68' 55HP - Newly Rebuilt Engine Runs Cold

[atengnr]

Newly rebuilt. The shop noticed that the thermostat wasnt opening while running in test tank, tried several thermostats but attributed it to cold water in their test tank.

So, I started the motor with the muffs today, and after idling for about 5+ minutes, there was almost no water coming out of the exhaust. The other outlet holes were releasing water, but block was comfortably warm to the touch.

Is this normal?

Thanks

 

[tashasdaddy]

Re: 68' 55HP - Newly Rebuilt Engine Runs Cold

until the motor gets up to temp you will get little water out the exhaust. as long as you have the droplets and mist out the exhaust relief, you should be good. it takes those motors a good time to warm up idleing. you know not to rev the motor above 1,500 rpms on muffs, or in a barrel. there is no load on the the motor, and can cause a run away motor, that can be shut down, other than choke it , or remove fuel source.

 

[Mas]

Re: 68' 55HP - Newly Rebuilt Engine Runs Cold

Take the motor out on the lake near the dock and monitor temp and water flow. If it doesn't heat up, you've got the wrong thermostat.

Try using an infrared thermometer to measure head temps.

MAS

 

[jay_merrill]

Re: 68' 55HP - Newly Rebuilt Engine Runs Cold

Your profile doesn't say where you live, but if you are in an area that is still very cold this may be normal. Especially if the water you are running through the motor is very cold.

The later three cylinder OMCs have a poppet valve system in the thermostat housing that works via water pressure (they open at higher rpm), but yours doesn't. This is in addition to the thermostat, so the poppet valves are a safety system of sorts. Since you don't have them, however,, you need to be careful about this issue. If the thermostat doesn't open in warmer conditions, you will need to find out why.

 

[jay_merrill]

Re: 68' 55HP - Newly Rebuilt Engine Runs Cold

Try using an infrared thermometer to measure head temps.

MAS

I agree that these are nifty tools and I don't have one either. Where can both the OP and I buy one?

 

[atengnr]

Re: 68' 55HP - Newly Rebuilt Engine Runs Cold

Yes, I live in SE michigan, and it was a balmy 50F today. I actually drove to the local lake, hoping to find some open water, it its still frozen solid. So yes, its still cold here, as is the water.

How do I know the thermostat is open? Water thru prop?

The engine by no means seems to be getting hot, as the exhaust mani and block were barely warm to the touch after 5-10 mins running.

Anything that could cause the engine to run cold?

 

[atengnr]

Re: 68' 55HP - Newly Rebuilt Engine Runs Cold

Take the motor out on the lake near the dock and monitor temp and water flow. If it doesn't heat up, you've got the wrong thermostat.

Try using an infrared thermometer to measure head temps.

MAS

How do I monitor water flow? I have no tell-tale....

 

[jay_merrill]

Re: 68' 55HP - Newly Rebuilt Engine Runs Cold

Fuel mixture affects engine temperature, but it is more an issue of running too hot when the mixture is too lean. Besides, if your engine were running excessively rich, you would see it in the form of sooty exhaust and fouled plugs.

 

[tashasdaddy]

Re: 68' 55HP - Newly Rebuilt Engine Runs Cold

you can tell if the impeller is work from droplets and mist out the exhaust relief ports on the back of the leg. that is your tale tell. this means the impeller is pumping. not that the tstat is opening and cooling the motor. this is something that is really hard to diagnois on muffs or in a barrel.