All, I need help. I have a Yanmar 2QM15 on an 1981 Hunter 30. It never had a tach. I would like to add one. I have found the sender and the meter for $120 & $300 respectively. That is more than I bugeted. Anybody have a source for less expensive solution?
Tach for a Yanmar 2QM15
- Thread starter Texas Lake Sailor
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I picked up a used tachometer with an hour meter at Don's Marine Salvage for about $30 and had my rebuild alternator shop add a wire "tail" to the alternator to send out. Don's has shipping and may be worth a call.
http://www.donsmarinesalvage.net/
http://www.donsmarinesalvage.net/
Tach possibilities
Tachometers are fairly simple, so if you have electronics chops, you have a few options:
Sensor
- best and easiest is to buy a proper tach sensor for the engine. One might already be on the engine.
- It's also possible to make an optical pickup, or put a very small magnet on the flywheel and fabricate a Hall-effect sensor, but it's not for the novice.
-[edit] as per paul F, the alternator output is also a possible source for the tach signal
Instrument/meter
- an inexpensive auto tach might do. You might need to buffer or amplify the sensor signal
- try to find a used boat tach or electronic speedometer. (I've bought salvaged but working speedometers for $1 at marine flea markets, and I got a new surplus one for $10). Both tachs and electric speedometers work by converting the frequency of pulses to a meter reading. Again, you might need to add a buffer to match the pickup to the unit, or "prescale" the pickup output for a speedometer by using logic ICs to divide the frequency down. Most speedometers are adjustable, but you might also need to re-label the display.
- there are many DIY tach projects out there, including microcontroller-based units with digital output.
Tachometers are fairly simple, so if you have electronics chops, you have a few options:
Sensor
- best and easiest is to buy a proper tach sensor for the engine. One might already be on the engine.
- It's also possible to make an optical pickup, or put a very small magnet on the flywheel and fabricate a Hall-effect sensor, but it's not for the novice.
-[edit] as per paul F, the alternator output is also a possible source for the tach signal
Instrument/meter
- an inexpensive auto tach might do. You might need to buffer or amplify the sensor signal
- try to find a used boat tach or electronic speedometer. (I've bought salvaged but working speedometers for $1 at marine flea markets, and I got a new surplus one for $10). Both tachs and electric speedometers work by converting the frequency of pulses to a meter reading. Again, you might need to add a buffer to match the pickup to the unit, or "prescale" the pickup output for a speedometer by using logic ICs to divide the frequency down. Most speedometers are adjustable, but you might also need to re-label the display.
- there are many DIY tach projects out there, including microcontroller-based units with digital output.
Have you considered a Tiny-Tach? I think I will be getting one for my YSM12.
http://www.tinytach.com/tinytach/diesel.php
http://www.tinytach.com/tinytach/diesel.php
I presume this is a diesel engine.
The center of your alternator provides tech signal. I believe it is the "W" terminal. It provides un-rectified AC voltage so the tech can count the pulses. If it doesnot have one, it only cost a few dollars for any automotive electric shop to solder one in your existing alternator for you. All diesel truck uses the same setup.
You can buy a tech from truck supply shop for diesel trucks or marine place. Teleflex make great ones. I replaced my old one with a Teleflex which comes with a running meter.
The center of your alternator provides tech signal. I believe it is the "W" terminal. It provides un-rectified AC voltage so the tech can count the pulses. If it doesnot have one, it only cost a few dollars for any automotive electric shop to solder one in your existing alternator for you. All diesel truck uses the same setup.
You can buy a tech from truck supply shop for diesel trucks or marine place. Teleflex make great ones. I replaced my old one with a Teleflex which comes with a running meter.
Matching tachometers that count frequency to an engine is a p.i.t.a. Not only to you have to make sure that the new tach is setup for your pulleys, you have to make sure it is set up for the same number of poles in your alternator.
Nigel Calder states that "programmable" tachometers can be used universally. However, I am not sure what a programmable tachometer is.
Nigel Calder states that "programmable" tachometers can be used universally. However, I am not sure what a programmable tachometer is.
I bought a VDO programmable tach on eBay including shipping for $20. With a very slight modification it fit in my panel perfectly.
A programmable tack is one that you can adjust the number of pulses per rpm of the engine. It is necessary so that you can adjust for the number of poles in the alternator and the pulley ratio of the engine to the alternator. You need an optical tach (borrow or buy for about $25) to calibrate.
See pix below for old and new.
A programmable tack is one that you can adjust the number of pulses per rpm of the engine. It is necessary so that you can adjust for the number of poles in the alternator and the pulley ratio of the engine to the alternator. You need an optical tach (borrow or buy for about $25) to calibrate.
See pix below for old and new.
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...that was a good buy Rich......
i just bought a used panel on e bay last week and gave $100.00 pluse some shippingi needed some of the orther things in the panel so i just bought the hole thing .....that was good for me......i also need the tach pickup for the flywheel and found one that is the same thread size as the yanmar at a local NAPA store for $29.00...so now i am not sure if i have to add anything to the flywheel to make it pulse or not ....usealy when useing a proximity switch there has to be some thing to break the circle in order to make it pulse so i ahve some more research to do i think..... pic below
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Not sure what the best method is....
Just learned that my tach is showing 1/2 of the actual RPs's. Had a tech test the RPS's and my tach was exactly 1/2.
The tach was on my boat when I got it used but it looks like it was factory, in a Yanmar panel. Hunte 31, 1984.
Are there any ways to adjust this?
Just learned that my tach is showing 1/2 of the actual RPs's. Had a tech test the RPS's and my tach was exactly 1/2.
The tach was on my boat when I got it used but it looks like it was factory, in a Yanmar panel. Hunte 31, 1984.
Are there any ways to adjust this?
What model engine do you have?
You could get some witeout and re-label the meter
Some tachs are adjustable but I'd expect that the range would be less than 2:1. If this is a retrofit to the alternator, there might be a rectification issue - full-wave vs half-wave.
Anyways, the math isn't too tough, so having to mentally multiply tach readings by two might be a reasonable workaround til the issue is resolved.
Probably not a bad idea to exercise the mind... now if I can only distinguish from M and S in RPM!What model engine do you have?
You could get some witeout and re-label the meter
Some tachs are adjustable but I'd expect that the range would be less than 2:1. If this is a retrofit to the alternator, there might be a rectification issue - full-wave vs half-wave.
Anyways, the math isn't too tough, so having to mentally multiply tach readings by two might be a reasonable workaround til the issue is resolved.
If you can't find a good programmable tach on eBay, bight the bullet and buy the $180 farr programmable tach from West Marine. When you need it, you need it. You will need to know the # of poles in your alternator and the pulley ratios on the engine and alternator. The farr tach also comes with an hour meter. The Farr tach has a bank of dip switches that you configure based on the # of poles and puley ratio. You won't even have to calibrate the tach--it will read true.
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