Another beep question

[workhorse]

I am completely new to boating - I bought a 1996 Nitro from a coworker. The boat has a 150 Merc 6 cy. This boat has been sitting since 2002 in a garage. I took the boat to have it checked out; new water pump impeller, carb kit, and spark plugs, ($710 worth). Service tech told me that the alarm will not stop sounding, bla, bla, bla. I searched your forum, there seem to be many posts concerning this issue, but there have been a variety of answers.

Problem - as soon as the key is turned on the alarm beebs a constant beeeep and never stops. The engine starts great, runs great etc... beep never stops. There is oil in both tanks and I think the oil supply tank is working, (smoked allot). The mechanic recommended that I mix oil with my gas in the tank to 50:1, so I did. Couldn't be overheating - it beeps right off the bat. Does anyone have the Oil Injection Trouble Shooting Chart for this engine? This was referenced for diagnosing a "constant beep" on a diagram that I read earlier.

 

[jarand82]

Re: Another beep question

A steady beeeeep is normally the over heat alarm. If you have a good tell tale flow then your sending unit is probably bad.

 

[workhorse]

Re: Another beep question

I do have a fairly good tell tale; service guy replaced my water pump impeller, but my pressure reading is real low - might be the sending unit. Any help on where the sending unit is located? I know my way around a car, but don't know @#$% about a boat.

 

[j_martin]

Re: Another beep question

I do have a fairly good tell tale; service guy replaced my water pump impeller, but my pressure reading is real low - might be the sending unit. Any help on where the sending unit is located? I know my way around a car, but don't know @#$% about a boat.

The oil alert and the overheat sensor (a klixon switch mounted on one head) are wired together at a terminal strip high on the starboard side of the engine, near or just over the switchbox mounting plate. Either circuit pulling that wire to ground will sound the alarm. Anything else pulling it to ground, like insulation missing 'cause a mouse ate it will sound the alarm.

Start by taking the 3 wires off that screw and isolating the alarm signal to the oil alert, the temp sender, or the wiring itself. It ain't rocket science. It certaintly ain't as complicated as a modern car.
If your "service guy" was baffled by this, fire him.

The water pressure gauge is a bourdon tube gauge that gets water directly from a fitting on the top of the block. If there's a little water in the gauge and it freezes, it'll overrun the rack in the gear set inside the gauge and forever read low after that. Check the gauge.

If the gauge is at or above zero with the engine off, and it reads real low, the water pump job isn't done right. It may have needed a housing, or a base plate, or a base plate gasket. These items are commonly missed by "service guys".

That engine only runs about 5 lbs of water pressure at idle. 12 - 20 at full tilt, and it varies as you go through the rpm range as the poppit and thermostats respond.

Get a service manual, do a little reading, and you'll soon know @#$% about a boat.

hope it helps
John

 

[workhorse]

Re: Another beep question

John,

Thanks for your help! I found the terminal strip on the starboard side of the engine. The top mounting post holds (3) beige wires with blue stripes. I removed one of the wires, (the top one that leads to the port side of the engine and to a box marked 41470A23, numbers 1066 below), and the alarm no longer sounds. I'm not sure what this means, whether; (a) I disconnected the module that sends the message of "overheating" or (b) I disconnected the wire that may be bad, or (c) the "box" or module 41470A23 / 1066 is bad.

 

[j_martin]

Re: Another beep question

That's the oil alert module. It's bad.

hope it helps
John

 

[marty53]

Re: Another beep question

J_martin is right. I'm sorry you had to pay $710 for very little in parts parts (<$100) and no diagnosis on this relatively simple problem! was this service guy an actual merc. tech? if so... WOW

 

[workhorse]

Re: Another beep question

John/Marty,

Thanks again - I have purchased a repair manual so that I can help myself more in the future. Meanwhile, I've done what any self respecting mechanic would do - I disconnected the alarm! I will replace the oil alert module as you have suggested.

Thanks again,

Blake