Over heating

[JWK]

I own a 1985 70hp yamaha and last week several things happened on the lake.The first day the red light on the oil gauge started to come on but the oil tank was full. I replaced the oil sensor and bleed the oil pump for air. I returned to the lake the next day and the red light was now off and the gauge stayed green but know the buzzer went off and I lost rpm. Water was coming out of the pee hole at this time but suddenly stopped. I shut the motor off and *****ed back to the ramp. Can you tell me if the impeller goes bad does it shut down the water alltogether from coming out of the pee hole? I don't think it run to hot so how much do I replace, just the impeller or is there a kit I need to replace. I did try and restart the motor back at the house with the earmuffs just to make sure it was doing the same as on the lake. The buzzer did not come on as it cranked up but still no water. I did turn it off just as I seen no water coming out. What can anyone suggest is wrong and what should I replace.

[jonp]

Hello,

How hot did the engine feel when this happened? were you able to touch the block? There is a thermal switch mounted on the block which activates the alarm system.

Does sound like your impeller (water pump) may have gone south. I have had a few outboards over the years with odd impeller issues, (including 2 Yamahas) My small 25 HP yamaha pumped water with 3 of the 5 vains broken off the impeller. My 90HP seemed to pump plenty of water but the alarm would off after 15-20 minutes. Turned out the the previous owner the engine changed the impeller but left a piece of the old one stuck in the water tube... This drove us nuts.

Until recently I had a V6 merc, had not changed the impeller in a few years, last season I noticed the temp rising really high almost into the red zone on the gauge. Pumped lots of water.. So I changed the impeller. Interesting about this was the impeller looked perfectly fine... I was prepared to start fooling with thermostats. The new impleller did the trick. The old one was just weak but looked OK.

One other simple thing, check the pee hole and line for a blockage. Could be clogged. I use a piece of # 14 electical wire to stick up there. If no water is pumped, then I would start by replacing the water pump. Check for junk in the water tube. If it does not work, then replace the thermostats. Also get shop manual.

Good Luck Jon

[Ken]

JWK,
The water pump pilot hole discharge, aka "pee-stream" is just an indication that the water pump is working, but does not tell you how well.
Also, the pilot hole can get clogged with debris to the point that no water is coming out.
What I usually do is disconnect the hose from the plastic nipple that is snapped into the lower cowling and tape it over the side pointing downward and then run the motor on earmuffs to check the stream. Also, at this time, you can run a wire or mono thru the nipple and clean out.
Now, after having said all of that, it does sound like your water pump has gone out. If it has been at least three years since last water pump repair, I would go ahead and drop the lower unit and install a water pump kit.
Also, check the water pump tube that leads from the pump up to the motor head for any restrictions, especially if any part of the impeller is missing.
Boats.net, sponsor of this forum, is a good source for parts - great prices and service.
You can order a Yamaha shop manual online at www.yamahapubs.com.
Good luck [img]smile.gif[/img] ,
Ken K