Tachometer swap / repair

[Yellovette]

I have a brand new tach for my 99 380DA, which I intend to swap for the starboard one which is erratic and working correctly only part time. My concern is that the new tach has 0 hrs. showing for run time and I would really like to have the correct engine hrs. on it.
Has anyone ever dealt with this? Is there a way to run up the hour meter? A buddy suggested connecting the 12v power to it, (on the workbench) and just letting it sit for the required (580 hrs).
Any help would be greatly appreciated.

Yellovette, (Ed)

 

[Cory Tanner]

I believe putting power to it will get the hr meter rolling. That is almost a month sitting on a bench though.

 

[boatrboy]

I kept my old tachometer and documented when I replaced the tachometer in my maintenance books. When I sold the boat I told the buyer and provided the old tach during the purchase.
I do think the hours in the controller are not resettable so a scanner should always show the correct hours.

 

[dtfeld]

Before replacing, there are a couple selector switches on the back. You can turn them with a small screwdriver and they usually will start working again. However, they are notoriously inaccurate.

With the CAT's, most of us have upgraded to the Aetna tachs. They are much more accurate (+/- 1RPM). Skip the teleflex, and get some Aetna's

https://www.aetnaengineering.com/model-8905r-lcd-tachometer

As mentioned, just keep track of the Hr reading on the old tach and document the change.

380 with 3116's is a SWEEET boat!!!

 

[Yellovette]

Thanks for the comments. I realize 580 hrs would be a month on the bench, but if it works that would be ok. I'll check out the selector switches and see if they do anything to correct the erratic behaviour. The problem with going to the Aetna units is that when I bought the boat I was provided with a brand new replacement tach, so I'm reluctant to spend $700 for a new set without using what I have. Regardless, I'd still have engine hour issue x 2. I know I can always document the hr. changeover and may have to do that at some point.

 

[dtfeld]

You can alway install a hobbs meter on the engine and use that.

 

[mrsrobinson]

I kept my old tachometer and documented when I replaced the tachometer in my maintenance books. When I sold the boat I told the buyer and provided the old tach during the purchase.
I do think the hours in the controller are not resettable so a scanner should always show the correct hours.

Same, did this on the 330 so there would be no issues with the next buyer.

 

[Sgrochow]

Thanks for the comments. I realize 580 hrs would be a month on the bench, but if it works that would be ok. I'll check out the selector switches and see if they do anything to correct the erratic behaviour. The problem with going to the Aetna units is that when I bought the boat I was provided with a brand new replacement tach, so I'm reluctant to spend $700 for a new set without using what I have. Regardless, I'd still have engine hour issue x 2. I know I can always document the hr. changeover and may have to do that at some point.

It works for sure, did mine over the winter when boat was laid up. I'm quite absent minded so I put a note on my calendar to remind of the end date so I wouldn't go over.

 

[Yellovette]

I'm not worried about convincing the next buyer that I have more hours than what's showing on the stbd meter. Usually if anyone is going to be dishonest, it is to show less hours rather than more. I can also point to the port engine hours, as I always run both engines together. I suppose its just me being anal wanting to have a correct reading on both tachs.

I'm going to try energizing the tach and see what happens. There's a sender, ignition and ground terminal. Not sure if I will need to connect to just ignition, or sender or both (as well as ground of course).

 

[Yellovette]

It works for sure, did mine over the winter when boat was laid up. I'm quite absent minded so I put a note on my calendar to remind of the end date so I wouldn't go over.

Oh very cool! What terminals did you connect to??

 

[Sgrochow]

Oh very cool! What terminals did you connect to??

It was a few years ago, I don't recall. Pretty sure I used a multimeter to ID + and - with engine running before removing.

 

[Yellovette]

Sorry, I don't mean to beat up this topic, but I'm just wondering whether anyone who had been experiencing problems with their tachometer actually found the cause to be the sender unit on the flywheel? I would hate to assume the tach is faulty when its actually a malfunctioning or dirty sender. I note that cleaning the sender is actually a periodic maintenance item in the maintenance manual.

 

[Mauler34Rod]

Following…..

 

[SamG]

I have a brand new tach for my 99 380DA, which I intend to swap for the starboard one which is erratic and working correctly only part time. My concern is that the new tach has 0 hrs. showing for run time and I would really like to have the correct engine hrs. on it.
Has anyone ever dealt with this? Is there a way to run up the hour meter? A buddy suggested connecting the 12v power to it, (on the workbench) and just letting it sit for the required (580 hrs).
Any help would be greatly appreciated.

Yellovette, (Ed)

There is a quick fix for the erratic tach.
On the back there is a switch that turns with a screw driver. It selects 4-6-8 cylinders. Turn clockwise and counter clockwise a few times and back to original position. That cleans the oxidation and the tach will be fine.