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H2814D 03-12-2012 03:51 AM

Changing Out Engine Gauges/Tach Problem
So I have money to spend and I want to improve some of the cosmetics of the boat. I want to change out the Tach, Fuel Gauge, Water Temp Gauge, and the Ignition Switch on a 1979 Islander Bahama 30. The Engine is a Volvo Penta 2 cylinder diesel (MD7A).

Right now the tach does not work and there is no movement at all. I checked the AC voltage coming off the sender while the engine was running and only got .025-.049 VAC on the tester as I increased throttle. The voltage did increase, but is it supposed to be this low? I couldn't find an internet source to tell me what the expected voltage should be, so I don't know if this particular part is working properly or not. Does anyone know what it should put out? I also checked for 12 volts DC at the tach and it is there, so i am thinking it is either the sender or the tach...thus the reason to change it out.

The current tach only goes up to 2000 rpms (2 cylinder diesel). It is run off magnetic sending unit screwed into the block. If I can use a tach with a different sending unit source that would be easy enough for me to hook up, I wouldn't be opposed to doing so.

Now does anyone know where I should look for the replacement equipment? The only gauge that worries me is the tach, since I guess I have to match that. The other gauges are pretty much simple. I want all white gauges, since I am about to brighten up the plastic mount with a coat of white spray paint and think it would look good with white gauges on a white mount. It is currently a dull, weather-beaten black mounting box.

Anyone have any experience with this? Thanks in advance for any help you can give me.

H2814D 03-12-2012 02:48 PM

Re: Changing Out Engine Gauges/Tach Problem
My error in my previous post. The tach goes from 0-3000 rpm's. I reported 0-2000 earlier.

H2814D 03-13-2012 05:01 AM

Re: Changing Out Engine Gauges/Tach Problem
Can anyone give me an idea as to whether the ac voltage of .025-.050 (from low idle to high) from the sending unit mounted into the side of the engine is enough to power an older VDO tach, or a replacement new one? I want to change out the tach and other instruments, but want to get everything purchased and available before I go back to the boat to do the install. I don't know if the sending unit is actually working or not. Maybe someone is willing to voltage test their sending unit for me?
Volvo-Penta MD7A....anyone? :-)

NCboatrx 03-13-2012 08:09 AM

Re: Changing Out Engine Gauges/Tach Problem
I suggest that you contact Dick Vosbury of Vosbury Marine in Annapolis. He is the go to guy for Volvo parts and information.

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