Engine hour meter overestimates

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When I replaced my hour meter a few months ago, I wired it to a 12v battery until it had clocked the previous HM hours, which was about 350 hours. That way it began its duty with the correct number of hours.

Cheers, Bill

I'm doing the same thing....Had it all caught up at 1485 hours then never got in installed. Need to add a few now (to 1562) and get it wired!

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When I was doing new Defever deliveries in 1983/84 time frame, dealer would disconnect meter at beginning of the trip. The boats were off loaded in Baltimore, commissioned in Annapolis and delivered to boat shows up and down the east coast. I asked the dealer who would think that their new boat would have no hours on it? I was also told to shut up and say they do 11-12kts. One of my eye opening experiences of a 22year old.
 
Why bother running the new meter up.
Replace the failed unit with a new one and LOG the hours.
Worked for two meters for me.
I kept the old meters so if questioned I can show them. If they don't believe me so be it.
The old meters both failed at about 15-1800 hrs. Both Hobbs mechanical.

The new one, a Hobbs Quartz, is running still pushing 3,000 hrs.
If it fails I will do the same as before.
All a meter means to me is when to do service work, either by hours or time, depending upon which is most important as most recreational boats don't clock a lot of hours.

Jim Cave,
I would suggest that you get yourself an independent hour meter if it concerns you. Install it where it can be seen when needed. It does NOT need to be front and centre. Log the hours with some notes about why you stopped trusting the original and that the new one is what you go by and carry on.

In my Mtce. log book is a light cardboard divider right at the front and in big letters when the changes were made. Also entered where the date would fall in the rest of the pages.
 
Thanks Clectric. That's exactly what I was thinking as well.


Jim
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A good place for an hour meter is on your automatic bilge pump.
 
I found out the other day that when I turn the power on at the helm station with the ignition key the hour meter runs even if I don't start the engine. So I have no idea how many hours are on my engine. I bought the boat in May and am keeping a log of the hours that I run the engine. The hour meter now means nothing to me.
 
I found out the other day that when I turn the power on at the helm station with the ignition key the hour meter runs even if I don't start the engine. So I have no idea how many hours are on my engine. I bought the boat in May and am keeping a log of the hours that I run the engine. The hour meter now means nothing to me.

Why would you have the ignition key on if the engine isn't running?

Ted
 
Why would you have the ignition key on if the engine isn't running?

Ted


Why does it matter. The thread is about an engine hour meter overestimating the time that the engine is running. I offered a reason as to why it would happen.
 
jdud, does your boat have oil pressure/overheat alarms that sound when the key is turned on?
 
"I turn the power on at the helm station with the ignition key the hour meter runs even if I don't start the engine."

This is the normal KISS installation.

For better accuracy you could use an oil pressure switch that would only run the clock only with the engine on.

But with the short time the "key" is on before the engine is operated , almost no one bothers with added complexity.
 
I just confirmed that my VDO tachometer is under reading by about 30%. I checked my logs and it's been consistent since I got the boat in March. I also consistently run it at about 70% of full RPM. Could it be that my hour meter is scaled by RPM?

Richard
 
...Could it be that my hour meter is scaled by RPM?

Richard

Most VDO tachs with hour meters for our vintage boats have a DC driven hour meter. An easy way to check is to turn the key on and watch. You should see some movement. Our hour meter is powered by the same 12 VDC that is for the tach illumination.
 
Most VDO tachs with hour meters for our vintage boats have a DC driven hour meter. An easy way to check is to turn the key on and watch. You should see some movement. Our hour meter is powered by the same 12 VDC that is for the tach illumination.

Thanks - I'll try that. If so then I guess my meter is faulty. I wonder how long that's been true - the engine hours could be up to 40% higher than recorded.

Richard
 
Larry's advice worked for me. There is a thread that I started last spring called"Tachometer Adjustment" that covers the process. I set the engine at cruise RPM's with the laser tachometer then matched the tachometer on the Pilothouse helm with the set screw at the back of the tach. The tach now matches the laser tach at most RPM settings.


Jim
Sent from my iPad using Trawler Forum
 
Is it your engine hours or tachometer that is reading low? You can check the tach. It should have an adjustment on the back.

Hand Held Tachometer | eBay

Sorry - I re-read my post - it wasn't clear. It's the engine hours on my VDO tach that are reading 30% low and not the RPMs. They seem fine (though I've not checked).

Thanks

Richard
 
I use my HM on the VDO tach to do fuel calcs in my log. Run time and dipstick readings used to figure GPH, range, fuel buys, etc. I have not checked the HM against a clock. Will do next run. If it is off I'm going to be pissed.
 
Most VDO tachs with hour meters for our vintage boats have a DC driven hour meter. An easy way to check is to turn the key on and watch. You should see some movement. Our hour meter is powered by the same 12 VDC that is for the tach illumination.

I checked this morning. The hour meter only moves when the engine is running and not when everything is powered up with the engine stopped. I sat there for quite a few minutes with the oil warning alarm sounding just to find out!

Richard
 
My VDO will not clock the HM with ign on, engine off. Only starts clocking when tach gets an AC signal from the running engine.
 
Most stand alone hour meters do not operate as an electric clock would.

Power on it runs , power off it doesnt.

Many have a tiny motor that winds the clock for a few min of operation.

Usually it is 2 winds for a 1/10 of an hour.
 
Sorry - I re-read my post - it wasn't clear. It's the engine hours on my VDO tach that are reading 30% low and not the RPMs. They seem fine (though I've not checked).

Thanks

Richard

Richard, I have a portable digital laser tach onboard FW. I'd be happy to loan it to you next time we get together.

Sounds like your tach's hourmeter might run like airplane tach time runs...as a percentage of Redline/WOT.
 
Richard, I have a portable digital laser tach onboard FW. I'd be happy to loan it to you next time we get together.

Sounds like your tach's hourmeter might run like airplane tach time runs...as a percentage of Redline/WOT.
Al,

Thanks - I'll take you up on that offer.

I'm going to do some experiments at the dock to see if the hours meter is affected by RPM. I'll report back.

Thanks

Richard
 
jdud, does your boat have oil pressure/overheat alarms that sound when the key is turned on?

the alarms don't come on when I turn on the ignition key on but they will sound when I shut down the engine and don't turn off the key. My electronics only work when the key is on. When I was learning to use the GPS and sonar I had the key on and ran the hour meter up. I am at least the third owner and just bought the boat this season. I have no idea what the other owners did so I can't be sure of the hour meter.

This is my first boat and it is quite a learning experience.
 
This is my first boat and it is quite a learning experience.

Don't be so hard on the hourmeter. If yours was 100% spot on (the very best possible accuracy) and mine was a barely-believable 30% off, the mean would be 15% inaccuracy.

If you've got an average HM, you're within 15% of the extremes of practical accuracy.

If your engines surveyed well, are running well and the externals are in good shape, no worries! Relax and enjoy.
 
In the old days (1970's) The tach / hour meter was based on the engine running at 1800 RPM. Faster = faster hour meter. That's something to check.
 
In the old days (1970's) The tach / hour meter was based on the engine running at 1800 RPM. Faster = faster hour meter. That's something to check.

We had a 26' 1966 Chris Craft, a Chevy gasser. The tach was mechanical and the hour meter ran faster or slower based on our RPM's. We put a lot of hours on the engine trolling for salmon so who knew what the hours on the meter really meant. The hours never were questioned by the different surveyors and the new owner who we stayed in contact with for several years never mentioned it. Maybe because it was pre-internet. :)
 
An inaccurate hour meter is still fine for oil changes and other PM.
 

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