Overheat alarm

[Richard D]

Is there an oil alarm as well as an overheat alarm on a 1998 60 HP Yahama or can the overheat alarm go bad? I have replaced impeller, theromastat and thermo switch, cleaned water jacket and still the alarm goes off after running for 20 minutes or so. Alarm does not go off if connected to flusher or running for 30 minutes in a barrell? Is there more to cleaning the cooling system than I can get to without a major tear down?
Richard

[99yam40]

Is this a pre mix or oil injected motor?

If it has a oil tank then there should be a oil level alarm

[Richard D]

It is premix so I should only have overheat alarm correct?

[99yam40]

That should be correct.
Maybe pump is sucking air or exhaust if there is a leak of some sort in the system.
May try replacing housing along with the cup and plate.

[Richard D]

Thanks 99, I plan to drop the lower unit and inspect all parts for defects. As the motor is 12 years old it's quite likely more parts are worn.
Richard D

[Richard D]

Still runs hot

Cleaned water jacket, installed new impeller & water seal but 60 Hp yahma still runs hot. Pump seems to be pumping sufficient water but now, when theromast opens, get very little if any hot water released through ports. Also tried with thermo out but no water released hot or cold. Blockage somewhere in motor?? Anyone have any suggestions??
Richard

[Ray Ritchotte]

Have you found the problem yet ?

[Richard D]

No, not yet. Looks like I need to find a repair manual to see just how the water is supposed to circulate - have a leak or blockage somewhere in system.
Richard

[D_MON]

I have a similar problem with my 1990 CV40ELD. Overheat alarm sounds after running on plane for a few minutes, stops on idling engine. Tell-tale water stream is strong and cold, cylinder head is warm to touch, I can readily keep my hand on it.

Replaced thermostat, temperature sensor and rebuilt water pump.

While running yesterday I observed that when the alarm sounded there was very hot water and exhaust leaking under the bottom cowling at the top of the upper casing. This observation would seem to indicate a water and exhaust seal problem in the area of exhaust manifold.

Any help would be appreciated to drive this to root cause!