Older 25 HP 2 Stroke

[Ad88]

Son had out a cople weeks ago running fine said it just stopped.
New fuel, Carbs cleaned, new plugs. Will test compression this afternoon. If it's good whats the next step? ( I Know I need a Service Manual)

 

[Scott Danforth]

when was the last time the impeller was changed. look for signs of overheating

 

[Sea Rider]

Which brand motor might that be to start with ? If the motor was working fine could be a fuel or electrical related issue. Was the tank's air vent fully opened during operation ?​

Happy Boating

 

[MattFL]

To run motors need compression, fuel, air and spark. One of those is missing, your mission is to figure out which one.

 

[Ad88]

tohatsu 25
Water pump replaced last year
Had a game tonight didn’t get to check the compression, I hope that’s not it

 

[Sea Rider]

The compression will not fail suddenly, could happen if the motor achieved a severe instant head gasket blow out, which didn't happened, right ? Or probably your son run the motor without adding 2 strokes oil and seized the motor up ? If turns, it's any other issue which must be well diagnosed.

Happy Boating​

 

[Ad88]

Thanks, it had oil in the gas. What would I need to look for in blown head gasket

 

[MattFL]

Compression. Possibly water in the cylinders. Check the easy stuff first though, such as spark. Maybe the lanyard got pulled or a wire came loose, etc..

 

[Ad88]

I need to take off wire harness and clean it up and make sure connections are good. Tested spark with the tool that looks like a screw driver with a snap on plug cover coming out of handle, both plugs showed spark. Trying to keep it simple

 

[MattFL]

You've got spark; a overly simple compression test is shoot some starting fluid or something similar into the open carburetors and see if it will fire. If it starts for a brief moment then stalls, then compression is probably OK and you're missing fuel. If it won't fire, then check compression. You can use something like WD-40 as well if you happen to have it there, the propellant is flammable, but starting fluid works the best.

 

[Sea Rider]

What's the cond of the current motor, has low, medium or high run hours ? Was it possible to start it back after unexpectedly dropped dead ? Disconnect both kill cord switch ends, will the motor start when puling the rope hard ? If starts will need to shut the motor pulling out the choke knob. Check that all ground terminals are shinny along where they connects to.

If used in salt water, would you say there's white salt lines formation around the contour of the cylinder head ? Are the spark plugs tips rusty aside from being darkened. WD-40 it's no good for spark plugs, just squirt some small shots of 50:1 mixture into the cylinders.

Happy Boating​

 

[Ad88]

Thanks guys will try the kill switch disconnect. It’s an electric Start
Son said when it died it wouldn’t restart. Plugs were in good shape but went ahead and replaced

 

[Sea Rider]

Thanks guys will try the kill switch disconnect. It’s an electric Start
Son said when it died it wouldn’t restart. Plugs were in good shape but went ahead and replaced

Disconnect both cables at motor's end and start the motor electrically and see what happens ? Which Tohatsu 25 HP model will it be ? M25C2/C3 ? If the motor counts with a fuse, check that out too.

Happy Boating​

 

[Ad88]

Bad news boys 145Psi on the bottom 25 psi on the top. Looks like it was ran hot. Pulled thermostat cover and there’s trash down in there. I guess it’s scrap now? Idk

 

[Ad88]

Ideas on fixing. I’m slightly mechanically inclined, don’t mind doing some of the tear down myself if it’s worth messing with. Son will split cost. It’s not a motor that we use a lot but wouldn’t mind a project to work on until the fish start biting lol. Thank y’all for your input.

 

[Sea Rider]

If that's a salt water motor remove the powerhead from the pan, remove exhaust covers, cylinder head, thermo cover. Inspect the cylinders for scratches, scores, if clean and perfectly round install a new head gasket along pan, exhaust and thermo cover gaskets as well. Take advantage to clean all salt formations, crusts found in the entire water circuit for motor to cool as when new. Replace thermo if excessively salt crusted, rusted, shot. Can pass that 25 to a 30 HP for peanuts cost.

Never seen any Tohatsu motor with such uneven compression, that's why its a must have at hand a compression meter for fast troubleshooting and avoid wild guesses...

Happy Boating
​

 

[Ad88]

It was was used in the marshes of South Louisana as a crawfish boat before I bought it. It’s only seen freshwater since then but I’m sure there are deposits in there somewhere. The restrictor plate had been removed also. Going to tear down and clean everything. If everything is clean in Cylinders what part would you suggest replacing

 

[MattFL]

You have to take the head off and inspect it to see what really needs to be replaced. If the cylinder looks bad (scratched up), look carefully to see if it's actually scratches or if it's metal bits from the piston embedded on it. If it's piston bits, and if the cylinder is plated (very common) you can sometimes clean the aluminum piston bits off of the cylinder with acid and the result can be serviceable as-is, just replace the piston. You won't know until you get it apart to look at it. Years ago my buddy had a V6 Evenrude that overheated and melted a piston after the previous owner tried to drive it through a sand bar, and this is how it was fixed.

 

[Sea Rider]

Won't know the cylinders condition untill the head is removed, report if was found shot or in good shape to go from there. Better clean all the water passages removing what indicated, installing new base, exhaust covers, cylinder, thermo, thermo gaskets will be the best investment ever. Removing the 25 air restrictor and installing a 30 HP one it's half of what the motor needs for a full 30 HP conversion. Which prop is currently installed, is it a 13 pitch ?

Will be interesting to find what kind of deposits the motor has collected in the entire water circuit over the years working in the marshes ?

Happy Boating​

 

[Ad88]

Won't know the cylinders condition untill the head is removed, report if was found shot or in good shape to go from there. Better clean all the water passages removing what indicated, installing new base, exhaust covers, cylinder, thermo, thermo gaskets will be the best investment ever. Removing the 25 air restrictor and installing a 30 HP one it's half of what the motor needs for a full 30 HP conversion. Which prop is currently installed, is it a 13 pitch ?

Will be interesting to find what kind of deposits the motor has collected in the entire water circuit over the years working in the marshes ?

Happy Boating​

Thank you will start tear down Sunday