Engine Hour Meter

[Greenhand]

We found out this weekend that the engine hour meter on our new to us boat doesn't work. It had the same reading before and after each of our outings. We had been told that the reading was incorrect, but had understood that this was because it had been replaced.

Is there a way to diagnosis the connections to the existing meter so that I don't go out and buy a new one just to find out that I need to start over from scratch?

PS - This is an hour meter near the nav table, not integral to the tachometer.

[bobofthenorth]

Any hour meter I've ever seen just senses power to operate. So disconnect it completely and then jumper it to 12 volts. If it works then your problem is elsewhere.

[River Cruiser]

The proper way to wire a hour meter is thru a oil pressure switch so that it only counts hours while the engine running and not if someone leaves the switch on by mistake. Check the voltage at the meter, if you have voltage and a good ground the meter is at fault, most I've seen will operate on 4 to 50 vDC.

[dsteinfeld]

Is this a mechanical hour meter or does it have an LCD/LED display? Hour meters with electronic displays may have 2, 3, or 4 terminals and (if more than 2 terminals) require a little more diagnosis.

[model 10]

I have found the oil pressure switch that turns on the hour meter is usually the problem. The little tiny hole in the transducer gets clogged up. A spray bomb of parts cleaner might fix the problem.

[Greenhand]

Originally Posted by dsteinfeld

Is this a mechanical hour meter or does it have an LCD/LED display? Hour meters with electronic displays may have 2, 3, or 4 terminals and (if more than 2 terminals) require a little more diagnosis.

The current one is mechanical and if I had to replace it, I would stick with mechanical.

I can't seem to find information that would allow me to identify the oil pressure switch, if there were one.

[Stu Jackson]

What engine?

[dsteinfeld]

Originally Posted by Greenhand

The current one is mechanical and if I had to replace it, I would stick with mechanical.

I can't seem to find information that would allow me to identify the oil pressure switch, if there were one.

Then the simplest diagnosis is what River Cruiser suggested--measure the voltage across the hour meter with the engine running. If you measure 12v (or whatever your system voltage is) then the hour meter is bad, otherwise the output from the engine (oil pressure switch, etc.) is at fault.

[Greenhand]

Originally Posted by Stu Jackson

What engine?

Yanmar 3HM35F on a 1987 Pearson 39-2. We were told that the engine has 6000 hours, even though the meter reads just under 4k.

We don't have a working fuel gauge, either, so it would be really nice to have an accurate count of engine hours.

[Stu Jackson]

Originally Posted by River Cruiser

The proper way to wire a hour meter is thru a oil pressure switch so that it only counts hours while the engine running and not if someone leaves the switch on by mistake. Check the voltage at the meter, if you have voltage and a good ground the meter is at fault, most I've seen will operate on 4 to 50 vDC.

This is a "Proper" way to do it. In reality, most, if not all boats are simply wired with the hour meter connected to the ignition switch. Sure, it'll show a tad more hours than if it were connected to the oil pressure switch, but over the course of the life of the boat or engine, it simply won't matter. Sure, the time you spend bleeding will count, but what's that, a half a minute twice a year or so when you change filters? That's for electric hour meters found in most boats using a combined tach/hour meter connected to an alternator for the tach.

If you have a mechanical one, it doesn't matter.

Otherwise, good advice to check how the meter works.

Someone with a Yanmar 3xxx can chime in with details specific to your engine.

Your boat, your choice.

Good luck.

[Adventurebound]

Originally Posted by Greenhand

We found out this weekend that the engine hour meter on our new to us boat doesn't work. It had the same reading before and after each of our outings. We had been told that the reading was incorrect, but had understood that this was because it had been replaced.

Is there a way to diagnosis the connections to the existing meter so that I don't go out and buy a new one just to find out that I need to start over from scratch?

PS - This is an hour meter near the nav table, not integral to the tachometer.

Maybe you're buzzing around faster than the speed of light. Time slows down the faster you go.

[River Cruiser]

Stu had a friend that had exactly what you described. While working on something he left one of the switches on and went home. In a couple of weeks or so when he came back the meter racked up about 400 hours while the engine just sat there.

[Stu Jackson]

Originally Posted by River Cruiser

Stu had a friend that had exactly what you described. While working on something he left one of the switches on and went home. In a couple of weeks or so when he came back the meter racked up about 400 hours while the engine just sat there.

Yes, I understand that can happen. On our boat, the main battery switch isalways OFF when we leave. That can't happen. Besides, my ignition key is always taken out when the engine is off.

How'd he do that?!?

Oh, I see.

It's as much a management issue as it is an electrical one, but I DO understand that sh*t can happen.

[model 10]

Hey, this is connected to the "Cool Plane" thread. As a poor corrupt aircraft mechanic I knew how to pull the hour meter fuse and get a little free flight time if my rental joy ride went a little longer than planned.

[Emmalina]

I use a tinytach .. Little digital thing that has a flow sensor you put on an injector line. It gives you exact RPM and only counts hours when the fuel is flowing. Can,t remember the price but not expensive. My old tacho just fills up a hole :-)