RPM - Am I imagining things?

[big bubba]

graphite lube is also an option, but don't mix w/grease!

 

[jshwhite]

Got a chance to check the rpm with my new tach - what a great little tool. Glad I got it.

I was right - it's running about 200-300 rpm faster than the dash shows.

I pulled the cable and lubed it, although I don't think it needed it. It was spinning freely. Put it back in and it's doing the same thing.

So, now what. It's got to either be the drive or the dash. Any ideas? I don't really feel like throwing parts at it, as they cost $$ so I'd like to have a good reason to replace something.

 

[kuboman]

Likely is the tachometer head that is the problem. If you can get it out sometimes a drop of oil on the input drive helps otherwise is will be the mechanism inside that is worn or sticky. Taking them apart usually results in breakage and you end up buying new anyway.:laughing:

 

[jshwhite]

Likely is the tachometer head that is the problem. If you can get it out sometimes a drop of oil on the input drive helps otherwise is will be the mechanism inside that is worn or sticky. Taking them apart usually results in breakage and you end up buying new anyway.:laughing:

Thanks, I'll give it a shot. If it breaks I guess that's the part I have to replace

 

[jshwhite]

Oiled the drive and still no luck. Think it's time for a new drive?

 

[jshwhite]

I just replaced the tach drive (on the engine) and still no go - reading 300 over what it's running. Any suggestions? I REALLY don't want to replace the dash.

 

[Blkvoodoo]

I just replaced the tach drive (on the engine) and still no go - reading 300 over what it's running. Any suggestions? I REALLY don't want to replace the dash.

I'd check other tractors too see how accurate they are. A couple hundred rpm one way or the other isn't really an issue, I'd be surprised if it wasn't some what a " designed in feature " too keep operators from over speeding the engine

Is the rpm discrepancy constant thru the rpm range ? Or just at full throttle ?

 

[Bluegill2]

It's usually always the tachometer and rarely the other end.

I go more by how my engine sound and never run full throttle

 

[SPYDERLK]

Got a chance to check the rpm with my new tach - what a great little tool. Glad I got it.

I was right - it's running about 200-300 rpm faster than the dash shows.

I pulled the cable and lubed it, although I don't think it needed it. It was spinning freely. Put it back in and it's doing the same thing.

So, now what. It's got to either be the drive or the dash. Any ideas? I don't really feel like throwing parts at it, as they cost $$ so I'd like to have a good reason to replace something.

Have you verified that it is intermittent? ... If so it may be vibration related - a load and rpm function. Try damping the tach body w your hand when the rpm offset occurs.
larry

 

[Deano]

It's usually always the tachometer and rarely the other end.

I go more by how my engine sound and never run full throttle

I tend to agree with this post on your issue.