Intermittent tachometer-gctid812004

[CptCrunchie]

I'm having issues with the tach on my 2459. Most of the time it is good, but last time out, › the time it was bouncing between 2000 and 4000rpm. Looked at the engine, but with my limited mechanical ability, I glazed over and closed the cover. Know there is a lead - usually pink - that is attached somewhere in there, but I couldn't find it and had no desire to start tugging on wires.

Suggestions? Pictures with circles and arrows would assist greatly.

Failing that, is the tach something special, or would any tach that can be set to 8 cylinders work?

[Ruffryder]

Kevin, grey wire hooked up to your ignition coil negative (-) side.

Try cycling it on the back.

[CptCrunchie]

"Ruffryder" post=812006 wrote:
Kevin, grey wire hooked up to your ignition coil negative (-) side.

Try cycling it on the back.

Thanks, Joon, ....but what does cycling it mean? Please explain. You mean the 4-6-8 dial on the back of the tach ...if it has one?

[Chief_Alen]

yes move it back and forth a few times set it to the amount of cylinders you have.

[CptCrunchie]

That was weird. I'm used to the tach that have a 4-6-8. This one has a 1-2-3-4.

This is where it was set before I moved it. Yes, the arrow is pointing down opposite the 4.



But when I went to turn it, it would only go this far one way,......



....and this far the other.



I left it this way.

Anyone know what all this means?

[Four_Pyrates]

Most of the bouncing in the tach is caused by corrosion. It doesn't take much. Just unplug the connectors and clean them or in most cases, just plug them back. Now for the magic trick....If the tach is usually ok, it might have a bit of moisture corrosion inside..When it jumps, thump the glass with your finger and see if that fixes it. That jars the very small corrosion causing the electrical shorts. Also, reset the back button to where it was. Now, before you laugh at the "thumper method", I learned it right here from the one of the best marine mechanics who ever lived. Good luck.

[Norton_Rider]

"Four Pyrates" post=812118 wrote:
Most of the bouncing in the tach is caused by corrosion.

+1

Most Bayliners use a molded plug that is a friction fit on the threaded terminals on the back of the tachs. Corrosion builds up inside this connector, particularlt intermally, where the wires are molded-in. The best way to take care of the problem is to cut the connector off, crimp-on ring terminals on the wires, and attach them to the tach terminals with brass nuts and washers. In many cases, the terminals have different diameters. Make sure that you check this before you buy ring terminals and nuts.

[CptCrunchie]

"Norton Rider" post=812135 wrote:

"Four Pyrates" post=812118 wrote:
Most of the bouncing in the tach is caused by corrosion.

+1

Most Bayliners use a molded plug that is a friction fit on the threaded terminals on the back of the tachs. Corrosion builds up inside this connector, particularlt intermally, where the wires are molded-in. The best way to take care of the problem is to cut the connector off, crimp-on ring terminals on the wires, and attach them to the tach terminals with brass nuts and washers. In many cases, the terminals have different diameters. Make sure that you check this before you buy ring terminals and nuts.

Found it! Again, thanks!

[CptCrunchie]

I still need to know what the 1-2-3-4 dial is supposed to be set at for an 8-cylinder engine. Before I touched it, the arrow was pointing away from the 4. But if I turn the dial all the way clockwise, it almost points to 1. All the way counter clockwise has it pointing away from the 3. I would think it needs to be turned all the way clockwise, ....but not being mechanically minded, that's only a guess.

Two questions:

QUESTION 1: Are these tachs used for bigger engines than an 8 cylinder ......like a 12 cylinder? I ask because I can see the 1 being for a 4 cylinder, the 2 being for a 6 cylinder, and the 3 being for an 8 cylinder. What then would the 4 be for?

QUESTION 2: Is there problem with turning the dial with the engine running? I'm thinking about taking it out and turning the dial until the tach looks like it is registering correctly, but am not sure if I would short something out doing that.

[Ruffryder]

Not used for 12cyl,

Usually 1 for OB, 2-4cyl,3-6cyl, 4-8cyl

Try setting it at 4.

No problem turning the dial when running.

[Neo]

Start with a good ole continuity test from Tach back to coil. I had intermittent issues turned out to be a loose pin in the harness.

[CptCrunchie]

It is fixed and working perfectly. Thanks everyone!