Mainship 34 wiring

On my Yanmar 370 engin there is a small box, about the size of a pack of cigarettes, with 7 wires all entering on the same end of the box. It is hanging by these wires near the raw water pump and the heat exchanger. These wires have gotten wet and are corroded. Can anyone tell me what this box is or does? This may be preventing me from starting the engin.

Greetings,
Welcome aboard. Sounds like a PFM box to me.

RT Firefly said:

Greetings,
Welcome aboard. Sounds like a PFM box to me.

Click to expand...

I'm a Newbe so what is a PFM?

Lloyd

Which model Mainship 34, the 34T or the Pilot 34? Which year? Is your Yanmar maybe one of the new electronically controlled engines?

I owned a 2006 34T years ago and currently own a 2003 P34, both with Yanmar 370s and I am quite sure that neither have/had the box you describe. I sounds like something added on for the newer electronic engine but i can't believe that Yanmar would just let a box dangle by its wires. So maybe it is a boat builder added device but I can't imagine what.

On further thought, since it is right below the alternator could the PO have added a high output alternator and this box is an external regulator like a Balmar? Do the wires run up to the alternator?

Finally, why did the wires get wet? Your raw water pump seal may be leaking or maybe a hose clamp needs tightening.

David

Greetings,
Mr. VS. My humblest apologies. Yes, you are a Newbe and I should have been more sensitive. PFM box? The wires go in and the wires come out. What happens inside is Pure "Freakin'" Magic. In other words, I have no idea. Again, apologies...

Did you try to follow the wires to find out from where them come and where they are going?

L.

The small box turns out to be a glow plug controller. Found a new one on eBay but could not find a matching connector so I ordered the entire harness. In the meantime I crimped spade connectors on the wires and plugged them in. Still no luck in getting power to the starter system. With help we found that there were two splices down in the bilge that were corroded. Replaced them and everything is now working. Thanks for the feedback.

Glow plug controller??? The Yanmar 370 hp 6LY-STP doesn't have glow plugs. Maybe you mean the air preheater. But Yanmar certainly didn't build that engine with the controller hanging free by its wires.

Maybe some boat builder or previous owner?

David

Now you have me wondering...will have to look at my 6LYA-STP.
Seems odd the pre heat controller would be port side near water pump when heaters are on Stbd????