Zagato
Well-Known Member
Just interested, does it work from the gearbox, seems pretty accurate...
How Does an Engine Hours Meter Work?
- Thread starter Zagato
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nimbusgb
Well-Known Member
The engine hours meter itself is just a counter. A variety of wiring methods are used. Mine takes its ground from a changeover contact on an oil pressure switch on the main engine and the positive supply from the instrumentation supply. Engine on and oil pressure positive and it quietly counts time. Ignition on but no oil pressure and the clock stops.
They are basically a stopwatch with a control circuit.
They are basically a stopwatch with a control circuit.
macd
Well-Known Member
Most are electrical, simply wired with the ignition (as is mine). They can also be connected via an oil pressure switch or some other sensor that will allow the hour meter to count only when the engine is actually running.
...as nimbusgb has already writ.
...as nimbusgb has already writ.
PCUK
Well-Known Member
You can also get a vibrating type that works like a self winding watch. It is bolted to the engine and only runs when the engine is running and causing it to vibrate.
Tony Cross
Well-Known Member
Mine is just a clock, on when the ignition is on and off when the ignition is....err...off.
Lakesailor
Well-Known Member
So it doesn't count the (last) 10 minutes that you ran with no oil pressure?
nimbusgb
Well-Known Member
macd
Well-Known Member
nope that's recorded in the volume and number of the knocks from the big ends.
...which in turn is recorded to two decimal places in your bank account.
Boathook
Well-Known Member
Mine works from the ignition switch.
nigelmercier
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I replaced the one in my rev counter, details on request. It turns on with the instruments, but only counts when the ignition is on.
scottie
Well-Known Member
There are also vibration meter that are activated by engine vibration and also mechanical units either stand alone or built in to mechanical tachometers that work directly of a gear in the engine but these are suited to constant speed units such as gen sets as they count revolutions and devide by revs per hour
Both of these were popular on older engines some of which had minimal electrics.
Both of these were popular on older engines some of which had minimal electrics.
Daydream believer
Well-Known Member
Following advice from this forum i purchased one from RS
It is wired into the alternator so when not revolving no charge so no hours
Fitting it was a useful exercise as the studs on the alternator were rusty. normally i would have left well alone but i deliberately tried to undo them on the basis that if ever i broke any wires to the alternator i would not be able to renew them. Sure enough 2 broke
I took alternator for refurb & it turned out one bearing & regulator was shot
All in all a useful exercise although expensive
It is wired into the alternator so when not revolving no charge so no hours
Fitting it was a useful exercise as the studs on the alternator were rusty. normally i would have left well alone but i deliberately tried to undo them on the basis that if ever i broke any wires to the alternator i would not be able to renew them. Sure enough 2 broke
I took alternator for refurb & it turned out one bearing & regulator was shot
All in all a useful exercise although expensive
Anders_P42
Well-Known Member
I'm surprised engine rpm isn't factored in to how quickly the hour meter spins. You could have two identical boats, one owner flush with cash cruises at WOT 3500rpm, the other can only afford max 2000rpm. One set of engines have done a lot more work than the other?
Anders
Anders
nigelmercier
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Because then it wouldn't be an hour meter, it would be accumulated revs. But I take the point.
This is why I never do exercise, I figure a human heart is good for a given number of beats.
I'm wondering if the OP wanted to know how they actually work, as opposed to how they are connected. The digital ones are like a digital watch, but there is a switch inside that only allows them to increment when the enable input is active.
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DaveS
Well-Known Member
Well, an engine hours counter does what it says on the tin - counts the hours an engine has run since the counter was installed.
I think you're trying to design a gauge which would put a numerical value on "how worn is the oil?" - or maybe the engine?. This would need to account for more than just revs, since things like time spent idling, in/out of gear and so on all have an effect. (Without complete agreement on any of these factors - see several threads on this forum.) Even if it was possible to gain agreement on weighting factors (maybe different for different engines) I struggle to see why anyone would want one. It might be possible to get a more accurate measure of when to change the oil, but if this was over the manufacturer's (deliberately conservative) hours figure are you going to risk it?
LadyInBed
Well-Known Member
I changed to a Lascar 12v hr meter
http://uk.rs-online.com/web/p/hour-meters/3656274/
It gives me dual function: Engine hours total and a resettable timer, which I reset to zero when I fill up with fuel, so I can easily work out fuel consumption.
http://uk.rs-online.com/web/p/hour-meters/3656274/
It gives me dual function: Engine hours total and a resettable timer, which I reset to zero when I fill up with fuel, so I can easily work out fuel consumption.
William_H
Well-Known Member
More waffle from olewill. Interesting as you say it depends what you wan to know. Now a in gas turbine engine especially a big jet, the life condition is more dependant on number of starts (cycles) so that is often the recorded measure of wear. Quite likely with your diesel boat engine number of starts from cold would be idicative of wear also. good luck olewill
Anders_P42
Well-Known Member
DaveS, I hear what you are saying, there are many many factors if you're trying to keep track of engine wear. I don't see a flaw having an rpm divider on the hours meter. If the manufacturer rates an engine at 90% full revs @ 3500rpm (3150rpm), why not call one hour on the clock one hour at 3150rpm? If the engine operates at half 3150rpm for an hour the clock counts half an hour.
