older outboard 'major' service

[ashh]

Hey guys, I just bought a Jap version 4hp Mercury 2 stroke for my 3m flat bottom punt.
Its a 2008 model and was used exclusively as an auxiallary motor on a 5m ski boat so hasn't had a hard life, and the owner 'said' they ran and flushed the little motor after the boat was used even if the little motor wasn't used, so seems it has been maintained fairly well with little actual usage.

Did all the usual pre purchase motor test and looked the goods, it also started easy from cold, strong tell tale, idled smoothly and selected gears nicely, so I bought it.
I'll be using it in the canals as a "get to" fishing spot motor then be using the electric motor where I will be fishing...

I'd like it to be as reliable as possible so want to do a complete and thorough major service on it, impeller, gear box oil, filters etc etc

What other parts should I re-new? like any seals, gaskets, rubber fuel lines etc?

There is a small amount of surface corrosion around the cylinder head gasket, how should I best treat this so it doesn't get any worse?
Appreciate any advice or input, cheers !

[ashh]

can just about hear the crickets in here...

anyone know of any decent Facebook groups I can ask questions like this on, as it seems that's where all the cool kids are hanging out now....

[Noelm]

It's a pretty simple motor, do you know when the water pump was last replaced? Rather than just do "stuff" I would give it a few good runs first and see if anything actually needs doing, a gear oil change and maybe new plugs would be a good start after a bit of running.

[ashh]

the previous owner, wasn't very mechanically minded and she said she had never replaced the impeller due to the low actual usage of the motor.
For piece of mind, I'll replace the plug, impeller, fuel filter, gearbox oil and possibly the head gasket. There's some corrosion around the head gasket joint which I've been told is common but I want to prevent it going any further... Would that be a case of just removing the head, cleaning the corrosion off and replacing the gasket while I'm at it?
Or is that going unnessasarly overboard and assuming that the corrosion more than likely just be surface based and just treat what can be seen with a rust killing product? Thanks for the reply noelm :)

[Noelm]

Corrosion around the gasket is common, I don't think it is a major concern, that said, as long as you don't break any bolts, removing the head is a simple job on those if you want to replace the gasket, if the water pump has never been done, then maybe it might be time to do so, buy a complete kit, rather than just the impeller.

[ericcs]

can't confirm for every merc model, but before you go pulling heads off, confirm first if it has a head to pull off. Mercury pistons used to be installed through the crankcase. if yours is like this, then all you have is a water jacket instead of a head.

[ashh]

yeah, before I go pulling anything apart I'll look up a parts diagram for my motor.

On another note, I've seen that afew motors say for example the 2hp through to the 6hp are all basically the same motor, most noticeably having the same cubic capacity, can you squeeze afew more ponies out of a 4hp to get it up to a 6hp rating with some simple mods or is it a bit more involved than that?

[scottar]

I wouldn't be too concerned about the gasket corrosion Ash. Every motor I've ever owned seems to do it. If you want to check the condition of the water jacket though then you may as well replace it while you have it off. I usually spray the edges with lanolin. The list you already have is pretty much all I would be doing with the addition of grease everything that should be greased and check / grease the prop shaft - these little engines really aren't much more than a lawn mower with a water pump.

[ashh]

thanks fellas, will see how it performs on the little punt in the morning :)

[rayken1938]

One of the main issues with a motor that has not been serviced regularly is corrosion around the bolts if any of the bolts are frozen you may have problems. Using a bit of heat and a rattle gun set on low torque can assist in removing stubborn studs.
Cheers
Ray