Bill & Judy Rouse <yahoogroups@...>
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The original sensor was 2 wire as well as the new one.
On Wed, Feb 11, 2015 at 9:24 AM, Kent Robertson karkauai@...
Yes, the electrical schematics for the Yanmar show the sensors grounded where they screw into the block, and they indeed have only one wire.
Was your old sensor also a two wire isolated one? I guess your gauges/idiot lights continued to work properly with the new sensor? The mechanic at my yard says that if you change sensors, you often have to change gauges, too.
I'll have a look at the part you cite and see what I can find out. Wish I could get an answer from Yanmar that makes sense.
When I was in Puerto La Cruz, Venezuela about 7 or 8 years ago, I bought a new oil pressure sensor from the Yanmar distributor there. It had two wire terminal and I believe it was Yanmar part number 119773-91520.
I am thinking that all Yanmar replacement sensors/senders are two terminal types which probably are isolated ground.
I cannot find where Yanmar makes 2 different sensors/senders...only one, and I am 99% sure it is 2 wire. And, I believe that since Yanmar does understand isolated grounding, these 2 wire sensors are isolated ground.
Did you check your sensors for 1 wire or 2 wires?
I hope this helps, more than it confuses.
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On Wed, Feb 11, 2015 at 6:21 AM, Kent Robertson karkauai@... [amelyachtowners] <amelyachtowners@...> wrote:
Thank you Eric. I thought that had to be the case, but the guru at Mastry (the U.S. Yanmar contact) has told my electrical engineer that no isolated sensors are available. They must be made by someone other than Yanmar.
If anyone knows where to get them, please let me know.
The Yanmar and Onan have a separate Negative from the rest of the boat as they have a separate battery. I have not looked at the 12 alternator but the negative lead from the start battery is only connected to my boat when the engine starts. Yes, isolated ground senders are available as I have them on my engine, if you have separate oil and temp gauges, they are also available with an isolated ground.
Sorry I am not on the boat to send you photos.
Kimberlite SM 376
I haven't gotten an answer from Yanmar. Have been told to take the boat to Wards Electric in Ft Lauderdale. Do you know if it's possible to get isolated sensors, starter, and alternator for Yanmar engines? Olivier says I can leave it as is and add a galvanic isolator. I will also add a hull pote
ntial meter so I can monitor for leaks.
The sensors for the Yamaha should all be isolated ground sensors with 2 wires on each. If your sensors have one wire they use the block as a ground ( battery -) and are the wrong sensors. Amel did a lot to isolate the engine from the DC negative.
Kimberlite SM 376
I'm still not sure how to connect the electrical systems of my non-isolated Yanmar 4JH4HTE to avoid electrolytic issues in the future. The consensus here seems to be that the bonding system should have no connections to the 220, 24, or 12V grounds. The starter, 12V alternator, and sensors (temp, oil pressure, etc) are grounded to the engine block. I'm still checking with Yanmar to see if isolated starter,
alternator, and sensors are available, but I don't think they are...so I can't isolate the engine block (and thus the Cdrive) from the bonding system without having a connection to the 12V battery negative post.
Should I leave the engine connected to both the bonding system and the 12V negative pole (thus leaving the transmission and Cdrive connected through the engine)?
I've looked for a bonding wire to the generator, and don't see one. I remember Eric's description of the genset as having a "floating ground" (or something like that, can't find it now). Does that mean that the generator is not connected to the bonding system? If so, then the small zinc in the raw water system is all that is protecting the generator from galvanic (or electrolytic) damage?