Tachometer needle broken - help

[smokey73]

Yanmar 4JH2E on a 1994 Hunter 40.5

Yesterday I noticed the needle on my tach was broken. The tach works fine and the Yanmar runs great. Just hard to tell accurate RPM.

Does anyone know of a fix for this, where to get parts and if the tach can even be opened and the needle replaces if I can source one? Any tips, or sources would be appreciated. If I have to replace the Tach is there a replacement other than the Yanmar tach.

 

[Ralph Johnstone]

Glue a toothpick to the stem of the tachometer.

Barring that, purchase a VDO tach. Here is the one I installed a few years back. It accepts all inputs. See the installation guide. If you have an optical tach ($15-$20) as it provides the easiest install.

Lastly, install a Sunbrella cover over your instrument panel and save your next tach and maybe a few other instruments before they disintegrate from the UV.

 

[kloudie1]

The tach can be repaired, but it is a fiddly, tedious job that requires a lot of attention to detail. The instrument can be removed from its case and then the face is accessible.. carefully remove the back part of the needle then use something like 5200 to repair it. You may have to wrap a piece of thread around the needle base to keep it together. .. Probably not worth the investment in time compared to Ralph's suggestion. The problem is that the needle has become very brittle from UV and cracked from the stress of the push-fit onto the shaft.. A new one is the best fix..

 

[smokey73]

Thanks @Ralph Johnstone - do you have the model number of the gauge you installed? I don't see it on the document you sent. Does it fit nicely into the existing opening.

Thanks @kloudie1 I wasn't sure if the face could be removed from the gauge but the price on the vdo gauge is not too bad.

By the way. I always keep my binnacle covered with a sunbrella cover when I'm not sailing and have done so since 2012. I am not sure what the PO did but the cover came with the boat.

 

[Rich Stidger]

I have a source. I will get back to you later today. Stay tuned.

 

[smokey73]

I have a source. I will get back to you later today. Stay tuned.

Standing by

 

[Rick D]

There are instrument repairers for classic cars and aircraft that could probably handle that. FWIW.

 

[Ralph Johnstone]

do you have the model number of the gauge you installed?

The model is the name of the file: Vision Series 333-163 and yes, those instructions are general for all VDO tachs. Dimensions below. Hit GOOGLE and find the lowest price you can find. Seem like everyone sells them on line. I seem to remember the lowest was about $99.99 and was a nickel cheaper that its closest competitor. I was lucky in that the VDO fit the original tach opening.

 

[Rich Stidger]

Dan,
Here is the tach that I purchased in Dec 2021. My Volvo MD22L-B has a red line of 3000 rpm, so this tach was perfect. The diameter of the tach body was 85mm and I had to fudge a spacer because Volvo uses a slightly larger tach body, probably to discourage replacements with non-Volvo parts. You may not have that issue with a Yanmar panel.

Be sure to identify the wires on your existing tach so you can match the corresponding connections on the new tach.

This tach as well as most similar replacements are fully programmable in terms of pulses per rpm. An optical tach is the very best way to calibrate it.
If your Yanmar runs over 3000 rpm, I am certain that you can find 4000 rpm units on eBay.

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Attached are the programming instructions for this tach. I have other instructions for slightly different tachs as well, so ask if you need something.

 

[seadaddler]

I replaced my tach with VDO replacement years ago the Yanmar tach was crazy $$$$ and called VDO for info on replacement and found what I needed maybe $109.00 and been working perfect

 

[smokey73]

Thanks all! I am probably going with a VDO replacement tach once I get back to the boat and determine the size I need and what sensing mechanism it uses.

 

[Ralph Johnstone]

and what sensing mechanism it uses.

The VDO Vision Series 333-163 will run off anything that's attached to your engine alternator, flywheel, radiator cap, hub cap, anything. Check the instruction manual for sources of signal.

 

[smokey73]

Thanks @Ralph Johnstone Sounds like the way to go.

