Merc 15 hp running LOUDER

[Harbisls]

Last fall my 1989 Mercury 15 hp outboard started sounding like a chainsaw. I replaced the exhaust gaskets, thermostat, and water pump and it is still unbearably loud. What would cause this? How can I fix this?

 

[Sea Rider]

Welcome to Iboats,

That's a 2 stroke motor, right ? Re torque again the new base gasket, probably has ceded a bit with heat ? If that motor has never been decarboned during its entire life run 1/3 to 1/2 can of CRC marine carbon remover, the can specs are bit light, this procedure works much better : Check post 44 at this link :

Carburetor question on restoration I’m working on 1992 40 hp MSHQ Yamaha

On 2 stroke 2-3-4 cylinder motors won't find the spark plugs darken exact same as with 4 stroke ones, one or 2 will differ from the rest. The OP has installed new parts inside each carb along adjusting float's height to specs. If opening the fuel pump will surely find both rubber diaphragms...

forums.iboats.com

That gold product in a can will smooth out any motor, works for 4 stroke motors as well..

Happy Boating​

 

[Harbisls]

Welcome to Iboats,

That's a 2 stroke motor, right ? Re torque again the new base gasket, probably has ceded a bit with heat ? If that motor has never been decarboned during its entire life run 1/3 to 1/2 can of CRC marine carbon remover, the can specs are bit light, this procedure works much better : Check post 44 at this link :

Carburetor question on restoration I’m working on 1992 40 hp MSHQ Yamaha

On 2 stroke 2-3-4 cylinder motors won't find the spark plugs darken exact same as with 4 stroke ones, one or 2 will differ from the rest. The OP has installed new parts inside each carb along adjusting float's height to specs. If opening the fuel pump will surely find both rubber diaphragms...

forums.iboats.com

That gold product in a can will smooth out any motor, works for 4 stroke motors as well..

Happy Boating​

Can I spray the CRC in this opening?

 

[Faztbullet]

Yes you can spray it in there....on the noise look to see if anode above prop has came off

 

[Harbisls]

Welcome to Iboats,

That's a 2 stroke motor, right ? Re torque again the new base gasket, probably has ceded a bit with heat ? If that motor has never been decarboned during its entire life run 1/3 to 1/2 can of CRC marine carbon remover, the can specs are bit light, this procedure works much better : Check post 44 at this link :

Carburetor question on restoration I’m working on 1992 40 hp MSHQ Yamaha

On 2 stroke 2-3-4 cylinder motors won't find the spark plugs darken exact same as with 4 stroke ones, one or 2 will differ from the rest. The OP has installed new parts inside each carb along adjusting float's height to specs. If opening the fuel pump will surely find both rubber diaphragms...

forums.iboats.com

That gold product in a can will smooth out any motor, works for 4 stroke motors as well..

Happy Boating​

I finally got a new lower unit and tried the CRC stuff. I would barely spray into the carb and it would stall. It would restart after a few pulls. This happened 4 times and I gave up. How would SeaFoam work directly in the fuel float?

 

[Harbisls]

Welcome to Iboats,

That's a 2 stroke motor, right ? Re torque again the new base gasket, probably has ceded a bit with heat ? If that motor has never been decarboned during its entire life run 1/3 to 1/2 can of CRC marine carbon remover, the can specs are bit light, this procedure works much better : Check post 44 at this link :

Carburetor question on restoration I’m working on 1992 40 hp MSHQ Yamaha

On 2 stroke 2-3-4 cylinder motors won't find the spark plugs darken exact same as with 4 stroke ones, one or 2 will differ from the rest. The OP has installed new parts inside each carb along adjusting float's height to specs. If opening the fuel pump will surely find both rubber diaphragms...

forums.iboats.com

That gold product in a can will smooth out any motor, works for 4 stroke motors as well..

Happy Boating​

I finally was able to apply the CRC. At the moment the spray hit the carb the engine stalled. It would restart with about 4 pulls. This happened 4 straight times and I gave up. Would putting SeaFoam directly in the fuel line float work better?

 

[Sea Rider]

When spraying CRC decarbonizer through the carb ideally the motor must be left running geared on muffs at around the starting rpm setting and only spray one short shot at a time, let the motor recuperate the rpm loss, then spray another shot and so on, if sparying too long and too much the motor will stall, it's the nature of the product.



A better squirting procedure is to drill a tiny orifice right in middle of the carb's silencer and squirt CRC straight through the throat. If that motor has never been decarboned ever Sea Foam won't do much compared to CRC which it's a more effective near instant cleaning product...

Happy Boating