Tack problem

[Jack Hutteball]

I spent the day changing all the oil, oil filter, fuel filters, and transmission fluid... fun day.  Ran the engine in gear for about 20 minutes to make sure that everything was operating correctly and no leaks anywhere.  Set the engine rpm's about 1500 and let it run while I checked and cleaned things up.  When I went to shut off the engine I noticed the tack was reading 2800 which was a surprise, as the engine speed had not changed.  When I throttled back the tac stayed at 2800.  IF I throttle up the tack would go above 2800, but then stop at 2800 as I throttled back to the lowest speed.  Turned the engine and key off and the tack stayed ay 2800.  Tapping on the glass resulted in no change.  I started and stopped the engine several times, same result.  All the other gages are working fine.

Broken tack?  I assume that if it is an electrical problem the needle would return to 0 with everything off.

Jack Hutteball
Mariah lll

[Footloose]

Let me take a stab at this.  The tach runs off the alternator.  Are the alternator working and voltage regulator functioning properly?  I would check the connections on both of these.  The assembly at the factories is less than ideal.  I have had issues with these that are repaired by proper stripping and crimping.  If everything checks out I would pull the panel in the cockpit and check those connections.  Not sure how to check if the tach is functional, but someone will.  My bet is that with all of the filter/fluid changes something was bumped or pulled and is making a poor connection,

[Jack Hutteball]

The alternator is working as I see 14 volts on the volt meter on the panel, so also assume the regulator is doing it's job.  Does not seem like there is any wiring on the front and sides of the engine I was working on.  There is a bundle of wiring that comes across the back of the engine that goes to the fuel pump that I may have jostled while getting the funnel into place to refill the transmission.  Will check in that area and open the panel and check the back of the tack.

Jack

[Stu Jackson]

http://www.c34.org/wiki/index.php?title=Manuals

Scroll down to Teleflex Tach Manual.

[Jack Hutteball]

Thank you Stu.  Gave me the areas to check connections.  Did that and everything looked clean.  Needle still stuck with power off.  Fellow boater said he had tack problems and thought my problem is probably corrosion inside the meter as he has had the problem on his Island Packet.  Tapped the back of the tack several times, turned on the key, and the tack went to 0!  Turned the key on and off and it stayed at 0.  Ran the engine rpm's up above where the tack was stuck and it hesitated at the spot coming back down, but did return to idle ok.  Tapped the back of the tack several more times and now it seems to be working without a hitch at all rpm's.  I know there is moisture inside the gauge as it always condenses on the glass on all my meters after the lights are on for a few minutes.  At this point I will just watch and see what happens.

Jack

[Ron Hill]

Jack : You may want to check your instrument lights.  The reason they are ON when the panel is turned ON is so the heat from the lights evaporates that condensation.

You might also read my Mainsheet tech note article on installing LED bulbs.  I installed red LEDs
I found that over time the 194 instrument lights were tooo hot and burning the bulb holders and the instrument case they screw into!!

A few thoughts

[Jack Hutteball]

Thanks Ron, I remember your article on that now, but I had forgotten about it.  That will go to the top of my list.
Jack