Little help please

[tgsx750f2000]

I have a 90hp Yamaha. The overheat alarm started going off on long runs then started going off on shorter runs. I had the water pump changed and went tested it today. Nothing changed. It goes off after about 5 minutes of running, I drop to idle for about 20seconds and it goes off. I felt the water coming out the pisser and it's not hot at all. Could it be the thermostat or maybe just a bad sensor?

["W"]

U getting oil

[tgsx750f2000]

It's a two stroke, and I mix it in the gas tank.

[jchief]

Change or remove the thermostat and see if that makes a difference

[chasin'tail]

How old is the motor? if it's close to 10yrs, think about the head plate galley areas being clogged up with crud. I have a 115 yamaha that did the same thing, chg water pump, checked thremo-stat. I pulled the heads off and found what a mech. said would be there. I cleaned the galleys, if you do it use plastic scrapers so you don't damage the metal. New head and water jacket gaskets and your back in business.

[tgsx750f2000]

Originally Posted by chasin'tail

How old is the motor? if it's close to 10yrs, think about the head plate galley areas being clogged up with crud. I have a 115 yamaha that did the same thing, chg water pump, checked thremo-stat. I pulled the heads off and found what a mech. said would be there. I cleaned the galleys, if you do it use plastic scrapers so you don't damage the metal. New head and water jacket gaskets and your back in business.

Changed temp sensor also and still have problem so now I'm leaning to what you said. Is it complicated are not to bad. I'm no mechanic but not an idiot either.

[Montauk17]

Originally Posted by tgsx750f2000

Changed temp sensor also and still have problem so now I'm leaning to what you said. Is it complicated are not to bad. I'm no mechanic but not an idiot either.

It's not hard to take the head and water jacket cover off. The problem is corrosion. If you feel the bolt getting tight don't force it. Soak the bolt and area in kroil oil for several hours or overnight,spray every couple hours. Putting it back together is easy just have to use a torque wrench. You should be able to find the torque specs online. When was the last time the water pump and thermostat changed?

[Gerald]

Originally Posted by Montauk17

It's not hard to take the head and water jacket cover off. The problem is corrosion. If you feel the bolt getting tight don't force it. Soak the bolt and area in kroil oil for several hours or overnight,spray every couple hours. Putting it back together is easy just have to use a torque wrench. You should be able to find the torque specs online. When was the last time the water pump and thermostat changed?

Very good advice.

If the bolt gets tight when trying to take it out, screw it back in some and then try backing it out again. Work the bolt back and forth, but don't "force" it to get it to come out or you may break off the bolt.

If it is still tight.....soak it some more and repeat.

If one of the bolts does not want to even start to come out...... try "taping" [give it a fairly firm hit] on the head of the bolt. The vibration of the "tap" can break the bolt threads loose and allow you to start unscrewing the bolt.

[tgsx750f2000]

Originally Posted by Montauk17

It's not hard to take the head and water jacket cover off. The problem is corrosion. If you feel the bolt getting tight don't force it. Soak the bolt and area in kroil oil for several hours or overnight,spray every couple hours. Putting it back together is easy just have to use a torque wrench. You should be able to find the torque specs online. When was the last time the water pump and thermostat changed?

Water pump was just changed right after this started and I removed thermastat and it still went off.

[Montauk17]

More than likely it is the head/water jacket then. I would have someone look at it first so you don't waste money.

[tgsx750f2000]

Originally Posted by Montauk17

More than likely it is the head/water jacket then. I would have someone look at it first so you don't waste money.

Montauk you don't think I should try and remove the the head cover myself?

[Montauk17]

Originally Posted by tgsx750f2000

Montauk you don't think I should try and remove the the head cover myself?

Sure,just hate to see you waste money if that is not the problem. You will need to buy new head and water jacket cover gaskets. If I remember right the head gasket is around 60 bucks and the water jacket gasket is around 20.

[Gerald]

The 3 gaskets for my 40 hp Force were more like $45, 3 or 4 years ago.

[Kajundave]

Originally Posted by chasin'tail

How old is the motor? if it's close to 10yrs, think about the head plate galley areas being clogged up with crud. I have a 115 yamaha that did the same thing, chg water pump, checked thremo-stat. I pulled the heads off and found what a mech. said would be there. I cleaned the galleys, if you do it use plastic scrapers so you don't damage the metal. New head and water jacket gaskets and your back in business.

I would have said a blown head gasket but...
[SIZE=3]Mine did the exact thing, it did it consistently on long runs, horn would sound, I would stop no steam, or extreme hot water exiting the engine, let it idle for 2/3 min and the horn would go off, it just kept getting more and more often. When or if you remove the heads you will probably notice one or two bolts loose, according to Yamaha you are supposed to re torque the heads after X- amount of hours, I re-torqued mine and the problem went away, after a few trips with no problems, I replaced the head gaskets anyway. This was on a Yama saltwater series 250hp[/SIZE]

[tgsx750f2000]

I finally figured out my problem today. It was my battery, must have had a short inside. Didn't show any problems until about a month ago, it started losing its charge. Hard to believe that a battery could cause a overheat alarm.

[Sea-Trac Offshore]

The 3 cylinder Yamahas are famous for build up in the water jacket. The plate on the side gets so much build up water cannot get through and cool at high speed. Seen it tons of times. It's not a hard fix. Yamaha and salt do not mix too well internally. The larger models I have seen many times while changing the thermostats that they had enough build up that when you go to clean it a hole would be eaten through block.


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