I have a 2001 Mainship 390 with a single Cummins 6BTA engine. After having an annual service done on the engine, my tachometer stopped working. The sending unit is a magnetic sensor on the flywheel. The mechanic suggested that the sending unit was failing. I replaced the sender, but still get no readings at either helm station. Any suggestions?
tachometer issue
- Thread starter ifxubak
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Comodave
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I would check all the electrical connections.
I had intermittent / no reading and found it to be the elec connectors at the sending unit. Cleaned them up and back to normal.
The sender needs adjustment but you need to understand the correct procedure before making any adjustments.
The sender needs adjustment but you need to understand the correct procedure before making any adjustments.
jgwinks
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"after having an annual service done". Does that mean it worked before the service but didn't work on the first start after? If so I'd guess a wire got dislodged someplace. These things are almost always wiring problems.
PhilPB
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Very much agree. When I had annual service done last year, the mechanic, by bracing his foot on the engine ended up shorting the signal wire to the starter. It took a lot of time and money tracing down the problem and the fix was very easy. I have learned that if something worked before and no longer doesn’t, what changed and what was the last thing done. That's the first thing I consider in my search for resolution.
C lectric
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XFXUBAK
Did you run the sensor in untill it touched the flywheel, then back it out between 1/4 and 1/2 a TURN and then snug up the nut? THis is the required adjustment for the sensor to be able to pick up then pulses from the flywheel.
Was there any rust showing on the sensor end. If so the rust MUST BE CLEANED OFF as it is magnetic and will degrade the pulses so the sender is not sending a good clear pulse to the tachometer.
Unless this is done it won't work.
Note to that these pulse are weak so the wiring MUST be in good shape with clean and tight connections. It takes very little oxidation at connections or crimps to degrade the signals so the meter cannot read them.
Did you run the sensor in untill it touched the flywheel, then back it out between 1/4 and 1/2 a TURN and then snug up the nut? THis is the required adjustment for the sensor to be able to pick up then pulses from the flywheel.
Was there any rust showing on the sensor end. If so the rust MUST BE CLEANED OFF as it is magnetic and will degrade the pulses so the sender is not sending a good clear pulse to the tachometer.
Unless this is done it won't work.
Note to that these pulse are weak so the wiring MUST be in good shape with clean and tight connections. It takes very little oxidation at connections or crimps to degrade the signals so the meter cannot read them.
stevensibs
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C lectric, or anybody else that can help, I have a lugger 6414 and it has 3 hours on it since total rebuild. It has a new magnetic sensor drilled and tapped into the flywheel and it connects to a brand new Faria programmable tachometer. When I start the motor, the tach does it's self test by needle going full to max and back to zero but no rpm's, and the tach is keeping track of engine hours properly. Could the sensor be faulty even though new? The sensor is as close to flywheel as possible. 129 teeth on the Twin Disc. Any ideas? Thx.
C lectric
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QUOTE: The sensor is as close to flywheel as possible. END QUOTE
What is as close as possible? Unless the adjustment is done as described above it may not may not work except intermittently.
Check the adjustment as I described. Also check for any rust matter stuck on the probe.
If it still does not work then maybe the wire is not making a good connection. ALL connections must have good, clean wire, crimps, continuity through to and including the guage connections. I have used a product called NoAlox for years to coat the wire before insertion into the crimp barrel to prevent oxidation of the connection. I also now use a dielectric grease. Also on the actual contact areas of the screw terminals.
The voltages involved are not strong so can be easily blocked with questionable connections.
Yes , it is possible that the sender OR the guage itself is goofy but untill you are positive about the wiring not being the problem do the needed checks and confirmations first.
What is as close as possible? Unless the adjustment is done as described above it may not may not work except intermittently.
Check the adjustment as I described. Also check for any rust matter stuck on the probe.
If it still does not work then maybe the wire is not making a good connection. ALL connections must have good, clean wire, crimps, continuity through to and including the guage connections. I have used a product called NoAlox for years to coat the wire before insertion into the crimp barrel to prevent oxidation of the connection. I also now use a dielectric grease. Also on the actual contact areas of the screw terminals.
The voltages involved are not strong so can be easily blocked with questionable connections.
Yes , it is possible that the sender OR the guage itself is goofy but untill you are positive about the wiring not being the problem do the needed checks and confirmations first.
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