Engine won't start - 15HP Mariner Marathon 2 stroke

[jeffstevens763@g]

is there not a rev limiter on these? and is the water just from the tell tale hose being split?

[ben324]

I have had another look at it this morning. When it is in neutral the propeller turns freely. When it is in gear the propeller still turns freely but with a slight amount of resistance.

The water leak is coming from part of the case that seems to have come away and the previous owner had glued back together

[Nasher]

Ben

Can you take the prop off and try just turning the prop shaft with it in gear.

I can't remember what method these engines have as a safety feature to save the gearbox if you hit a rock with the prop, but it could be either the shear pin has sheared, or even the centre of the prop turning in the body.
But you do need to eliminate the prop before condeming the gearbox etc.

From what your friend told me on the phone it sounds like this engine has been apart before, and whoever did it might not have even replaced the shear pin if fitted with one.

That broken casting is going to need fixing obviously, it might be OK with epoxy but really needs TIG welding.

As had been said, you might need to start considering a newer engine to go with your smart looking boat.

Nasher.

[Max...]

Referencing posts 4 + 7. What was the history? Do you have any comebacks? It's really not a engine even if you get going I'd trust my time at sea with - you can't just pull over at the side of the road.

Guessing you did not see it running before purchase.

[ben324]

I have taken the propeller off and it turns out that safety point rubber bushing has completely gone. At least it isn't something internal.

I feel like I am making complete beginner mistakes.

I do not know how to chose a new propeller. I am most likely going to make another begginers mistake in chosing.

[Nasher]

Ben

Nobody is born with this knowledge, and on the whole people on here are very tolerant of questions from new guys.

The current prop size should be stamped on one of the blades or hub.

There are lots of ways to work out what prop size you need, but in the end it comes down to trying a couple of different sizes around the size the calculator gives you.
I'm sure somebody will be along soon with some recommendations.

you'll probably end up buying a couple off ebay to try.

But you'll need to sort out that broken casting somehow first.

Nasher.

[Fenlander]

Don't know the diameter of yours but it should be marked on it or just measure or look at a parts listing. Re the pitch a 9" is a pretty safe bet for a 15hp on a SIB with average load. In your case with other jobs to do on the engine I might be looking at the budget ones on Ebay.

You will need to check how many teeth on the prop spline too.

[Big Al C]

Forget the fact your engine could be toast.... where the f### are your life jackets.. ..
Not sure if you have one on. . But your mate doesn't in the video.
Sorry for the rant.....

[Allye]

Originally Posted by Big Al C

Forget the fact your engine could be toast.... where the f### are your life jackets.. ..
Not sure if you have one on. . But your mate doesn't in the video.
Sorry for the rant.....

Apology accepted, you shouldn’t judge others on your own ability, or there lack of. I rarely if ever wear one. It’s cumbersome and hinders me in the water. I surf, free dive, ocean swim, body surf, wake board, cliff jump etc!

Come down off your high horse and let people do what they want

[spartacus]

Play nice folks.

This 15hp rebuild can be done.

Things I would be looking to do - before I venture out again.

1/ New propeller obviously (aluminium). Opportunity to grease the prop-shaft and fit a new split pin on the castle nut

2/ New gear oil - I'd love to see what comes out. Fit new fibre washers on drain and fill screws. Yamlube or similar

3/ Clean fuel filter on engine

4/ Renew starter rope - going with condition of other things this engine has had a hard life. The last thing you want is for the starter rope to break

5/ Renew impeller. I'd want a proper look of the waterpump

6/ Check thermostat and clean (buy a new gasket first), hopefully you can reuse theromstat

7/ Repair the casting. As suggested, TIG weld is the way to go, epoxy is short-term solution given water and vibration

[Big Al C]

I haven't got a problem with people doing what they want..... but if the worst was to happen, with all this crap that's going on in the world at the moment some one else has to come out and put themselves at risk.
I've never got it to a debate on here before..... I usual sit back and watch every one else give each other abuse. But don't expect the Life boat or Fire Service crews to welcome you with with open arms and not give you a hard time.
And before you come back at me..... I've been there.... had the job of retrieving dead bodies from all sorts of water incidents over the years.
I'll get off my high horse now.....

[Coastie]

Originally Posted by Fenlander

Don't know the diameter of yours but it should be marked on it or just measure or look at a parts listing. Re the pitch a 9" is a pretty safe bet for a 15hp on a SIB with average load. In your case with other jobs to do on the engine I might be looking at the budget ones on Ebay.

You will need to check how many teeth on the prop spline too.

I’ve a Mariner 15hp 2 stroke on a 14 grp boat- I’ll take a look at the prop size and let him know. Could be a starting point if looking for replacement

[Fenlander]

Yes... if's a 9" pitch Coastie it will be a good starting point.

[Allye]

Originally Posted by Big Al C

I've been there.... had the job of retrieving dead bodies from all sorts of water incidents over the years.
I'll get off my high horse now.....

As have I. Knowing a few LB crews and CRT’s I guarantee they’d be happy for the job.

[ben324]

After a lot of messing with the engine I have managed to get it working. Luckily the propeller was slipping and the gearbox was not broken.

https://www.youtube.com/watch?v=FLCeu-225zE

The boat only went 20mph. I have been told by many people that it should go 30mph. I do not know what is causing the lack of power. Is there anything I can do to get it going faster?

Also the engine cuts out every now and then. Sometimes even when going full speed. The engine is very hard to start, rather scary trying to start it when out at sea.

[69cmw]

Originally Posted by ben324

The boat only went 20mph. I have been told by many people that it should go 30mph. I do not know what is causing the lack of power. Is there anything I can do to get it going faster?.

Anyone telling you it will do 30mph is talking crap unless it’s on a trailer behind your car [emoji848]

20mph is good going

[jeffstevens763@g]

craigs right my mercury 365 would do 22 knots with a 25 hp about 25 mph you going well IMO you need to get that engine serviced with a good carb clean or even a new one for piece of mind surmising everything else has been done

[Max...]

Originally Posted by ben324

The boat only went 20mph. I have been told by many people that it should go 30mph. I do not know what is causing the lack of power. Is there anything I can do to get it going faster?

30mph?!!?

Typical SIB with 15 Merc and lightish typical load then WOT you'll be at 16 to 18 kts tops.

[A1an]

If I was venturing out in salty water I'd be looking to buy a more reliable engine than you currently have.

Just my tuppunce worth.

[Coastie]

Originally Posted by Fenlander

Yes... if's a 9" pitch Coastie it will be a good starting point.

Confirmed, mines a 9 inch. Hopefully he gets sorted soon.