Outboard

[jbrock]

I know I’ve been posting quite a bit. Thanks for all of the advice. I do appreciate it. Long story short I overheated my Mercury 8 HP 2 stroke and now it won’t start. I left it running with sea foam in the gas (was idling beautifully) and when I came back the engine was off and steaming, and all the water in my container was gone—sprung a leak. To add insult to injury the pull cord snapped off about 6 inches from the handle when I was trying to get it to start. I think the engine is cursed and am contemplating getting a replacement. If I do decide to try and repair this one do I start with the water pump, compression test, anything else (once I replace the cord of course)? Any guidance would be appreciated. If I decide to get a replacement what do people recommend for a Macgregor 25? How much HP is enough? I think the original engine before this one was a Johnson 6 HP. Thanks!

 

[Michael Davis]

I've never done that to a gas engine but I did break a V-belt on a Perkins 4-108 once that ran at 2200 RPM until it seized. Starter would not move it. Replaced V-belt and sailed slowly for a couple of hours until the engine cooled. Tried starting again and away it went. Ran for several years after that and eventually sold that boat. May you be so lucky.
Small motors are not that difficult to rebuild so give it a shot, you have nothing to loss. Water pump sounds like a place to start.

 

[Michael Davis]

If it doesn't turn over with a new pull cord you might start by pulling the head and giving the top of the piston a gentle tap.

 

[sbcwolff]

We love our Tohatsu sailpro 6hp for our mac26s. More than enough power, and super dependable.

 

[RussC]

I started with an old 6hp Johnson, which worked fine for several years. now I have a like new 4hp Johnson 2 cycle and it's just as fast as the old 6hp was, but uses a lot less fuel.

 

[timebandit]

First things first. Pull the cover and the spark plugs. Lay the motor so the plug holes are up and pour some sea foam in the plug holes and try rocking the motor back and forth using the flywheel. Chances are the pistons seized and this should free them. You may have to let it sit overnight.
If you get it to turn over install the plugs, fix the rope and mix up some synthetic two stroke oil about 25 to 1 and allow it to run for about an half an hour. Make sure the pump is working and that there are no bad sounds. I would change the impeller just in case and the plugs too.

 

[rgranger]

We love our Tohatsu sailpro 6hp for our mac26s. More than enough power, and super dependable.

I have the same motor. Almost always starts on the first pull.

 

[jbrock]

First things first. Pull the cover and the spark plugs. Lay the motor so the plug holes are up and pour some sea foam in the plug holes and try rocking the motor back and forth using the flywheel. Chances are the pistons seized and this should free them. You may have to let it sit overnight.
If you get it to turn over install the plugs, fix the rope and mix up some synthetic two stroke oil about 25 to 1 and allow it to run for about an half an hour. Make sure the pump is working and that there are no bad sounds. I would change the impeller just in case and the plugs too.

Thanks, Timebandit. Sage advice as always.

 

[rgranger]

Wait... first you need to understand why it over heated. Is your impeller toast?

 

[Captain Ron 18]

Before you lay your hard earned money down for a new ob, please follow the advice of timebandit and troubleshoot yours. I’ve never owned a Merc, but if you’re mechanically inclined, you might find it’s a reasonably simple matter. I would definitely check that impeller, too, since you were running it dry for a while.

Should you need to move on, I just checked the builder’s paperwork that came with the boat - says 10hp is the max. When I bought Water Music in 1985 (new), I used a 1970 9.5 Johnson short shaft. Plenty of muscle when I needed it, and no problem lifting it by myself. I did end up long-shafting it which fixed the prop-out-of-the-water problem when I was in waves on Chesapeake Bay. I upgraded to a 9.9 Evinrude long shaft in 1998 and it’s still going strong. (I can’t lift this one by myself...). If I weren’t sailing where I do, where significant storms can blow up pretty quickly and make life extremely difficult, I would use a smaller motor like the other folks who have posted here, but it’s nice to have the oomph to get out of harms way if I need it.

Good luck!

 

[Tsatzsue]

Dito on pulling plugs. If it is frozen. Mystery oil or sea foam or a combo will help. Merc heads are not user friendly. On my Johnson then can be taken off to get at the head gasket and pistons easily. Not the Merc. Once free, if frozen, you will be able to feel the compression of lack of by pull starting. If it feels ok, and runs replace the impeller. Probably $15 in parts band a couple hours of work. Run it with at with 50/1 and sea foam and go for it. I know the newer Mercs have a temperature safety to stop the motor from catastrophic overheating. You might be ok.

