# Yanmar with aftermarket tach and temp guage



## Northeaster (Jan 13, 2007)

I am tying to connect the following equipment to my Yanmar 2gm (1982), and am looking for advice. Thanks in advance!!:

1. Diesel electrical (Faria) tach. Although my panel doesn't have a tach, i do have the tach sensor, on the engine, and wiring going to the panel (unconnected). Yanmar manual shows 2 wire s(orange and blue/red), form the sensor, connecting to the factory tach, plus power and ground. My new Faria tach only has connectors for power/ batt, ground, and one signal (not 2). Anyone know if I can make this work? I tried each of the 2 sensor wires separetly, but with no luck.

2. Aftermarket temp gauge. I tried splicing into the temp sensor wire, where it connects to the temp alarm lamp, in addition to connecting the guage to power and ground, but with no luck either. Thoughts? Would the sensor signal used for the alarm lamp and buzzer be "graduated" to work with a guage, or would it be a threshold type signal only??


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## Boasun (Feb 10, 2007)

Did you get the senders to go with the tach and tempt gauges??


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## Northeaster (Jan 13, 2007)

No, I did not get any senders with the tach. Is it normal that they come with their own?? I ask this because I "thought" I got a deal on an open box tach, but nothing came with it. I could have paid $30 more for one with a box - and maybe other parts??

The sender i have is the Yamnar original - the boat just came with the cheaper panel - no tach.


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## Boasun (Feb 10, 2007)

Some tachs can be used with any sender and then some have to be matched up with the correct one. Same with other gauges that we use on our boats


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## sailingdog (Mar 19, 2006)

Northeaster-

Unless you know what you're getting, I'd highly recommend avoiding "open box" deals. I work in the IT field, and often get "open box" deals for my friends in high tech toys, but it wouldn't be wise for them to do the same thing, since they don't have the background to evaluate whether the open box is worth the money... or why it is so heavily discounted.


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## Gramp34 (Oct 5, 2006)

It's quite likely you've got the wrong gauges for your sensors.

Some diesel tachs work with a sensor that counts teeth on the flywheel as they go by. Others connect to a 'tach' terminal on the alternator that provides an AC signal proportional to engine speed.

Go to the manufacturer's website and find a datasheet for your tach. It'll have the connection and sensor information. If it's not on-line, call them and ask for tech support.

If your tach only works with alternator signals, and your alternator doesn't have a tach terminal, call an auto electric shop to see if they can add one. Otherwise you either need a new alternator, or a new tach.

Your temp sensor is a switch (e.g., once it gets too hot, the switch closes and the alarm goes off). The gauge needs a sensor that provides a variable signal. Go to an auto parts store and see about getting a coolant temperature sensor. (It might even be cheaper to buy a gauge and sensor together.) If there aren't any other locations for the new sensor, you will have to put it where the old sensor is, and lose the alarm function.

Good luck,

Tim


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## resdog (Mar 29, 2006)

I've learned that Faria guages are usually pretty friendly with every other guage mfg' sensors _except_ VDO and some older Teledyne guages. You have to match your sensors to the particular guages you are using.


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## Northeaster (Jan 13, 2007)

Thanks for the replies!!
Gramp34 - Very helpfull description.
Re: tach - Went on Faria instruments web site, and they describe the 3 types of tachs (alternator type, switching diesel/ mechanical take-off type, and magnetic pickup tach) My Yanmar manual shows my sensor (and OEM tach, if I had one), being magnetic pickup type. Faria's websire says to connect one lead form sensor to tach signal post and the other to ground post on the tach (as well as connecting power /ground). They say to set the switch to the number of gear teeth (which shows 97 in the manual) and do fine tuning with on the back of the tach. I will try calling them tomorrow, as my tach has label instructions on it for using with both a alternator sensor, and mechanical sensor, but nothing there for magnetic pickup (I don't know what switch to set the same as the 97 teeth - maybe this model only does the other two types??)

RE: temp gauge - As my Yanmar book shows temp sensor working as a contact that closes at a certain temp, i would like to add a graduated sensor, to work with my gauge.I do not want to replace the contact/alarm sensor for a gauge sensor only, as the alarm is a nice backup - won't be watching the gauge all of the time. The Yanmar book show the temp sensor having a PT 3/8 size, so I am wondering if I could get something that would tee ofof the one location, to connect the old sensor, and a new one - from an auto parts store. 
Does anyone have both a temp gauge and lamp/alarm on a 2GM engine, as I would like to know where the gauge sensor connects / is located??

On another issue, only one of my decompression levers seems to work - has anyone ever had one sieze - or is there a trick to getting the back one to flip up??

Any input would be appreciated!!


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## Northeaster (Jan 13, 2007)

Re: tach: found out , on Faria instruments websit, that my model tach isn't the right model for magnetic pickup type senders - will only do alternator or mechanical types. Will have to get the proper one!

Re: temp gauge: picked up a PT 3/8" tee and a temp sender/gauge kit. Will try that out in the next day or two.


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## Gramp34 (Oct 5, 2006)

Northeaster said:


> Thanks for the replies!!
> The Yanmar book show the temp sensor having a PT 3/8 size, so I am wondering if I could get something that would tee ofof the one location, to connect the old sensor, and a new one - from an auto parts store.


The trouble with the tee idea is that you want the sensors in the coolant flow so they'll see what temp the circulating coolant is. The coolant in the tee plumbing will be stagnant, so will be slower to react to temperature changes and may not get as hot.

Have a look around to see if there are any pipe plugs covering openings in the coolant loop. If so you can remove the plug and try putting the new sensor in that location.

Cheers,

Tim


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## Northeaster (Jan 13, 2007)

Tim - good advice - hadn't thought of the lack of water flow.

Another problem with the tee connector, or even finding a spare plug in the coolant system - From what I read from the Teleflex instrument website - Yanmar used a PT 3/" 19 (thread) ffitting for their sensors, and the common auto shop tee connectors, and water temp sensors ate NPT 3/8" 18 (thread). Talked to a couple of plumbing shops, who had never heard of the 19 thread. Does anyone have any info on this? Is it possible to get fittings and sensors that are 3/8" 19 ??? Or was a Yanmar specific thing?

Teleflex says you can re-tap to 3/8 18, but would that be worth the risk. What type of metal or cast iron, is the thermostat housing made of (ie how soft is it) and would it be fairly easy, or hard to re-tap?


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## Gramp34 (Oct 5, 2006)

Re-tapping the pipe thread is easy. Pipe threads are tapered, so the tap itself will pull itself in and cut new metal. Cooling systems don't operate under much pressure, so you don't need huge thread strength. Make sure to use either teflon tape or a pipe thread sealant compound.

Hopefully the hole is in the thermostat housing so you can take if off, tap it and clean any cuttings out before you put it back on. If not, a trick is to pack the tap with grease, cut some thread then wipe the grease/cuttings off the tap and keep repeating until the thread is cut deep enough. The grease will catch the cuttings and keep them out of the block. (It might be worthwhile to change the coolant after you're done in any event.)

If the end of the tap hits something before the threads are cut, grind the end off the tap.

Good luck,

Tim


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## Northeaster (Jan 13, 2007)

The sensor does go in the thermostat housing, so I can take it off to tap it. 
Thanks for the input!


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