 

[smokey73]

OK, I have the programmable tach. VDO no longer makes tachs mentioned and a company called Veratron bought out the rights to manufacture them but they look like they are identical, including the programming.

However, I need the pulse per revolution (PULSE value) in order to start the programming? Does anyone have that value for a Yanmar 4JH2E?

I've also posted this in a new question since it might not get the views buried in this thread.

 

[Rich Stidger]

Easy. First measure the diameter of the alternator pulley and the diameter of the engine crank pulley. Divide the engine diameter by the alternator diameter. This gives you the number of revolutions of the alternator for each revolution of the engine.
Now you need to know the number of poles in your alternator. You should find that in the alternator specs. Multiply the number of poles by the number of alternator revolutions and the result will be the number of pulses per engine revolution.
Easy peasy.

 

[Ralph Johnstone]

However, I need the pulse per revolution (PULSE value) in order to start the programming?

Damn, not to sure what I had for breakfast this morning and I CANNOT remember if I used pulses / revolution 15 years ago. If you've got a cheap optical tach, you can easily set it with that. I check the accuracy of the VDO tach every 5 yrs ± using the optical tach and it changes very slightly.

Rich's method is right on (if you're overly energetic ) but I save my energy for biking in the summer.

This one looks identical to mine and it's super cheap from Amazon.com :

 

[smokey73]

@Rich Stidger and @Ralph Johnstone - Thanks. So you are saying that for a Yanmar 4JH2E the tach sensor comes off the Alternator and not from a flywheel sensor? I was sitting at home figuring out the wiring on the back of the Veritron (no longer made by VDO) at home and couldn't trace the wires on the boat from my LazyBoy. It would seem you need to get "close" to the right pulse value to get started. My Yanmar manual just shows a "sensor" but not source of the sensor (ie alternator or flywheel). A couple of questions for you as the installation manual for the Veritron is terrible.

1. If you disconnect the battery are you required to reprogram the tach - the instructions say "Please note that when you disconnect the battery, all volatile electronic memories lose their input values and must be reprogrammed" They don't say what is in volatile memory though!

2. They don't discuss "calibration" in the instructions. The only thing I see in the manual that can be changed to affect the tach reading is changing the PULSE value that is done in the Configuration step. Is that correct. The problem is that you have to disconnect the config

If either or both of you could give me a call I'd really appreciate it. I'll pm both of you with my phone number.

 

[Ralph Johnstone]

The only thing I see in the manual that can be changed to affect the tach reading is changing the PULSE value that is done in the Configuration step.

Aw crap, that's not very nice. Sounds like a whole new set of rules for this model of tach.

"Please note that when you disconnect the battery, all volatile electronic memories lose their input values and must be reprogrammed"

This keeps getting worse. I haul out and wrestle with my batteries all the time just to keep in shape and the tach hasn't lost anything in the way of calibration memory.

Please post your tach installation instructions so we can digest them before diving into this. Actually, sounds quite interesting .

 

[smokey73]

@Ralph Johnstone Here is a link to a copy of the installation instructions. It is directly from the Veratron site but it still says VDO. I couldn't get the file to allow me to save it so I am sending the link. On this page, just click on "downloads" then click on "manual" and then select the english version. Hope that works.

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For the record, I went to the boat and the Tach sensor for my 4JH2E comes off the flywheel, not the tach. Here is a picture of the tach sensor on my bell housing. The orange wire with the two blue marks just to the left of the clear drain hose attaches to the sensor. There is a similar marked orange wire going into the tach. Now I need to figure out how many teeth are on the flywheel or how many pulses are produced per revolution.

 

[Rich Stidger]

Dan,
Here is a link to your Yanmar Service manual. On page 2-28 it states that the ring gear has 127 teeth. You're welcome.

Download Yanmar 4JH2E Service Manual | ManualsLib

www.manualslib.com