Where is the Tachometer sensor on a Yanmar 4JH3e?

[MarkJ]

Hi Folks

I am looking for the tachometre sensor on my Yanmar engine.

Gords pic in this post doesnt help because it doesnt say what the big blob is: http://www.cruisersforum.com/forums/f14/smart-regulator-for-yanmar-alternator-7620.html

Can someone do a quick photo and show me please?
Its not in the book or on the friggin internet

My problem is my tacho suddenly stopped working! It wouldnt come on this afternnon when we started it up to charge the batts.

The other instruments work and the light comes on in the tacho.

I would like to start by seeing if the sensor is loose.

Mark

[cal40john]

The big blob is the bell housing that covers the flywheel. The off center hole you see is where the starter motor bolts on, but Gord also says that this picture only holds for the GM series of engine. The rest of the Yanmar line, he says the alternator is the source of the tach pulse.

I have a GM series engine, and the picture and my engine match. What I don't know for sure is if your J series engine uses the alternator or not.

John

[MarkJ]

Thanks John.

I changed the V belt 2 days ago and had a bit of a problem getting the new one on so I bet I have stuffed it up!

[cal40john]

After thinking about the picture for awhile, I realized that my starter is on the other side of the engine, but the mirror image of the picture would be pretty close to what I have. Looking back at the picture I see that ring tooth numbers are given for GM, JH, LH, LY, and CX series, so I assume those engines also have a flywheel pickup and that the housing picture is from one of the other series listed.

Still doesn't help you with your series though.

John

[GordMay]

Trace the wires back from the tach to the engine. The Yanmar wiring harness uses the Blue/Red and Orange wires for the Tachometer sender, and the Red/Black (+) and Black (-) for Instrument Power.

[Hud3]

Mark,

Here's a link to the "Electrical" chapter from the Yanmar service manual. The "Tachometer" page shows the pickup location on the flywheel housing.

[MarkJ]

Thanks for the link to the PDF, Hud. I still can't find it.

Is the thing here circled the tacho sensor?

[Hud3]

Mark,

I have the same engine as you (4JH3BE), but I've never had occasion to look for the tach sensor. Comparing your photo to the drawing in the manual, I'd say "Yes". To be sure, trace the wires back to the instrument panel.

Good luck!

[never monday]

Mark,
that's it

[MarkJ]

I've fixed it!!!!!!!!!

Thanks everyone and Never Monday

I have been stuffing around with the alternator changing the V Belt and also with the Oil Cooler (at the back of the engine) so when the Tachometer failed the next day it was more likely to be the wiring into the engine (the Tachometer sensor) than the wiring into the instrument.

So I was able to lever the 2 wires off, sand the terminals and scratch the inside of the plugs, squirt some CR2, pinch the plugs a bit tighter and put them back on.

Hey, Presto! It works

So for anyone googleing this problem I hope this comes up

The photo in my earlier post is, looking from the rear. The Tachometre Sensor is in the upper left corner of the engine at the back under a very short hose (that connects the raw water to the oil cooler).

I think the corrosion there was from a leaky oil cooler hose which I needed to replace the hose clamp a few months ago.

Note: The colour of the wires is not a help because near the engine they have all been painted grey and come out of the plastic bundle grey.




Mark