posted 07-11-2002 02:28 AM ET (US)        

On occasion the engine alarm sounds. I have misplaced my owner's manual. Does this alarm indicate over heating, inadequate amount of 2-cycle oil in the reservoir, or what? The latest episode occurred when returning to my slip after filling up with fuel. However, the alarm did not activate minutes earlier when I went out for a six-mile spin. Other than clogged water journals, sticking thermostates or a malfunctioning water pump, can anyone think of what the alarm means and the possible cause(s).

posted 07-11-2002 09:33 AM ET (US)            

You didn't state what brand of motor you have so I'm not sure if the information below applies. For Mercury motors with horsepower of 135, 150, 175, 200 (1995 Manual) the following is stated:

The Warning Horn Sounds Continuously

Problem - Engine overheat. The warning sysstem is activated when the engine temperatue is too hot.

The Warning Horn Sounds Intermittent Short Beeps

Possible Problems: 1. Low oil level in the oil injection system. 2. the oil injection pump may have failed or 3. The water sepaarating fuel filter (electronic fuel injection models) is full of water.

posted 07-11-2002 09:36 AM ET (US)            

I'm not familiar with the Yamaha system but a 1998 Yamaha is very similar to an OMC motor of that same vintage. You might check out this thread: http://continuouswave.com/ubb/Forum4/HTML/000894.html

I do not think this sounds like a fuel restriction problem because it happened at slow speeds. If there was a fuel restriction it would (and on my boat, always did) happen at near WOT when the motor was demanding a lot of fuel. Idling back to your slip the motor would not be requiring very much fuel at all and would live happily with quite a substantial fuel restriction.

If the engine is overheating then the temperature gauge will be giving some indication of this. What was it doing?

posted 07-11-2002 10:50 AM ET (US)            

I am taking this opportunity to commend you for your contributions to this forum. Your answers are always well thought out and a great deal of the time you reference another thread that pertains to the problem. When I read your answer to Mario, I thought "how does he know that Mario has a Yamaha engine". I then looked a Mario's profile and saw the connection to Cetacea, p. 48, where Mario stated that he had a 200 HP Yamaha on his boat. However, I still haven't determined how you knew the motor was a 1998 Model.

Once again thanks for having you aboard.

posted 07-12-2002 09:23 AM ET (US)            

If a vacuum forms in the VRO tank the intermittent alarm may sound. I have had this happen on occasion. Simple fix-unscrew VRO cap and then tighten. You'll know there is/was a vacuum when you unscrew the cap and hear a small rush of air.

posted 07-16-2002 02:56 AM ET (US)            

I apologize for not responding sooner. First I want to thank you for all of your assistance. Second, technical writing is one of my job descriptions, so I'm a little embarrassed that I did not provide all the facts and specifics on my engine and the associated symptoms. Yes Tom, my engine is a 1988 Yamaha. It has a 200 HP rating. Therefore, your investigation assumptions are correct. Some important conditions and facts that I did not mention include:

-- Water discharge stream is not as strong as I remember when I did not experience the alarm problem. The stream does appear to be stronger when cruising at speed.
-- The engine has 960 hours of operation.
-- I have not been judicious in flushing the engine after use, which has always been in salt water.
-- The oil reservoir at the engine is full when the alarm sounds. At one time I did experience oil supply problems, but this condition had been repaired.
-- The alarm (buzzer) sounds continuously. No intermittent alarm has ever sounded.
-- The engine does not exhibit any loss of power, or make unusual sounds when running at slow or higher RPMs. I recollect when I did have my owner's manual, it stated that the Yamaha engine automatically reduces its revolutions when overheating occurs. A drop in revs has not occurred. However, again the alarm has only sounded at low revolutions 600- 1100 RPMs.
-- When the alarm sounds, a light mist/steam is discharged from what appears to be the upper exhaust ports. However, I'm not sure if this not normal? If it is not normal, then the engine is definitely overheating.

David R., primer bulb is approximately 3 years old. However, I will mention this possibility to the mechanic that will be looking at my engine. If 3 years is too long, then it's an easy and inexpensive repair to make. As far as problems with the ignition switch, this source cannot be ruled out. My boat has been in the water (salt) for almost 13 years. This type of exposure has resulted in the malfunction of several other electrical switches. The ignition switch is original equipment.

David, Since the oil injection problem was fixed last year, I do not believe that this is the cause of the problem. However, I will also discuss this possibility with my mechanic. I did not consider the water separator fuel filter possibility, and the filter is well overdue for replacement. Before I take the boat to my mechanic, I will replace the filter and see if the problem is corrected.

Tom, I checked out the link, thanks. I do not have an independent temperature gage. There are 3 idiot lights on the tachometer. I will need to look more closely at this gage to see any of the 3 light illuminate when the alarm sounds.

aube, I'm not familiar with the VRO tank. Is this the small oil reservoir on the engine, or the large detached reservoir? Unless I'm way off on my assumption, I will unscrew the caps of both reservoirs.

Again, I want to thank all of you for your impute. I will post my mechanics findings after the problem(s) is isolated.

posted 07-16-2002 10:12 AM ET (US)            

Well, I think you have answered your own question. The motor is overheating. To repair, tart with the simple things first.

