Gearbox oil

[Jay Jay]

I have just cleaned out a 1968 Johnson 18hp gearbox and there was obviously water getting in somewhere, so when I find and fix the problem what oil should I use please

 

[dankilb]

I'd be very surprised if the usual options - e.g. Yamalube 'GL4' SAE90 Outboard Gear Oil - will do any harm.

You certainly don't get the impression that outboard gearbox design has changed much since the 1960s!

Btw - simple pressure test can often identify leaks

 

[Jay Jay]

I'd be very surprised if the usual options - e.g. Yamalube 'GL4' SAE90 Outboard Gear Oil - will do any harm.

You certainly don't get the impression that outboard gearbox design has changed much since the 1960s!

Btw - simple pressure test can often identify leaks

Thanks very much for the info, as for the leak there's a small hole on the front of the casing that I will have welded that should do the trick, Cheers

 

[dankilb]

Thanks very much for the info, as for the leak there's a small hole on the front of the casing that I will have welded that should do the trick, Cheers

Ah, I got you. Often it's dodgy drive shaft seals or sources of water ingress that are harder-to-find!

 

[MystyBlue2]

Best off getting the gearcase pressure tested to find the culprit unless there is a clear indication of a definitive failure.

They can leak from the 4 seals...

Top oil seal underneath the waterpump.

Bottom seal behind the prop

And the 2 oil drain/ fill screws.

If no obvious signs of which one has failed, Trying to determine which one is faulty can be a nightmare but a pressure test will find it.

 

[VicS]

I have just cleaned out a 1968 Johnson 18hp gearbox and there was obviously water getting in somewhere, so when I find and fix the problem what oil should I use please

Any outboard engine gear oil
Quicksilver is a readily available brand.
For an 18 hp engine the "premium " grade will be fine. No need for the high performance grade.

Don't pay over the top for oil with a outboard engine makers label.

 

[Jay Jay]

Best off getting the gearcase pressure tested to find the culprit unless there is a clear indication of a definitive failure.

They can leak from the 4 seals...

Top oil seal underneath the waterpump.

Bottom seal behind the prop

And the 2 oil drain/ fill screws.

If no obvious signs of which one has failed, Trying to determine which one is faulty can be a nightmare but a pressure test will find it.

Thanks, When I took the oil drain/fill screws out the drain screw was missing a seal so I have attended to that one but I will check the others even though I know about the small hole

 

[MystyBlue2]

Thanks, When I took the oil drain/fill screws out the drain screw was missing a seal so I have attended to that one but I will check the others even though I know about the small hole

Yup sounds like the culprit then.

Try going onto crowleyMarine.com and type in your engine serial Number. Scour the parts diagrams for the seal in question and copy and paste the part number into ebay OR go to a local Chandlery for the part and for the correct oil to refill.

While your at it, It might me worth taking off the prop and inspecting the lower seal behind the prop.

Thin fishing line has a tendency of finding its way behind the prop and shredding that seal to bits without you realising causing leaks too.

 

[Jay Jay]

Any outboard engine gear oil
Quicksilver is a readily available brand.
For an 18 hp engine the "premium " grade will be fine. No need for the high performance grade.

Don't pay over the top for oil with a outboard engine makers label.

Thanks again

Yup sounds like the culprit then.

Try going onto crowleyMarine.com and type in your engine serial Number. Scour the parts diagrams for the seal in question and copy and paste the part number into ebay OR go to a local Chandlery for the part and for the correct oil to refill.

While your at it, It might me worth taking off the prop and inspecting the lower seal behind the prop.

Thin fishing line has a tendency of finding its way behind the prop and shredding that seal to bits without you realising causing leaks too.

That's the great thing about this site everyone is so helpfull, Thanks a lot to everyone Cheers