 

[Tsatzsue]

Check out Leroy's Ramblings on line. This guy is the OB genius. I did a complete overhaul with his technical help.

 

[jbrock]

Wait... first you need to understand why it over heated. Is your impeller toast?

I don’t know that it overheated. I just know that I came back to it and there wasn’t nearly enough water in the trash can to cover the intake, and the engine had stopped. It wouldn’t restart after refilling the can. I tried again the next day and it would turn over but nothing else. Then I snapped my cord—not because the engine was seized but because the rope was old and starting to fray. It was running beautifully right before my major screw up. I ordered a new impeller assuming that it will need replaced regardless (just because of time since last replacement alone). I had just put new plugs a week or so before all of this. Do you think there’s still value in replacing the plugs? Any other suggestions? Thanks, everyone.

 

[jbrock]

Dito on pulling plugs. If it is frozen. Mystery oil or sea foam or a combo will help. Merc heads are not user friendly. On my Johnson then can be taken off to get at the head gasket and pistons easily. Not the Merc. Once free, if frozen, you will be able to feel the compression of lack of by pull starting. If it feels ok, and runs replace the impeller. Probably $15 in parts band a couple hours of work. Run it with at with 50/1 and sea foam and go for it. I know the newer Mercs have a temperature safety to stop the motor from catastrophic overheating. You might be ok.

Sounds good. Thanks! I really don’t think it’s seized. It was pulling to start and turning over normally after the incident. Just wouldn’t start. I’ll certainly change the impeller. Not sure what else to try to get it to start.

 

[Tsatzsue]

You might have warped the head. Once you get the chord fixed and it in water. It should start. If it sputters out pull the plugs. Any milky residue or actual water will be the head gasket. The exhaust/ water box gasket is the other one that can let go. That one was a bitch on my Johnson. If I recall the Merc head gasket was almost not serviceable due to the design. Again Welcome to LeeRoy's Ramblings is the best place to read about all things OB.

 

[Tsatzsue]

What are the mod/ser #s?

 

[CaptVR]

First things first. Pull the cover and the spark plugs. Lay the motor so the plug holes are up and pour some sea foam in the plug holes and try rocking the motor back and forth using the flywheel. Chances are the pistons seized and this should free them. You may have to let it sit overnight.
If you get it to turn over install the plugs, fix the rope and mix up some synthetic two stroke oil about 25 to 1 and allow it to run for about an half an hour. Make sure the pump is working and that there are no bad sounds. I would change the impeller just in case and the plugs too.

CaptVR here, I agree with everything this gentleman said, except, SeaFoam, SeaFoam is great at desolving deposits bur not much in lubrication, With 60 years of experience and many frozen engines, I would put a bit of Marvil Mystery Oil, much more lubratricity and it creeps great. Depending where the pistons stopped at, fluids might run out of intake and exhaust ports, you may have to put it in an oil can and every 20-30 minutes, put a fresh squirt in the spark plug hole. Do that over about a 4 hour period. Wish you luck, as someone else said, these small engines will take a lot of abuse. CaptVR

 

[Ms Hope]

We love our Tohatsu sailpro 6hp for our mac26s. More than enough power, and super dependable.

I’m looking at getting a new outboard for our 26D. Do you sail in tidal waters with the 6 hp?

 

[Tsatzsue]

I would go with no less than a 10hp in any ocean or tidal waters. Pounding into a headwind and chop id difficult enough. Throw in tidal current and you will need all of it. Trust me, you will be glad you have it when you need it most. My Johnson 9.9 sipps gas too. We have it all here in New England. I would go with no less that a reliable 10hp.

 

[Ms Hope]

I would go with no less than a 10hp in any ocean or tidal waters. Pounding into a headwind and chop id difficult enough. Throw in tidal current and you will need all of it. Trust me, you will be glad you have it when you need it most. My Johnson 9.9 sipps gas too. We have it all here in New England. I would go with no less that a reliable 10hp.

Thanks for the reply one other question- my transom well measures 20” to the center of hull. Would you use the 20” long shaft as indicated by specs or go with a 25”? The old motor I had was a 25” and the Rudder would occasionally hit the prop when doing tight maneuvers. Thanks again