overheat buzzer stays on

[SNOTTY]

I have 02 Merc 50hp 2stroke that the overheat buzzer comes on as soon as I turn the key on. The problem started when it actually did overheat a little (the flushette fell off and I didn't know it). It cooled down and still runs fine, but the buzzer still buzzes. I unplugged what I think is the sending unit in the cylinder head and it made no difference. I need some advice please.

 

[aussieflash]

Re: overheat buzzer stays on

You probably cooked the impeller,they dont like spinning without water.Are you still getting tell tale water?May also have faulty sensor which can be tested with multimeter.

 

[SNOTTY]

Re: overheat buzzer stays on

It did not hurt the engine. It does not overheat now. The telltale pees water very good and the engine runs fine. I unplugged the sensor and it still buzzes as soon as the key is turned on, even when the engine is dead cold.

 

[carholme]

Re: overheat buzzer stays on

Do you know for sure if it is the overheat or the oil level? Disconnect the oil level switch wires at the base of the oil tank and try the key again. You can put your meter between the two leads you remove and there should be no continuity. If there is continuity, the switch is at fault.

You can see the two leads going to the switch, item 13 here:

http://www.crowleymarine.com/mercury-outboard/parts/3373_110.cfm

What is your engine s/n and I'll send you the online version of the service manual.

Gerry

 

[SNOTTY]

Re: overheat buzzer stays on

Thanks Gerry, I will get you the s/n # for you, but I can't post it till tomorow a. m. I would really like to have that service manual. I think the low oil level beeber is a beeep-beep-beep type noise and the overheat beep is a constant beep noise. I will unplug the oil level sensor to be sure though. Thanks, Scott

 

[carholme]

Re: overheat buzzer stays on

Scott;

If you are sure it is a 2002, here is the parts listing for your engine:

http://www.crowleymarine.com/mercury-outboard/3373.cfm

Service Manual P/N: 90-852572R02

http://1manual.com/Mercury manuals/Service Manual PDFs/TwoStroke/852572r1/cover.pdf

You must have Adobe Acrobat reader installed to use this manual. If you scroll down to the lower part of the opening page, you will see the various engine components in red. Click on the one you want and when the first page opens, click on the "Save As" icon at the top LH corner of the page and you can save it to your computer.

Gerry

 

[SNOTTY]

Re: overheat buzzer stays on

Here is the s/n 0t499238. Last night I discovered that if I disconnected either wire going to the low oil sensor the buzzer turned off. I suppose that means I need a new low oil sensor,right? Thanks, Scott

 

[carholme]

Re: overheat buzzer stays on

Scott;

As I said previously, verify by putting a meter across the two leads of the switch.

Your s/n is a model:

1050412ZD MERCURY 2002 50

The previous parts list and service manual I sent you are correct.

Gerry

 

[SNOTTY]

Re: overheat buzzer stays on

The problem was in the oil resivour. Thats fixed. This eng has been sitting for about a year so I had to go through the carbs and now it starts and runs good, but it will only run long enough to empty the cabs. I can pump it up and restart it and it will die as soon as the carb bowls get empty. Fuel pump?

 

[carholme]

Re: overheat buzzer stays on

Scott;

To verify the pump, start it again and when it starts to die, pump the bulb and see if you can keep it running. If so, you will have to re-build the fuel pump.

Gerry

 

[CharlieB]

Re: overheat buzzer stays on

You still need to address that water pump.

One, it has been run without water.

Two, it's old.

Running on the hose is not a good test as the hose pressure will 'assist' the pump and falsely indicate good flow.

 

[SNOTTY]

Re: overheat buzzer stays on

I o/h the fuel pump and it runs great. Thanks for your help.