what does the overheat alarm sound like

G

greenstreak

New Member
Nov 1, 2008
86
I have a 2000 sundancer 270 with mercruiser 7.4 mpi with bravo III. I was told the overheat alarm would be a solid sound from a sea ray dealer. I had an alarm go off today while on cruise and it was a loud beep. It would beep, maybe 1 or 2 second pause and beep again. I came off cruise and idle for a couple of minutes and the beep went away. Not a solid sound. Any ideals?

Thanks

art
 
Hey White Glove

I came down to idle and it kept beeping and i shut engine off and restarted it and the beep was gone. I idled back to dock which was about 1/2 mile and the beep never came back. So I ned to figure out what the beep was if it wasn't the overheating alarm like I thought.

Thanks

art
 
The IAC is the "Idle Air Controller" I doubt it's that because I don't believe it would cause an alarm but will make the boat tough to idle and sometimes start.
As White glove stated it sounds like your Outdrive reservoir is low. Check the level. It's at the front of the engine and you'll see the "level" line on the opaque bottle. It has a sensor for when fluid is low.

You want to use HIGH-PERFORMANCE GEAR LUBE by Quicksilver or Mercruiser.
 
You bet. You should put your boat's info in your signature so we can all see what you have.
 
FWIW - I had an alarm go off after my first hour cruise to my dock. It happened just prior to entering the harbor and I too was on plane. I did just what you did, shut the motor off, restarted and no alarm. I was able to enter the harbor at no-wake speeds and dock her. Every time after that, it was sporadic but basically when on plane or getting on plane. This did not happen during my sea trial, only after I brought her home so I was puzzled. I checked the oil press, the water temp, and the outdrive oil level too. I had mine scanned by a local guy and the fault said "knock sensor" problem. I contacted mercruiser and they said that would not cause the alarm to go off - THEY WERE WRONG!

I chased this problem on my own for a month and finally had the dealer chase it. The dealer had to replace both knock sensors, just like the computer said..... (they also replaced the wire terminal which connects to the sensor as it was corroded too)

Good luck.

Mark
 
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hey mark--Since you have the same boat and engine as mine I got a question. Is the thermostat in the housing right in front above the fan belt that has hoses attached to it. I watch my temp gauge and it will show around 200 while on cruise and 170 while idling, but I have used an ir gun on my engine and it is not near that temp. I shot the elbows and one side was 110 and other side 140. the housing I am talking about was 120. I am sure my gauge is way off in the dash. What about yours?

Thanks
art
 
Does your boat have carbon monoxide detectors?? I know ours beep in such a pattern. A little off topic but maybe worth a look??
 
greenstreak said:
I watch my temp gauge and it will show around 200 while on cruise and 170 while idling, but I have used an ir gun on my engine and it is not near that temp.
Click to expand...

Art - I had a 99 with the same power set up as yours. It ran 170 deg at idle and while at cruise. When was the last time you inspected / changed the water pump?

When the alarm sounded, what was the gauge temp?
 
hey Jeff--My temp gauge was around 200 but I believe my gauge is way off. I have used ir gun on engine and never found any temps near that degree. Also, I was told by mercruiser service that was not an overheat alarm. They said that alarm would be continous and not a beep. they said it probably was the drive reservoir alarm. When i was idling down the river yesterday I used the ir gun on several areas of the engine. Even though the gauge showed 170, the highest reading on engine was 140. That was the right elbow.

Thanks
art
 
Art - Did you get 140 at the thermostat housing at a close range with your ir sensor?
For the most accurate reading, you'd need to get withing a couple inches from the thermo's housing. I can't remember exactly, but seem to have 170 stuck in my memory for a 7.4
 
greenstreak said:
hey mark--Since you have the same boat and engine as mine I got a question. Is the thermostat in the housing right in front above the fan belt that has hoses attached to it. I watch my temp gauge and it will show around 200 while on cruise and 170 while idling, but I have used an ir gun on my engine and it is not near that temp. I shot the elbows and one side was 110 and other side 140. the housing I am talking about was 120. I am sure my gauge is way off in the dash. What about yours?
Click to expand...
Art - I have not used an IR gun yet, but my gage always reads about 175 deg. It never really changes either running at cruise or at idle. I can say that my thermostat housing always feels hotter to the touch than the elbows. My elbows are not hotter than my hand can stand - but I don't really know what temp that is. When I bought my boat, five years ago, the manifolds and risers were replaced as part of the deal. I cleaned them two years ago and will check them again this spring. I believe these are the most common source for temp fluctuations.

My thoughts are, even if your gage is off, why does it change temp by 30 degrees from plane to idle?
BTW - While I am not 100% positive (95), I believe that the temp switch for the computer is not the same as the one for the gage - so if there is an overheat alarm, I am pretty sure it came from a different switch. The sensor for the computer is a two wire 5 volt unit on the manifold, and the gage sensor is a single wire on the tstat housing.

Hope this helps.

p.s. Were you able to confirm the outdrive oil canister was full?
also - I do use the factory suggested 160 deg thermostat.

Mark
 
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You can also get an alarm from insufficient water flow. It could have been something that got sucked up and restricted the flow and when you came off plane it cleared itself. Not saying that's what happened but it is a possibility.
 
Half Off said:
You can also get an alarm from insufficient water flow. It could have been something that got sucked up and restricted the flow and when you came off plane it cleared itself. Not saying that's what happened but it is a possibility.
Click to expand...
Our boats do not have flow sensors, but if that was the case, it would have still set an overheat alarm from the temp sensor for low flow. (IMHO)

Mark
 
hey Mark--Is the thermostat housing the one right in front of engine above the fan belt? the one with several hoses on it? If this is the one then it is never hot. I have put my hand on it and the housing is just warm even when my temp gauge shows 170. If the thermostat was not opening all the way would that housing get hotter?

Thanks
art
 
greenstreak said:
hey Mark--Is the thermostat housing the one right in front of engine above the fan belt? the one with several hoses on it? If this is the one then it is never hot. I have put my hand on it and the housing is just warm even when my temp gauge shows 170. If the thermostat was not opening all the way would that housing get hotter?
Click to expand...
Yes - The thermostat housing has all the water connections and one sensor (temp gage) on it. It has the thermostat held in place with a plastic spacer and it is secured with two 3/8-16 bolts.
 
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