Yamaha 3-5 hp outboard circa 1975?

[Todaymueller]

I have had in my garage for many years a 3-5 hp yamaha outboard 624-S 01641. I am guessing 624-S is the model the rest the serial number. A mate, who is a wizard motorcycle mechanic, has given it a good clear out and has got it up and running. Now he doesn't want to run it for long without changing the gear oil and giving it a good grease. Has anybody got any suggestions as to where I might download a manual or which oil and grease should be used?

 

[VicS]

Owners manuals are available to view on the Yamaha website also parts lists/exploded diagrams but not for engines that old.

http://www.yamaha-motor.com/outboard/service/servicehome/home.aspx

Parts list and diagrams also to be found on www.boats.net but only from 1980 onwards.

To check your engines age look up the meaning of the "year letter" which should be separate from the model and serial numbers. There is a key to the code on the Boats.net site.

Use whatever water proof grease you can find readily available ... buy Yamaha or other outboard brand name grease if you want to "splash the cash".

The gear case oil will be a high viscosity outboard gear oil ( around sae 80W-90) Yamaha obviously offer their own brand. Quicksilver is generally available at most chandlers.

If needs must use an automotive EP90 gear oil but be aware that it does not contain the corrosion inhibitors or the emulsifying agents that would help to protect against the effects of water ingress.

Always change the oil at the end of the season and if the old oil is milky or if there is any water visible then new seals will be required.

Use an two stroke outboard engine oil to TCW3 spec in the fuel ( 50:1 is a safe mix if in doubt)

Assuming it's water cooled ( there were a few air cooled Yammies) check the cooling water flow. If in any doubt change the pump impeller.

 

[Todaymueller]

Thanks for the infomation, I have to go to the chandlers this week for some bits 'n' bobs for my kayak. So I will see about it then.