1998 yamaha 115 overheating

[CHEWBAKA1973]

Hello GentlePeople, I have a 1998 C115hp outboard that has been giving me some problems and was hoping someone could steer me in the right direction. I can run the engine up to about 3000 RPMs without any issues. Runs smooth and strong. If i push it over those RPMs occasionally the over heat warning buzzer will come on, the engine runs rough as crap but after letting it idle for a few mins or turned off i can run it below those RPMs all day.
the "pee" stream is strong so i believe the water pump is good although I have no replaced it in a couple years.
Question is.......... before i start throwing parts at the engine what could be causing this over heating?
Thermostats?
Poppet Valve?
Impeller?
obstruction somewhere?
dirt?
Gremlins?
thanks for the help.

[TownsendsFJR1300]

I would start with the basic's including a water pump kit, checking / testing the thermostat, poppet valve is easy to check...

While the thermostat is out, look in the block and see how much salt build up you have.

Even if flushed regularly, it's still 19 tears old and salt very likely is built up in the cooling passages. Overheating usually happens with somewhat higher RPM's but your jackets be more clogged...

Depending on what you find, (salt wise), there are some options before yanking heads (should the cooling passages be clogged).

Some reading:
http://www.yamahaoutboardparts.com/f...g-th19434.html

http://www.yamahaoutboardparts.com/f...m-th23666.html

http://www.yamahaoutboardparts.com/f...h27868-p2.html

If you have a flushing device in the power-head, you could technically do the procedure W/O yanking the LU but using a large pan under the engine to catch and re-circulate the mix.

A lazer temp gun, pointed at the cylinders, especially the lower ones, may show a higher temp from lack of water circulation.

IE, Some basic maintenance/ inspection is due..

[CHEWBAKA1973]

I would start with the basic's including a water pump kit, checking / testing the thermostat, poppet valve is easy to check...

While the thermostat is out, look in the block and see how much salt build up you have.

Even if flushed regularly, it's still 19 tears old and salt very likely is built up in the cooling passages. Overheating usually happens with somewhat higher RPM's but your jackets be more clogged...

Depending on what you find, (salt wise), there are some options before yanking heads (should the cooling passages be clogged).

Some reading:
http://www.yamahaoutboardparts.com/f...g-th19434.html

http://www.yamahaoutboardparts.com/f...m-th23666.html

http://www.yamahaoutboardparts.com/f...h27868-p2.html

If you have a flushing device in the power-head, you could technically do the procedure W/O yanking the LU but using a large pan under the engine to catch and re-circulate the mix.

A lazer temp gun, pointed at the cylinders, especially the lower ones, may show a higher temp from lack of water circulation.

IE, Some basic maintenance/ inspection is due..

Thx. I will look into it. I did this flush a few years back but at the time didn't replace the thermostats. Looks like it gunked up again. Time for another rydlyme flush.

[HarriesDGH]

As a religious fresh water flusher, this is what I uncovered when I changed my thermostats on my twin 115hp 2-strokes. Both engines were badly salted up

[CHEWBAKA1973]

As a religious fresh water flusher, this is what I uncovered when I changed my thermostats on my twin 115hp 2-strokes. Both engines were badly salted up

mine not quiet as bad as that but close. I dont get it. I guess these older yamahas will need a good Rydlyme flush every 3 years or so. oh well, ill do it this weekend and see what happens sunday when I run it.

[HarriesDGH]

mine not quiet as bad as that but close. I dont get it. I guess these older yamahas will need a good Rydlyme flush every 3 years or so. oh well, ill do it this weekend and see what happens sunday when I run it.

Me neither. I'm going to take the cylinder heads off next to see what lurks underneath, and around the pistons. I'm expecting a salt mine! I'll post some pictures if it's of interest.

[TownsendsFJR1300]

I'm also very anal about fresh water flushing. Both with the flush device AND RUNNING on the muffs (to open the thermostat). Below is how my PCV looked after ten years of service:



Internal build up internally isn't nearly as bad, but I didn't expect to see this ^^.

IMO, common sense, you run the engine in salt water, shut down to fish, beach, etc. Repeat MANY times over the years.

Every time you shut down, the engine is STILL HOT. Salt cooks/ builds up, water runs out. Repeat several times a day BEFORE you flush (at the end of the day).

Flushing does help, but the salt, cooks / builds up just from from normal operation daily and over time, even more...

[panasonic]

I'm also very anal about fresh water flushing. Both with the flush device AND RUNNING on the muffs (to open the thermostat). Below is how my PCV looked after ten years of service:



Internal build up internally isn't nearly as bad, but I didn't expect to see this ^^.

IMO, common sense, you run the engine in salt water, shut down to fish, beach, etc. Repeat MANY times over the years.

Every time you shut down, the engine is STILL HOT. Salt cooks/ builds up, water runs out. Repeat several times a day BEFORE you flush (at the end of the day).

Flushing does help, but the salt, cooks / builds up just from from normal operation daily and over time, even more...

Scott I believe you hit the nail right on the head wit that reply...

[CHEWBAKA1973]

Me neither. I'm going to take the cylinder heads off next to see what lurks underneath, and around the pistons. I'm expecting a salt mine! I'll post some pictures if it's of interest.

pictures are always of interest

[CHEWBAKA1973]

Scott I believe you hit the nail right on the head wit that reply...

