it doesn't go off after a year - thanks.

I bought a new tube and it filled to the top in one squeeze definitely spilled more than I pumped!

[Matt]

Originally Posted by beamishken

Seems like a stupid question but can I just buy another tube and keep going? I thought the service kit that I bought would give me enough lube to fill it and a little bit more to make sure it was full. It’ll be a shame to waste nearly a whole tube…


Yes no problem! no need to over complicate things with special pumps etc at this stage, another squeezy bottle will work fine. Stick a lid on it & use the rest next year. It doesnt go off

Sent from my SM-G950F using RIB Net mobile app

Ken's right (I assume your name is actually ken?) - it's not necessary to have a pump or anything....but I've also covered myself and the driveway in enough gear oil over the years to appreciate a bit of convenience when it comes to filling.

[Tonus]

Originally Posted by Matt

Ken's right (I assume your name is actually ken?) - it's not necessary to have a pump or anything....but I've also covered myself and the driveway in enough gear oil over the years to appreciate a bit of convenience when it comes to filling.

Matt - yeh I can still smell the oil I spilled on my lawn every time I walk past! Think I’d rather have a pump next year!
The litre bottle of gear oil is WAY better value for money too - especially if it keeps well till the following year.
I live and learn with this stuff. I’ve all but finished the first service on my outboard which if the first I’ve owned and it’s been a really satisfying experience. Lots of help from the good people on this forum - had spurred me on. Newbie will one day be an old hand haha

[Matt]

Nice one! Keep it up.

It's very satisfying doing it yourself, saving a few quid, and also means that if you ever do have an issue out at sea, or even on the slipway, you know more about the boat so have a decent chance of fixing it and not ruining a nice day out.

I have a bravo drive on my boat - takes about 3 litres for a fill, so I buy quicksilver 10 litre cans and their pump. Takes a few years to use a full can, but is the most economic way of getting the oil I find.

Not such a big deal on the smaller gearboxes, but certainly on the bigger hp units, don't compromise on the oil, always used exactly the right stuff as specced - the loads on the gear teeth is MENTAL.