No engine alarms. Can’t find anything in service manual.

[Sparkinator]

I’ve got a joint venture OMC/Volvo penta Ford 5.0 engine and SX drive. 1995. Aphue. My engine has overheated twice since I’ve owned the boat. Both times were when the impeller failed when putting the boat back in service after winter.
Anyway, on both occasions, I never got a high temp alarm. And I’m not sure how that system works. After reading up, I believe I should get a low oil pressure alarm immediately when I turn the key on as well. I’ve never gotten either one of these. The service manual isn’t clear on how these work either.
just looking for insight on how to repair this problem and parts needed. I’ve never seen a horn or buzzer listed on any parts schematic either.
Thanks for any help.

 

[Bt Doctur]

a horn or buzzer will be under the helm. They work on a "ground" . When the temp or oil ground ,the alarm sounds. Switches usually located on the therm housing or intake manifold, oil near the oil pressure sender for the gauge

 

[Sparkinator]

Thanks. I’ll look for the horn under the dash in a bit. It should have 2 wires? + & - ? I’ll start with the horn and go back from there. Looks like the alarm isn’t working for either condition so hopefully that’s the problem. Thanks

 

[kenny nunez]

It will also help if you added a water pressure gauge which will show a low reading before the engine overheats.

 

[Sparkinator]

I can’t find the buzzer or the high water temp “breaker” on the 5.0 carbed intake. Can’t find the buzzer or horn either. I believe that must not have been an option on my model. I’ve found the water temp sending unit under the coil, but that’s it. I’ll have to look if the is a plug in the intake I could use to add one.

 

[Sparkinator]

I found another plug in the intake manifold. Looks like it’s in the water jacket (pretty sure). It’s right behind the distributor. I just can’t find a sensor for that plug.
again, I’ve got the sending unit for the temp gauge. That’s working fine. I’m looking for the sensor that triggers the alarm for high temp. This is on a Ford 5.0 (302). I can hook up a warning horn pretty easily. TIA.

 

[Horigan]

I have the same engine and the audible alarm is an option. It has the SLOW system that puts the boat into limp mode (limits to 2700 rpm) if the water temp gets too high or the oil pressure gets too low. There are dedicated switches, not sensors, for these functions. I believe they close to ground when the switch threshold is reached. I don't know where the switches are, but they have black/tan wires that are spliced together that go to pin 24 of the ECA.

 

[Sparkinator]

Thanks. You’ve got the fuel injected 5.0 correct? Mine is carbed 5.0. I’m finding out I don’t have any of those protections offered as options. The high water temp alarm or low oil pressure alarms. As far as limp mode, carbed doesn’t have the ECU so I don’t have that either.
I’m either gonna get access to a water port to get a high temp shutdown switch or mount a water temp gauge as big as a sundial on top of the dash. This engine has overheated twice and burned up all the exhaust boots and the trim system wiring the last time. It actually melted the plug for the trim wiring. It got hot! I’m shocked it hadn’t blown a head gasket or warped the heads. This is a tough little engine.
Both times, my kids were out in it and just not paying attention. I just want to get a safety system in place when it overheats again. I’m trying to avoid damaging the heads.

 

[bruceb58]

The buzzer or horn isn't always installed. My 98 Volvo didn't have one. It's up to the boat manufacturer who installed the engine/drive

 

[Sparkinator]

Bruce. And I can’t even find a high temp sensor on any part schematic for a carbed engine. I only see them on the fuel injected models.
I’ve found a Sierra high temp sensor for about $20 I’m going to install if it will fit. I found a plugged port directly behind the distributor (Ford is in the front) that I would like to use. I’m having a little trouble getting that plug out though after being in there 26 years. Gonna have to put some heat to it I believe.
Do you think a “T” would work if I cam off the water temp sensor port and then tied both the temp sending unit and high temp sensor both off the same port? I know using those probes are immersed in the water flow.

 

[bruceb58]

There isn't even a guarantee that you would detect an overheat if there was no water flow. all depends on the heat soak in that area where the sensor is. By the time the sensor got up to temp with no waterflow on it, the other parts of the engine may be way hotter.

 

[Sparkinator]

Yeah Bruce. That routing didn’t seem very efficient or responsive with a water deadhead split to both sensors. They should be immersed in the flow of the cooling water. I’ll pick up a little hand acetylene torch and try to free up that plug in the intake manifold. I should be able install a high temp probe in that port. Then just get a fairly loud buzzer to mount under the dash.

