Temp alarm

[jwieneck]

I was sailing up the bay today when the wind just stopped so I started up the engine. I had been running at pretty low rpms trying to motor sail but finally gave up. So I decided to run the engine full out for a little while my machanic had told me I should do this from time to time. After maybe 5 to 10 minutes running at 2900 rpm which is continues operating rpms for my engine (55 hp yanmar) the temp alarm came on. I shut the engine down and checked all the normal places
sea cock strainer -- ok cleaned it anyway
coolant over flow -- ok between low and high
Good flow coming out of the exhausted

So I waited a few minutes and restarted the engine. The alarm came on then turned off. I motored at 1500 rpms for a while temp was normal, oil pressure normal. Ran it up to 1800 rpms all normal, ran it up to 2400 rpms until I reach our channel to go home all was normal. Any thoughts on what could be the issue?

 

[ALNims]

Loose connection on the temperature alarm circuit?

 

[kloudie1]

Fouling partly restricting the sea water thru-hull outside the boat; broken impeller in pump, fouling on propeller, fouling inside heat exchanger, restricted exhaust elbow. Lotsa other stuff too, but those would be the first wave of checks.

 

[jwieneck]

I will check that thanks

 

[jwieneck]

Fouling partly restricting the sea water thru-hull outside the boat; broken impeller in pump, fouling on propeller, fouling inside heat exchanger, restricted exhaust elbow. Lotsa other stuff too, but those would be the first wave of checks.

These are good I check them. I plan to pull the impeller later today to see if I lost a blade. Thanks

 

[HMT2]

I had a similar experience but with the oil sensor alarm. Ran all the diagnostics, had oil, no leaks etc.. Could find no reason for the alarm to be going off. Switched out the sensor, on the engine it's easy to do. Fixed the problem.

 

[SEMPERAVANTI41]

Does your boat have a temperature gauge? If so, what did it read? As the alarm did not go off when operating at lower rpm, I would guess the alarm is operating OK. You could pull the sensor from the engine and check it's operation with a circuit tester, hot water in a pot on a stove and a kitchen thermometer. After you check the impeller you could also help pin piont the possible source of blockage in your cooling system with a laser thermometer to find the area where the temperature spikes.

 

[jwieneck]

Does your boat have a temperature gauge? If so, what did it read? As the alarm did not go off when operating at lower rpm, I would guess the alarm is operating OK. You could pull the sensor from the engine and check it's operation with a circuit tester, hot water in a pot on a stove and a kitchen thermometer. After you check the impeller you could also help pin piont the possible source of blockage in your cooling system with a laser thermometer to find the area where the temperature spikes.

Yea it dose burin the moment I did not look it was in the normal ranger a few minutes after. I pulled the impeller it looks like new. Ran it at the dock up to 2000 rpm all is normal. I am thing it could be the sensor. I need to read up on where it is and hoe to replace it. Thanks

 

[PGIJon]

If you need an extra hand, let me know. -Jon

 

[Capt jgw]

Could be the sender, but more often the wire to it. Could be loose or corroded connector, or a bare spot grounding out. Especially if it is intermittent.

 

[ben solomon]

I have the exact same problem on my boat. 2000 RPM forever, no issues. 2300 or higher and I run hot. I have researched this extensively and have come to this conclusion: the issue as one poster suggested is restricted cooling water flow. So, it is either the heat exchanger tubes that are clogged/corroded, or the mixing elbow is clogged/corroded. The fix is to look at them, and clean or replace. It appears to be easy enough to do, just takes time. Or, have it professionally done (which may be the way to I have to go for time's sake.). Also, there is a small inlet piece that brings water into the mixing elbow that has a 90 degree angle bend. I have read that a small amount of corrosion in this piece can cause the overheating, as well.

Ben

 

[1mcarlson]

Does anyone know if they make a sending unit that can be hooked right up to a NMEA circuit? I know that my Garmin display has the ability to read engine temp but I cannot find a sending unit that converts the signal. I would think it should be pretty simple and someone has them.

 

[ben solomon]

Some have written about Cruzpro. I have checked them out before. Looks promising. I have no first hand experience, though.

 

[1mcarlson]

Let me look into them. I thought I had at one time but didn't find anything. I will let you know what I find. THANKS!!!

 

[ben solomon]

I remember, now....Maretron makes one and Actisense makes devices to convert analog data into NMEA. Good luck!

Ben.

 

[MitchM]

1) " coolant over flow -- ok between low and high."" yammers are very sensitive to keeping the correct amount of coolant in the overflow tank. keep it full to the high line and see if you still have the problem. on our 2GM20F it would give a temp alarm if the coolant got to 'low.'
2) have you ever cleaned your heat exchanger tubes? restrictions from buildup in those tubes could be your problem. order new gaskets, and clean out the tubes...

 

[CATBOAT WILLY]

Get yourself an infer-red temperature reading device and check the actual heat at the water exhaust port.Then at the block. Sounds like you need you heat exchanger tubes cleaned out.
+ One of the best gadgets I've ever installed was a Borel Raw Water Alarm. Check them out on the web.