Servicing a Merc 50hp

[JSP]

I want to service the Merc 50hp (clamshell?) that I got yesterday. Any advice for do's and don'ts plus where to buy bits from would be great.
I'm thinking of respraying the cover though as it's got a few scratches on it, the leg is mint. Can you still get hold of the stickers?

[JSP]

Any ideas?

[PeterR]

Get the spark plugs from you local Motor factors and gearbox oil

[JSP]

Yeah the spark plugs are no problem it was more things like the impeller which I've never done before.
Hasn't the gear box oil got to be marine grade?

[PeterR]

I feel thats just sales b-llsh-t.Ask yourself why.Is the oil in contact with water.and if it was what will happen you will need to replace imeadiately.

[JSP]

That sounds like a sound argument Peter
Seems for the impeller I need the exact year. Any ideas how to find out the date on these mottors? Been told it looks like a 88/89?

[PeterR]

The impellar is simply to get but again questonable as when to replace.I recently had a boat with an amazing condition 1983 90 hp mercury one owner from new .It pumped water well.The owner who was a machanic swore blind the impellar had never been replaced.I did in this case have it done.Its easey if your practicle.

[JSP]

As long as I've got half an idea I love getting my hands dirty.

[JSP]

pics

[Poly]

Originally Posted by JSP

Hasn't the gear box oil got to be marine grade?

Search here - there are differing opinions, but most people do use the marine stuff. You'll get that in any engine dealer/yacht chandlers.

As for the impellor I would definitely try to change it on an engine that is as old as that. It only costs about £15. There is a good thread here by Richard B on how to do it. Probably your worst case is you can't get the bolts out to get the leg off etc. If that is going to be a problem better to find out now.

[Andy JC]

Have a look here to find part's and part numbers.

Also useful to see how the engine goes together

[Pete7]

One advantage with marine oil is that it comes in a tube with a nozzle that you will need to squirt the oil from the lower hole until it flows out of the upper hole. This ensures their are no air pockets. How many do you need, not sure on a 50 hp but best to have 3 set up ready to go because you need to be quick or the oil will run out. A second pair of hands ready to pass them to you is useful. When you drop the gearbox to do the water pump their is probably a hidden bolt under the annode to watch out for. The rest is childs play so long as you don't upset the carb balance or timing.

Worth also giving the cable end that goes into the steering box a good squirt of grease whilst your doing the engine, its often neglected. Easist way is to take the cable out and then wind it back in again after a good greasing. You can try grease on the ram end but it won't stay their long.

Pete

[ruddles]

it will almost certainly be SAE 80 or 90 gear oil, there isnt a marine version afaik, so just use car stuff, its the same, if you look in your motor factors you will get the tube with the pipe and the neck of the tube normall fits stright into the bottom filler hole.
Fist thing to do is remove the leg if you want to check the impellor, that will give you a good indication (removing the leg) of the general care that has been taken of the engine re flushing and servicing.

[jyasaki]

Originally Posted by Pete7

One advantage with marine oil is that it comes in a tube with a nozzle that you will need to squirt the oil from the lower hole until it flows out of the upper hole. This ensures their are no air pockets. How many do you need, not sure on a 50 hp but best to have 3 set up ready to go because you need to be quick or the oil will run out.

In theory (not so much in practice, though) you remove both plugs, allow the leg to drain, then, as Pete says, squirt the oil up from the bottom hole. When it starts to flow out the top, you replace the *top* plug. The resulting vacuum will hold the oil in the leg long enough to get the lower plug in.

In practice, it makes a mess no matter how careful you are. I do find that the screw-in pump thingies (and a bottle of oil) tends to be neater than trying to use the tubes. Might be just me, though (I may be squeeze-tube challenged or something.)

jky

[bedajim]

Originally Posted by jyasaki

In theory (not so much in practice, though) you remove both plugs, allow the leg to drain, then, as Pete says, squirt the oil up from the bottom hole. When it starts to flow out the top, you replace the *top* plug. The resulting vacuum will hold the oil in the leg long enough to get the lower plug in.

In practice, it makes a mess no matter how careful you are. I do find that the screw-in pump thingies (and a bottle of oil) tends to be neater than trying to use the tubes. Might be just me, though (I may be squeeze-tube challenged or something.)

jky

I always pump a some oil into the top hole after draining to flush out any solids left behind from the old oil

Jim

[Chris]

When you do the oil change whip off the prop and run the engine on muffs at idle in gear for a few minutes to warm up the oil in the gearbag before draining.

[davej]

Hi

I have an 80s 3 cyl 60hp 2 stroke Merc and recently obtained all the parts for a full service from Key Parts in Watford, they are on the web. While a standard service is pretty easy I would strongly suggest that you get a workshop manuel.



Required parts:

Spark plugs

Gear oil, plus two new washers for the drain and vent screws

small plastic inline filter

impeller

Fuel pump diaphram kit

maybe a spin on fuelfilter/water seperator.


All this for mine came from Key Parts for £72 inc tax and shipping.

Speak to Richard.

Good Luck

Originally Posted by Polwart

Search here - there are differing opinions, but most people do use the marine stuff. You'll get that in any engine dealer/yacht chandlers.

As for the impellor I would definitely try to change it on an engine that is as old as that. It only costs about £15. There is a good thread here by Richard B on how to do it. Probably your worst case is you can't get the bolts out to get the leg off etc. If that is going to be a problem better to find out now.

[Locozodiac]

Originally Posted by bedajim

I always pump a some oil into the top hole after draining to flush out any solids left behind from the old oil

Jim

I'll second that internal gear cleaning method, you could use any good quality gear oil 80-90 grade or multigrade 80/90 works perfect.

Happy Boating

[9D280]

I'm looking at replacing the Yam with one of these. (see my other posts regarding helicoils )

Any of you guys & gals know of any common problems with them? I've seen a few refs to the top cyl running slightly hotter, but that can be cured with a higher heat tranfer spark plug.


Ayhow, if you're dropping the leg, there's an interesting article on Iboats on a cooling problem on a 60. Might be worth chasing it. (link is on the other PC, so if you can't find it let me know & I'll post it form there)

[JSP]

Thanks for all the info everyone. I have been taking it in but I'm living away from home at the moment and only have poxy mobile broadband. Oh the joy's of being married