4210 Tachometer Problem....

[pilot-werx]

Noticed while snowblowing the other night the tachometer was all over the place. It would read 2200 rpm then drop to nothing. Just kept going back and forth. In looking at the tech manual it appears the tach gets its speed reading from the alternator?

Any ideas what could be wrong?

Thanks!

 

[mfreund]

It could be a bad battery, loose ground connections, or alternator going out to name a few. I would do the cheap things first. Give it a good look over and tighten all battery and ground connections.

 

[atschirner]

There was a post last year about snow plowing and alternator problems. If memory serves the alternator belt was getting wet with melted snow and slipping on the alternator pulley. It's one of those "perfect storm" opportunity; high current demand, wet belt and a tach that uses the stator AC to indicate RPM.

I hope you find the fix to be a cheap one.

 

[jdgreg]

There was a post last year about snow plowing and alternator problems. If memory serves the alternator belt was getting wet with melted snow and slipping on the alternator pulley. It's one of those "perfect storm" opportunity; high current demand, wet belt and a tach that uses the stator AC to indicate RPM.

I hope you find the fix to be a cheap one.

Hmmmm, very interesting. When I started plowing saturday am during the storm, the tach on my 4210 was acting up too. It was behaving like a sticking cable. I had left it out over night uncovered (I usually keep it in the barn) so it would be close to the house. When I got done plowing for the day I tried to restart it later than evening, the battery acted very weak and it wouldnt turn over. The next day, it cranked over just fine, and the tach worked like it was supposed to. I had been running all the lights, as well as a small 12V ceramic heater in the cab, so there was obviously some drain. It never felt or sounded like the belt was slipping, but it makes perfect sense. Thanks for posting this.

 

[GoodGuy]

Same situation with me the other night. I dropped to idle to grab my coffee and when I throttled up the tach stayed at idle. I noticed that when I was at around 1800 rpm it would sometimes show 900 and then 1500 back to 900 and then up to 1800 and stayed there. Hmmm.... I'll have to check the belt tension and alternator with a volt meter. Please share any info if anyone finds anything definitive.

 

[pilot-werx]

This one has me stumped.. I can see the belt slipping with the snow.

I just put in a new optima battery a couple of weeks ago and cleaned up all of the terminals. Tonight I unplugged the tach wires at the alternator and lubed them really well. The tach seemed normal tonight. I will check the belt tomorrow and replace and/or tighten if need be.

Thank you for some pointers!

 

[pilot-werx]

There was a post last year about snow plowing and alternator problems. If memory serves the alternator belt was getting wet with melted snow and slipping on the alternator pulley. It's one of those "perfect storm" opportunity; high current demand, wet belt and a tach that uses the stator AC to indicate RPM.

I hope you find the fix to be a cheap one.

Looks like you are the winner.... Before going out yesterday, I snugged up the alternator belt and did not have one problem.

Thank you for the tip!!!

 

[atschirner]

Glad to help. Have a Happy New Year.

 

[mfreund]

Glad it was cheap!!

 

[pilot-werx]

Honestly, I would have never guess it would be the belt. It felt tight but.... I snugged it up a little more and the problem went away... Cheap fix for sure which is a rarity for me...