 

[Sparkinator]

I got the plug out of the intake with a little heat and penetrating oil. I found a Sierra hi temp switch online that fit perfectly. 3/8 pipe thread I believe. Now I need to get a loud 12 volt buzzer and wire it up. The switch should close the ground side of the loop if the engine overheats and activate the alarm.
That shiny new part is the hi temp switch. It’s just behind the distributor.

 

[Scott Danforth]

why not be smarter and install a water pressure gauge. you are supposed to be watching the gauges all the time anyway.

with a water pressure gauge you will know of a problem 3-4 minutes before any over-heat switch goes off.

 

[Sparkinator]

Why the “be smarter” line? I just don’t get why forum members feel the need to talk down to other members. If that wasn’t your intention then just disregard.
It’s more for my kids and others while they are driving the boat. They aren’t as interested in watching the gauges.
As far as being smarter, how many pressure gauges are sold on new ski boats and runabouts? High temp alarms are on almost all new boats, even outboards. More so than pressure gauges. People, especially young people, don’t watch gauges in vehicles nearly like they should. I think it’s a generational thing. And women on the whole aren’t mechanical by nature and almost all don’t watch them. You’re average recreational boater just isn’t watching gauges either. That’s why manufacturers put high temp alarms on them. Heck, most runabouts have bolsters built into the seat so the gauges are even further out of their view.
If my kids watched gauges, the water temp gauge was telling them there was a problem as it slowly climbed off the top of the scale. Both times! If they won’t watch a temp gauge, they won’t watch a water pressure gauge either. The temp gauge was working perfectly the other 2 times they overheated the engine and all the exhaust boots were melted and the seals and gaskets in the carb were melted.
If I found another port in the manifold for a water pressure gauge I would have installed one as well, but there isn’t one.
And I could ***** and threaten all of my kids and others who drive our boat with “being smarter” and not such an idiot for whatever reason, but then they wouldn’t come back to my house on the lake and I wouldn’t have a need for all these boats, that I bought, so they would come visit, and bring their kids, and have a good time on the lake.

 

[Scott Danforth]

Because by the time a temp switch and alarm goes off, its already too late

 

[bruceb58]

Actually, both of my boats(outboard and I/O) came with pressure gauges. It's a good thing to have. My outboard doesn't even have a temp gauge.

 

[Sparkinator]

If I ever redesign my instrument layout in the dash it will have all the important gauges at the top and installed so all the indicators point straight up when they are running normally. and oversized gauges. Like a NASCAR or drag car. Manufacturers put speedo almost useless on a boat) and tach (fairly important, depends on application) in the high profile and easily readable positions and oversized them. The important ones (if they have them) are much smaller and below line of sight so you have to look for them. Most have no optimal ranges marked either. It’s pretty sad.

And a buddy saved his engine when the over temp water sensor alarm went off, so they are helpful. My pontoon and bass boat both have outboard mercs and both have the high temp alarms and low 2 stoke oil reservoir sensors that are pretty popular. Neither have any kind of water temp or water flow gauges. It’s a pretty popular setup.

 

[Scott Danforth]

When I redid my dash, 5" 4 in one gauge on left, 3" speedo in center, 5" tach on right, flanking the gauges, oil temp and water pressure in right, depth and hour meter on left

I did add an over temp sender (180F) and oil pressure switch (29psi) to kill the fuel pump and ignition. Both times I ran aground into muck and lost water pressure, i was able to catch it long before an alarm went off

On my last motor, I went about 5 minutes without water and smelled burning exhaust rubber long before I overheated. That is why I added the water pressure gauge

Best gauge for health of a cooling system is water pressure

 

[Sparkinator]

My gauges are a cluster (literally and figuratively) and all feed from a motherboard in the gauge housing behind all the gauges. A winter project not too far off will be new gauges and panel. Gonna remove the entire gauge assembly ( it’s one piece) and design a new cluster. Water and oil info will be up high and prominent and the biggest gauges I can find. A lot of the new cheaper depth finders have gps for speed, so speedo in the dash really isn’t necessary and tube type aren’t known for accuracy. My bass boat speedo isn’t working so I just use the depth finder. That’s If I’m ever curios about the speed.