1994 Yamaha 115HP 2 Stroke Alarm at high rpms

[ausnoelm]

Not sure what that will prove, the engine doesn't know whether you mixed oil in the fuel or not.

[Jason2tpa]

And of course you might be able to check if oil deficiency is the problem by adding 50 to 1 oil to your tank ( mix a small amount if you can empty your tank somewhat), then run to see if alarm doesn't activate.

Not completely following you here ^^^. Remember he doesn't have gauges. He also stated borh reserve and main oil tanks are sufficiently full. So if determined the alarm he's experiencing is the low level oil alarm, this would then point to a bad oil level sensor in reserve or main tank.

[zenoahphobic]

Not completely following you here ^^^. Remember he doesn't have gauges. He also stated borh reserve and main oil tanks are sufficiently full. So if determined the alarm he's experiencing is the low level oil alarm, this would then point to a bad oil level sensor in reserve or main tank.

I'm not that good at explaining sometimes.
Engine seizure was mentioned by Panasonic. So I thought it is possible that the alarm is still an overheat alarm if it is caused by insufficient oil getting into the engine. Obviously there is some oil getting in as no oil will seize the engine in a very short time. Thinking three steps ahead to possibly avert damage, it may be a less technical way of diagnosing a problem/ eliminating oil as the problem (more to oil than an alarm and the oil tanks being full) that someone might be more comfortable doing and understanding.

[TownsendsFJR1300]

How old EXACTLY is the water pump and did you replace it with an entire kit or just impeller?

Did the WP impeller housing show ANY signs of heat damage?

Lastly, you mentioned fresh water use only. Has that been it's entire life or how long?
I ask in that your issues mimic salt water crud build up in the head/cylinder. -A new water pump (even flowing great), won't fix a clogged cooling system/block/head.

As noted earlier, at high RPM's, there's not enough water flow for the amount of heat the engine is making (with a clogged cooling system).

[99yam40]

There are some places where even fresh water has lots of minerals in it, and they build up in the cooling passages also.

best thing would be to identify what the alarm is 1st. then find a way to fix it

[ezzrider]

I pulled boat back out of lake and checked to make certain both oil reservoirs, engine and remote were full and they were. I checked all connections to assure nothing loose. I then hooked up the ear muffs, started the water full force and cranked up engine. For some reason the water coming out of the pee hole was not as strong as in the water even though I had the hose running full force and was hooked up correctly over the grates. In neutral the alarm went off fairly soon. I turned off engine and noticed the heads were very hot. We replaced the water pump about a year ago and only use in freshwater. Now I wonder if my issue is overheating. Why would this overheat out of the water with the muffs hooked up and not in the water at idle? Next step a new impeller?

[ezzrider]

How old EXACTLY is the water pump and did you replace it with an entire kit or just impeller?

Did the WP impeller housing show ANY signs of heat damage?

Lastly, you mentioned fresh water use only. Has that been it's entire life or how long?
I ask in that your issues mimic salt water crud build up in the head/cylinder. -A new water pump (even flowing great), won't fix a clogged cooling system/block/head.

As noted earlier, at high RPM's, there's not enough water flow for the amount of heat the engine is making (with a clogged cooling system).

Sounds reasonable. I have owned this boat since 2005. It was used in saltwater before I purchased but was stored in a high and dry and flushed after each use. I used it a couple of times in saltwater many years ago but has been nothing but fresh water for at least last 5 or 6 years. This motor is on a 24' pontoon boat. Since I have out of water now what is the best (easiest) way to check for clogged water passages or can I just run something through the engine like Salt Away? Our lake is an extremely clear water lake.

[dray0151]

I think several on here would tell you even with flushing every time after use in salt water, crud will still build up. Have you checked your thermostat, don't remember if you mentioned that. I think before pulling apart things I would try flushing with one of the mixtures talked about here and see if it takes care of your issue, but that is just me.

[TownsendsFJR1300]

Plus one ^^^. Pull the thermostat, maybe a lower anode, pressure relief valve and check for salt build up...

That should give you an idea of what the innerds look like.

The WP being a year old is about due (by the book) for replacement.

I'd do a WP KIT (a little more $ but worth it)-basic maintenance before tearing down anything major.


IME, with the PO using in salt water, every time you run, get the engine hot and turn off (say to fish), water runs out of the engine and salt
cooks/attaches inside the engine.

I boat in brackish/salt water and flush (extensively). Still found a fair amount of salt in the thermostat/anodes, etc after approx. 10 years of use..

[zenoahphobic]

I pulled boat back out of lake and checked to make certain both oil reservoirs, engine and remote were full and they were. I checked all connections to assure nothing loose. I then hooked up the ear muffs, started the water full force and cranked up engine. For some reason the water coming out of the pee hole was not as strong as in the water even though I had the hose running full force and was hooked up correctly over the grates. In neutral the alarm went off fairly soon. I turned off engine and noticed the heads were very hot. We replaced the water pump about a year ago and only use in freshwater. Now I wonder if my issue is overheating. Why would this overheat out of the water with the muffs hooked up and not in the water at idle? Next step a new impeller?

Not discounting that your water pump is weakening, in answer to your question, often earmuffs flushing produces a smaller stream and hence if weak enough after some time sets the overheat alarm off, despite ample hose pressure. These pumps work best fully immersed in water.

[ezzrider]

Not discounting that your water pump is weakening, in answer to your question, often earmuffs flushing produces a smaller stream and hence if weak enough after some time sets the overheat alarm off, despite ample hose pressure. These pumps work best fully immersed in water.

Thanks. Going to put a trash can under motor and fill with water. I have however used the ear muffs in the past with no alarm issues. The water pump was replaced with a completely new water pump and not a kit about a year ago. I did not replace had a friend who is a marine mechanic replace but he is not available now. I am going to look at the thermostat. The manual says there are two of these on this motor? Never checked the thermostat myself.

[rodbolt17]

either it is overtemping OR consuming oil faster than it can transfer.
when was the last time the remote oil tank filter got serviced?

[ezzrider]

either it is overtemping OR consuming oil faster than it can transfer.
when was the last time the remote oil tank filter got serviced?

I have never serviced the remote oil tank beyond just inspecting and I have owned since 2005. I inspected yesterday to assure everything was hooked up but nothing beyond that. This pontoon boat sits in our freshwater lake and is used just to putz around the lake several times a week. No real long runs at full speed. Not used in salt water for years. Not much use really.

[Captn Dave]

I'd start with the thermostats.

[ezzrider]

I'd start with the thermostats.

Yep. Looks like two thermostats. Hopefully the covers come off fairly easy. Do not believe they have been checked in years. I pulled both out. One side looked OK and other had some gunk but neither were real bad. Going to replace anyway as one was in real tight and rubber tore on one taking out. Off to boat place to get new thermostats and gaskets.