1989 Yamaha 200 HP (Overheating)

[lasvegaskid]

1989 Yamaha 200 HP
I wish I wasn't here posting but I am. I just changed the shift shafts on my 2 engines. That was a project, but went smooth.
My Starboard engine all of a sudden, is sounding the alarm horn. I changed both water pumps & thermostats. I checked the engine temps with a temp gun. One is 132 the other is 213. This is at idle after about 10 minutes with the muffs and hose. It is a steady horn. I had no problem, when they were in the water. I don't know what temp it was running in the water, but the horn never went off. I know the muffs don't give as good a supply of water, but why such a difference in the 2 engines?
I rechecked the water pump, and it's fine.
I also pulled out the pressure valve that was a little corroded, but not that bad. I'm not sure what it's function is? There is also a good stream of water coming out of the small hose. I saw the buildup on heads pictured on one thread, (Link Below) but can't believe, I would have that problem? Maybe I do. I'm about to pull the heads today, but will wait until Wednesday. I need to winterize the engines, I'm in Ct. and it's starting to get cold at night.
I don't need another problem, on top of this one. I know Rodbolt is the expert on this stuff. So I hope someone can help me. Thanks in advance, for the advice. Bob I wish everyone a Happy and safe Thanksgiving http://www.sunpac.zoomshare.com:80/...e/trebuchet.css&css=/lib/style/type_album.css

 

[lasvegaskid]

Re: 1989 Yamaha 200 HP (Overheating)(Maybe Fixed)

Re: 1989 Yamaha 200 HP (Overheating)(Maybe Fixed)

I think I solved the problem. I panicked to quick. I pulled the thermostats out, and ran the engines without them and the covers. For about 2 minutes no water coming out. Then I went and squeezed the muffs tight, and the water flowed out like Niagara Falls. I checked the temperature and it stayed at 132 muffs tight. When a let the muffs go, it started to rise. Case in point, Loose Muffs Sink Engines. Now I can lol............. I'm going to put it back together, and try it. I will post again. Thanks for being here, for help. Bob

 

[lasvegaskid]

Re: 1989 Yamaha 200 HP (Problem Solved)

Re: 1989 Yamaha 200 HP (Problem Solved)

Just like I said, the muffs were not tight and water was leaking to the side.
I used my big channel locks and tightened the muff. Ran the engine 15 minutes, temperature stayed at 132. Does anyone know if there are some add on temperature gauges? It would be nice to know the exact temp of the motors. I used to have them on my race cars. I would need to know where the sending unit would be installed? Thanks, Bob

 

[Asainz320]

Re: 1989 Yamaha 200 HP (Overheating)

Im glad you found out what it was. Same thing happened to me. It was frustrating.

 

[BruceAML]

Re: 1989 Yamaha 200 HP (Overheating)

Did you install a new pressure control valve and spring?

 

[lasvegaskid]

Re: 1989 Yamaha 200 HP (Overheating)

Did you install a new pressure control valve and spring?

No I haven't replaced the valve or spring. What is the purpose of it.
I understand an auto with a closed system, but an open system
where is the pressure. I can't see anything in the service manual about it's function. I will look further. I will probably replace it. I'm going to start another thread on a motor trim and tilt problem. Thanks, Bob

 

[rodbolt]

Re: 1989 Yamaha 200 HP (Overheating)

minimum block pressure is 11 psi or so.
without a method to control water pressure at all RPM and the t-stats constanty opening and closing either pressure will go above 30 psi or below 11 psi creating issues
I have asked twice at what RPM this occurs yet you wont say.
forget anything you thought you knew about automobiles.
at low speeds the indication of a stuicking/non sealing valve is low speed overheat and fine above 1200 RPM or so.
excess water pressure is dumped into the exhaust stream
I have never seen the valve or spring go bad but the corrosion will displace the grommet and cause sticking issues that allow the valve to bleed off to much pressure at idle and not allowing the top of the block to fill with water.

 

[lasvegaskid]

Re: 1989 Yamaha 200 HP (Overheating)

1989 Yamaha 200 HP
I wish I wasn't here posting but I am. I just changed the shift shafts on my 2 engines. That was a project, but went smooth.
My Starboard engine all of a sudden, is sounding the alarm horn. I changed both water pumps & thermostats. I checked the engine temps with a temp gun. One is 132 the other is 213. This is at idle after about 10 minutes with the muffs and hose. It is a steady horn. I had no problem, when they were in the water. I don't know what temp it was running in the water, but the horn never went off. I know the muffs don't give as good a supply of water, but why such a difference in the 2 engines?
I rechecked the water pump, and it's fine.
I also pulled out the pressure valve that was a little corroded, but not that bad. I'm not sure what it's function is? There is also a good stream of water coming out of the small hose. I saw the buildup on heads pictured on one thread, (Link Below) but can't believe, I would have that problem? Maybe I do. I'm about to pull the heads today, but will wait until Wednesday. I need to winterize the engines, I'm in Ct. and it's starting to get cold at night.
I don't need another problem, on top of this one. I know Rodbolt is the expert on this stuff. So I hope someone can help me. Thanks in advance, for the advice. Bob I wish everyone a Happy and safe Thanksgiving http://www.sunpac.zoomshare.com:80/...e/trebuchet.css&css=/lib/style/type_album.css

minimum block pressure is 11 psi or so.
without a method to control water pressure at all RPM and the t-stats constanty opening and closing either pressure will go above 30 psi or below 11 psi creating issues
I have asked twice at what RPM this occurs yet you wont say.
forget anything you thought you knew about automobiles.
at low speeds the indication of a stuicking/non sealing valve is low speed overheat and fine above 1200 RPM or so.
excess water pressure is dumped into the exhaust stream
I have never seen the valve or spring go bad but the corrosion will displace the grommet and cause sticking issues that allow the valve to bleed off to much pressure at idle and not allowing the top of the block to fill with water.

I did state that it was occuring at idle. I don't know how you find so much time to respond to all these posts, but it's a great thing. It is running great now I ran it for 15 minutes, with the muff, and the temperture never went above 132. When I held it at about 1200 rpm, the temperature dropped to about 115. More water flow I'm sure. I wll invite you for a Tuna dinner in June, when I'm in Nags Head!!!!! Have a great Thanksgiving everyone. Bob