Water pump alert horn

[The twoms]

At the end of last summer I put in a new water pump in my 1981 Johnson 140. The next few times I ran the motor a few seconds after I started the boat the horn would sound and then go off. This year I have had it out twice. Each time the horn would sound for a few secods then go off after I speed up. It does it each time I move fishing spots, etc. The wter pump appears to be working fine. The stream of water is strong and the motor is not hot to the touch at all. Any suggestions?.

 

[jtexas]

Re: Water pump alert horn

first, be aware that the hot horn is not a "water pump alert" - it's operated by a temp switch (one on each head I think) - and doesn't know or care whether the pump is working.

Similarly the pee stream only indicates that the pump is pumping - it says nothing about whether the engine is being cooled adequately. Of course, you know how strong it pees with a new pump, so you'll be able to tell if the pump gets weak.

Possible one of your temp switches is faulty - you can test 'em in a pot of water on the stove, with a multimeter and cooking thermometer. Should close at 183? F - somebody confirm that please.

If they check out ok, inspect your thermostats.

You should also do a compression test, to make sure you haven't damaged the motor by running it hot.

welcome to iboats!

 

[5150abf]

Re: Water pump alert horn

I would change thermostats, sounds like they are opening late or when you hit the throttle the water is going through the presssure relief valves instead of the stats opening.
Tstats are cheap and easy.

 

[The twoms]

Re: Water pump alert horn

I don't think I was very clear in my initial post. I am pretty sure the engine has not got hat. The alert sounds when the engine is cool instead of hot. Are the sensors you are referring to right above the thermostats in each head?

 

[jtexas]

Re: Water pump alert horn

Right, tan wire connected to a temp switch at the top of the cylinder head.

I noticed you said the head was cool to the touch, just wanted to be on the safe side. An alarm that you ignore is no alarm at all, which strikes me as kind of alarming.

One thing I noticed, and hopefully somebody will check me out on this...the motor should run hotter at high speed not cooler. I'm not convinced your cooling system is operating at peak efficiency.

 

[The twoms]

Re: Water pump alert horn

I am sorry, but I am having trouble communicating my problem. But, logically shouldn't the alert horm come on after the engine has run for a while and "heated-up"? Last Sunday I drove an hour to the lake, backed in the trailer, started the motor and the horn went off as soon as I turned the key on. I pulled it up to the dock and turned the engine off while my wife and son parked the truck. They got in the boat, I started it up and the horn sounded again. I pulled away fron the dock and passed the 'No Wake" sign, opened it up and the alarm went off. When we would fish a spot for just a few minutes and start the engine back up it would not sound, but if we stayed in a spot for a long time then it would sound again when we started up. It seems like something is backwards. If I do have a problem with my cooling system, where sohould I start?

 

[jtexas]

Re: Water pump alert horn

ok, not your fault...alarm sounds before the engine's had a chance to warm up and goes silent after, then your alarm is faulty for sure.

Must have been confused when you said "every time I change fishing spots" - I'm more of a "run and gun" kind of fisherman, my motor is generally still warm when I go to crank it.

So I wondered if the fact that the alarm turns off at higher speeds means that it's working, just at lower temperatures than it should; other words, the motor's hotter at idle than at high speed. Stuck thermostats would explain that. Or water pump.

Add to the fact that your symptoms started after a water pump change.....pretty coincidental. Did you do the whole kit or just the impeller? Enough to make ya feel a little uneasy.

Curious about something: does the alarm come back on when you slow down again? For example to idle through the no wake zone at the end of the day?

What I'd do is, test the temp switches and replace if faulty. If not, I'd troubleshoot the wiring harness to find out why the alarm sounds when the engine's cold. Then decide whether to inspect the thermostats.

 

[The twoms]

Re: Water pump alert horn

To answer your questions, I did the whole water pump kit. By no means an I a boat mechaninc, but I have replaced water pumps before and feel like I followed the instructions and it was installed correctly. There was a couple of times last year that the horn sounded at unusual times. That along with I hadn't put in a new pump in a few years is why I replaced it. But the problem does seem worse. At the end of the day Sunday it did not sound when I went through the no wake zone coming in. But I did pull up to the dock by the ramp and let my son out. While he was getting the trailer the boat was ideling and began to sound. I turned it off. When my son got back with the trailer I just threw him a rope and we pulled it onto the trailer without starting it up again.

 

[The twoms]

Re: Water pump alert horn

Also, does a temperature switch have another name?* I was curious about cost but couldn't find it listed as a part under that name.* I do see thermostats and thermostat kits.

 

[jtexas]

Re: Water pump alert horn

check out www.shop.evinrude.com click on "electronic parts catalogue" then drill down to your model #

BRP part number 386686 Temp Switch

if you don't have a manual I highly recommend the OEM service manual -- try kencook.com or marineengine.com

 

[billybones]

Re: Water pump alert horn

Actually mine is desigined to run cooler at WOT then idle. the T stats are closed At idle. just pressure relief valve allows water flow and some back pressure. or you wont have any. At wot the tstat allows more flow. thus more cooling. of course if it gets hot enough the tstat opens. My guess is that the pressure relief valve seal is shot and sticking I would replace it all. t stats and seals.

 

[jtexas]

Re: Water pump alert horn

billy I can't say for sure about your motor, but how most of these outboards work is, the thermostat holds water in, letting it heat up until it reaches operating temperature at idle speed (although on the muffs, the unloaded engine might or might not get that hot). I believe it's normally open most of the time when the engine's warm. The relief valves are (obviously) pressure operated, and open at high speeds when the water pressure is higher and need for cooling greater.

2-stroke outboards (esp carbureted) that do a lot of idling and trolling typically experience carbon build-up in the cylinders because they don't get hot enough to burn it off.

In any case, it's probably premature to act on information you get from a faulty alarm. Although, a 'stat & relief valve inspection ain't a bad idea from a preventive maintenance perspective.