Displayed Engine Hours and Idling

[sailorboy1]

I checked into a 1981 boat the other day and 1 one of the things I asked was the engine hours. The answer I got was that the meter shows 1030 hours, but that the owner doesn't think the hour meter tracks hours when the engine is at idle. (1030 hours is extremely low for a 29 year boat not matter how you look at it)

I can not think of a way this is possible. How would the meter know if the engine (Perkins 4.108) is at idle. Heck my meter records engine hours if the engine is off but the key is on.

Anyone ever heard of an engine hour meter that doesn't record hours at idle?

[Paul Lefebvre]

I think it was just a nice way of saying that the hour meter was broken and they don't know how many hours are on it. My 30 year old boat was showing 990 hours on it when I bought it, the same number as when the previous owner bought it 13 years earlier. My feeling is at that stage, it doesn't matter how many hours are on it, it is still a 30 year old engine.

Paul

[daddle]

Way back when...you may find 'hour' meters coupled with tachometer that read 'red line hours' and runs proportionally slower with slower RPM. Aircraft use these sometimes. Also, some hour meters are switched by oil pressure so may not run as the engine eats itself alive at low RPM.

[rtbates]

Could be real hours.. Example, on average we burn 4-5 gals of diesel a year...No idea of hours, we have no hour meter, but it can't be many.

[AnchorageGuy]

Don, The hour meter typically runs as soon as the key is on, ours does and so did our previous boat. There were times where I forget to turn the ignition key off and the meter just ticked away if the alarms were disconnected when we were working on things. Our new to us 30 year old boat had 1350 original hours on it with a perfectly good and working hour meter. So it is not a stretch to think this could be the correct hours, but there is no way to tell for sure. Any purchase of a boat should include a thorough survey of the engine by a qualified mechanic and not by the boat surveyor. WG

[jrd22]

I never believe the hour meter unless it is backed up by the maintenance log. Our current engine has 4600 hours on it and I was able to go back through the log and verify that it was accurate (oil changes, repairs, etc). If there is no maintenance log on the engine then the owner didn't take maintenance seriously so I would be wary.

[sailorboy1]

Originally Posted by daddle

Way back when...you may find 'hour' meters coupled with tachometer that read 'red line hours' and runs proportionally slower with slower RPM. Aircraft use these sometimes. Also, some hour meters are switched by oil pressure so may not run as the engine eats itself alive at low RPM.

Well there's a possible. Seems kind of compliated for just a run hour meter for a sailboat. Anyone else even heard of such a thing? Is this why on another thread I had on Pekins 4.108 engines it seemed a lot of boats with this engine; the hour meter had stoped working?

[Blue Stocking]

Don't some of the guages count hours in the form of units of time at 1000rpm.
e.g. 1hr @ 1000rpm would show as 1hr
1hr $ 3500rpm would show as 3 1/2hrs.
I have seen x 1000 marked on the face -- not talking about tachometers.

[Solitude]

Originally Posted by Blue Stocking

Don't some of the guages count hours in the form of units of time at 1000rpm.
e.g. 1hr @ 1000rpm would show as 1hr
1hr $ 3500rpm would show as 3 1/2hrs.
I have seen x 1000 marked on the face -- not talking about tachometers.

I'm not saying they do or dont do this. Its interesting if it did as it is usualy much better to run the engine at the higher rated RPM than have it chug away and glaze the cylinder at idle.

It would be hard to know if the engine had 3000 good hours on it or 3000 bad hours. The differnce being 3000 idle hours or 1000 rated RPM hours.

[amarinesurveyor]

Originally Posted by Blue Stocking

I have seen x 1000 marked on the face -- not talking about tachometers.

You see x 1,000 because the markings on the gauge are 1, 2, 3, 4, etc; 1 being 1,000 rpm, 2 being 2,000 rpm and so on.
I would guess that the meter is not working, in the case of 1000 hours showing in 29 years.
On mechanical tachometers that are driven by a cable similar to the speedometer cable in your car, the hour meter is also dirven by the same cable, so the faster the engine is running, the faster the engine hours add up. I would guess that at normal cruising rpm the hours on the meter would be about the same as actual run time, but if you are running slower the hours would add up slower that actual run time. This actually is a more accurate way to measure engine use. Mechanical tachometers are not very common, and I would think the tach on this boat is electric as most Perkins tachs are run off the alternator.
Brian

[Solitude]

Originally Posted by amarinesurveyor

You see x 1,000 because the markings on the gauge are 1, 2, 3, 4, etc; 1 being 1,000 rpm, 2 being 2,000 rpm and so on.
I would guess that the meter is not working, in the case of 1000 hours showing in 29 years.
On mechanical tachometers that are driven by a cable similar to the speedometer cable in your car, the hour meter is also dirven by the same cable, so the faster the engine is running, the faster the engine hours add up. I would guess that at normal cruising rpm the hours on the meter would be about the same as actual run time, but if you are running slower the hours would add up slower that actual run time. This actually is a more accurate way to measure engine use. Mechanical tachometers are not very common, and I would think the tach on this boat is electric as most Perkins tachs are run off the alternator.
Brian

Wouldn't this mean you could be seeing greater engine wear because it was run at idle? It kind of inverts the idea of low hours indicatiing a good engine. (I know you can't just go on hours = condition, anyway but that way of counting makes it worse)

So back to you could have run the engine at a rated cruising RPM of 3000rpm for less time and better for the engine or run it at idle for a very long time and ruined the engine.