1989 XR4 150 black max sensor question sn OB263330

[mark abby]

i'm replacing my temperature sender. removed it and it was pretty much rotted.

when I look at XR4 wiring diagrams I see a couple of sensors related to the engine temp:

1. a mercury switch on the port side of the engine
2. a water temperature switch on the starboard side
3. a temperature gauge sender (somewhere else?)

I removed the one on the starboard side and it's the exact same thing as the book showing the temp gauge sender and looks nothing like the one in the manuals I have. Are they one in the same?

also, what is the purpose of the mercury switch? is that temperature related? or, just a safety feature? when I looked for my parts, they show the mercury switch as a temperature sensor. Is it or is it not???

ARGH!! can some one set me straight on this? any help would be appreciated.

 

[mark abby]

ok, so after playing around, I removed the alleged "mercury switch" and I discovered it is related to the temp gauge, when I grounded the TAN wire the gauge went to full hot. so, obviously this is not the "mercury switch" like the book shows.

so, i'll try to find that part number and order a new one of those.

doesn't mercury have a repair manual dedicated just to the XR4 instead of generic service manuals that cover several engines? apparently the XR4 must be unique and unlike other engines.