Replace the water pump impeller, key and seals. Replace the water pump housing and plate too if it looks like it needs it. If this doesn't solve the problem then you probably have partially blocked internal cooling passages and you will have to dig into it to clean it up.

You do not have a VRO tank because VRO is the term for OMC's variable ratio oiling system. At any rate, what aubv refers to the VRO tank is the large remote reservoir. This reservoir is not your problem nor is the primer bulb.

posted 07-18-2002 07:50 PM ET (US)            

I hope it is just the impeller and not the water jackets! It will be a couple of weeks before my mechanic can get to it. Like a good mechanic, he is reserving his comment until he checks out the engine at his shop. I'll keep all of you posted.

Thanks,

posted 07-19-2002 11:22 PM ET (US)            

I have not taken the boat out much in the last 6 months, so I don't think it is a seaweed problem. However someone lowered my engine into the water a couple of months back, and a large amount of growth accumulated on the lower end unit. Perhaps, this growth was sucked into the water intake. Who knows until we take the engine apart.

csj,

I finally found the engine maintenance and repair manual for my engine. Malfunctioning thermostat(s) was one of the potential problem areas. I would not rule out this cause. However, the tell-tail water stream is definitely not as strong as I remember. So, I'm still betting it's the water pump and/or blocked water passages. Oh, by the way, the manual states that you can purchase "MARKEL" thermo sticks (like a large crayon) that leave heat sensitive markings on the power head. The marking melts at the stick's rated temperature. You mark the head with two crayons, one that melts at the cool end of the engines proper operating range and one that melts at the upper end. If the lower end stick's marking does not melt, the engine is running to cool. If the upper end stick's marking melts, the engine is overheating.

NOTE: THE MANUAL RECOMMENDS REPLACING THE IMPELLER ONCE A YEAR OR WHENEVER THE GEARCASE IS REMOVED FOR SERVICE. I DOUBT MOST OF US DO NOT REPLACE THE IMPELLER THIS OFTEN. THE MANUAL ALSO STATES THAT AT LOW SPEEDS THE IMPELLER OPERATES AS A DISPLACEMENT TYPE, AT HIGH SPEEDS LIKE A CENTRIFUGAL TYPE. PERHAPS THERE IS A CORRELATION AS TO WHY AT HIGH SPEEDS THE OVERHEAT ALARM DOES NOT SOUND, BUT AT LOW SPEEDS IT DOES.

THE MANUAL ALSO STATES THAT THE LACK OF LUBRICATION, SPARK PLUGS OF THE WRONG HEAT RANGE, INCORRECT IGNITION TIMING, EXCESSIVELY LEAN FUEL MIXTURE AND TOO LARGE A PROPELLER CAN RESULT IN ENGINE OVERHEATING.

THAT'S ALL I HAVE TIME FOR NOW. I'LL KEEP EVERYONE POSTED WHEN THEY WORK ON THE ENGINE IS COMPLETE.

posted 07-22-2002 11:36 AM ET (US)            

You have provided yet more critical clues to your situation! I now strongly suspect clogging in the cooling passages of the water pump from marine growth.

While it is good to replace the thermostat, I suspect this is not your problem. It the thermostat needs replacement it is because it is either stuck open or stuck shut. If it stuck open, the motor will run cold or at least take a long time to warm up. If it stuck shut, or partially shut, then the motor may run fine at slow speeds but over heat while running faster. This is not your situation.

If there is growth in the pump housing itself it could damage the blades or vanes of the impeller. As you have noted, at slow speeds the pump works as a displacement type pump and relied on the vanes making good contact with the sides of the pump housing. At faster speed the vanes are forced away from the sides of the housing by water pressure and good contact is not necessary for the pump to move water.

This same situation could also be caused by an impeller that is just old and has a set to the vanes. This is why impellers should be replaced periodically whether the motor is used or not.

posted 07-23-2002 01:48 AM ET (US)            

Captain Tidy and Moracco have offered to loan me their trailers, so I'm planning to take Victoria out of the water for repairs this comming weekend. I'll keep everyone posted.

posted 07-23-2002 12:48 PM ET (US)         

Is a temp. gauge easy to install? I have a OMC 150 Ocean Pro and Id like to add one. Is this something a novice could do?

posted 07-24-2002 02:38 AM ET (US)            

It is very easy to install. Your motor may be new enough that there is a more integrated provision made for the installation but if not then you just bolt the sensor to one of the heads of the motor and run the tan wire from the sender to the gauge.

The gauge needs a positive and negative lead for power and you may want to have the dial illuminated by an optional light with a blue lead wired with your nav light switch.

Read your owner's manual or ask your dealer about your particular motor.

posted 09-01-2002 02:54 AM ET (US)         

We are on to temp gauges!

On my current motor pair one of them had a head gasket problem that popped up in the San Juan's (now fixed). This problem caused 1/2 of my V6 to overheat. I found the problem by disconnecting one and then the other over-temp sender.

My "big picture" issue is that a temp gauge could give you a false sense of security if it's on the wrong half of your block as you look down at a gauge in the green.

Of course you 3cyl guys can ingore all of this.

Maybe two temp probes and a left right bank switch for each motor?