Water temperature and/or water pump

[Curcio]

I have a 4.3 MerCruiser (OW672475) that is having a problem with the audio alarm. A service rep told me the engine was running hot at 180 degrees and that I needed a new water pump. It seems like it has ALWAY run about 180. Does anyone know what the correct temp should be or what else could cause the alarm? I have good 60-80 lb oil pressure and my lower unit reservoir is full.

 

[alldodge]

Howdy

If you have closed cooling you should have a 170 degree thermostat, if you have open cooling then you should have a 160 degree thermostat.
Running at 180 degrees while not over heating is in the area to have a look if you have open cooling system.

What alarm are you hearing, a solid alarm or beeps?

 

[Curcio]

The alarm is solid, the same one as when the key is on but the engine hasn't started. It's an open system. Manual says it should run at 160 but is 180 enough to go into alarm. Could it just be a stuck thermostat?

 

[Curcio]

What alarm would it be and where would it be ?

 

[Bt Doctur]

when was the impeller in the drive changed last?
when were the manifolds/risers changed last?

 

[Bt Doctur]

a solid alarm could be the drive res float switch, the no oil pressure switch, or the hi engine heat sensor

 

[Curcio]

It's a 2007 with 200 hours. I have never had the impeller in the drive changed, imdidn't know there was one. I though the engine water pump supplied all of the cooling. Couldn't just be a stuck thermostat huh? Where is the high engine temp sensor?

 

[alldodge]

It's a 2007 with 200 hours. I have never had the impeller in the drive changed, imdidn't know there was one. I though the engine water pump supplied all of the cooling. Couldn't just be a stuck thermostat huh? Where is the high engine temp sensor?

As BT stated you have 3 things which can cause a solid alarm. If the alarm comes on after the motor heats up then its the impeller in most cases.

(1) Engine overheat - your reading 180 degrees which is not to hot but your gauge can be off. It can also be caused by a faulty temp switch mounted on the thermostat housing. The FIX is check the impeller and pump in the outdrive.

If its on all the time even when motor is cold it can also be
(2) Low drive lube - Check the lube bottle level
(3) Low oil pressure - Since your engine is still running its shouldn't be low oil pressure because the fuel pump would shut off

 

[Curcio]

Thanks ALLDODGE. It only comes on when I've been pulling skiers for an hour or going 4000 rpm for maybe 20 minutes. It usually goes off almost immediately when I stop (which I do as soon as it sounds) and after maybe 30 seconds I start up and it runs fine for awhile, longer if I just cruise along without skiers or speeding. I'm leaning toward the impeller which I didn't,t even know was there. Thanks for your help! Tom