Anyone use salt away once in a while?

[TownsendsFJR1300]

Anyone use salt away once in a while?

I just starting using it maybe 6 months ago...

I do my power-head flush, while coming up on the boat lift, then run the engine thru the muffs(to get to temp and open the thermostat).

Then while still running, turn on / apply the SA.
(Once you see "soapy water" exiting the engine, turn off the engine
(allow the SA to remain)

As for the results, don't know, way too early to tell.

I do the above procedure EVERY-TIME it gets used...

*The pic below, is where the above (nasty) cover bolts to (and was NOT cleaned at the time of the picture-yet):
No where near as bad as the cover. I did replace the rubber grommet (looked fine with no corrosion under it-I did
put a light layer of Yamaha's waterproof grease between the block and new grommet-(Some additional protector-ant)

[CHEWBAKA1973]

interesting. you dont flush out the SA after you run it through?

[TownsendsFJR1300]

interesting. you dont flush out the SA after you run it through?

Nope, that then defeats the purpose of using it..


From their site:
Salt-Away Applications ... :

Salt-Away is a water-based, non-hazardous, biodegradable solution and contains properties that dissolve, release and remove salt crystals from any surface. Water alone does not remove all the salt from a surface.

Use of Salt-Away does not correct past damage but will work to protect against salt corrosion and reduces costly repairs caused by salt.

Salt-Away breaks apart and removes salt accumulation with repeated use.

Salt-Away can safely be used on all metals, fiberglass, paint, rubber, plastic, chrome, glass, concrete, brick or any surface exposed to salt. Salt-Away, mixed with water, washes away the salt then leaves a protective film on surfaces until surfaces are again exposed to water or salt.

Special high-performing corrosion inhibitors in the product help protect metals from corroding if not rinsed off. Salt-Away will not strip wax or cause streaks or spots. It is easy to apply by using pressure or power washers, Salt-Away's special Mixing Unit, the ready-to-use spray bottles for smaller jobs, and by immersing items into a mixture of Salt-Away and water.

Salt-Away brings you the finest, safest, most reliable product in its category. These features have been standard since Salt-Away’s inception in 1994.

© Copyright, Salt-Away Products 1994. All rights reserved.


Non Hazardous. Contains no hazardous chemicals.
Non-Toxic. Safe to use around plants, children, pets and all living things.
Biodegradable. All ingredients biodegrade into the environment.
Environmentally Safe. Has no deleterious effects in the environment. Safe to discharge into normal drainage outlets connected to filter systems.
Water based.
Contains no petroleum products.
Contains no chemical solvents.
Does not react chemically or physically as an emulsifier on lubricants and coatings.
Inhibits rusting and corrosion.
Completely removes fresh salt.
Breaks down layers of salt accumulation.
Is chemically dissimilar to any competitive product.
Ingredients are the highest quality available.

[CHEWBAKA1973]

Nope, that then defeats the purpose of using it..


From their site:
Salt-Away Applications ... :

Salt-Away is a water-based, non-hazardous, biodegradable solution and contains properties that dissolve, release and remove salt crystals from any surface. Water alone does not remove all the salt from a surface.

Use of Salt-Away does not correct past damage but will work to protect against salt corrosion and reduces costly repairs caused by salt.

Salt-Away breaks apart and removes salt accumulation with repeated use.

Salt-Away can safely be used on all metals, fiberglass, paint, rubber, plastic, chrome, glass, concrete, brick or any surface exposed to salt. Salt-Away, mixed with water, washes away the salt then leaves a protective film on surfaces until surfaces are again exposed to water or salt.

Special high-performing corrosion inhibitors in the product help protect metals from corroding if not rinsed off. Salt-Away will not strip wax or cause streaks or spots. It is easy to apply by using pressure or power washers, Salt-Away's special Mixing Unit, the ready-to-use spray bottles for smaller jobs, and by immersing items into a mixture of Salt-Away and water.

Salt-Away brings you the finest, safest, most reliable product in its category. These features have been standard since Salt-Away’s inception in 1994.

© Copyright, Salt-Away Products 1994. All rights reserved.


Non Hazardous. Contains no hazardous chemicals.
Non-Toxic. Safe to use around plants, children, pets and all living things.
Biodegradable. All ingredients biodegrade into the environment.
Environmentally Safe. Has no deleterious effects in the environment. Safe to discharge into normal drainage outlets connected to filter systems.
Water based.
Contains no petroleum products.
Contains no chemical solvents.
Does not react chemically or physically as an emulsifier on lubricants and coatings.
Inhibits rusting and corrosion.
Completely removes fresh salt.
Breaks down layers of salt accumulation.
Is chemically dissimilar to any competitive product.
Ingredients are the highest quality available.

interesting. thanks
you ever use it under the cowling to rinse off salt spray and protect from corrosion?

[TownsendsFJR1300]

interesting. thanks
you ever use it under the cowling to rinse off salt spray and protect from corrosion?

No I haven't. Haven't had to. Never ran the engine the engine (underway) with the cowl off. I use LPS2: http://www.lpslabs.com/product-details/561 It should work (but again, I never had to).

This product helps keep the power-head free of corrosion. I may give it a spray 2x a year tops.

The engines been in service since 2007: