Engine Temp gauge not working.

[spj]

I changed the oil in my engine (Merc 305 Inboard)saturday, and now my engine temp gauge does not work. I do not think they are related other then timing.

I did check to make sure I did not break the wire on the sending unit, as I have to lay on top of the motor to get to the oil filter.

How do I go about testing the gauge and the sender to see where the problem is?

scott

 

[pdecat]

hook the wire to ground note the reading then unhook and leave it open. The meter should move min to max

 

[montana]

From the Mechanical How-To section:

http://www.downloadingfiles.co.uk/teleflexfiles/gauges/Inboards,%20I-O's.pdf

 

[Sandy]

Here's Faria's gauge trouuble-shooting version which may be a little more helpful that Teleflex's latest gauge diagnostic.

http://faria-instruments.com/site_manuals/IS0085E.pdf (resistence values)
http://faria-instruments.com/site_manuals/IS0100_ApxVII.pdf ( diagnostic flow chart)
http://faria-instruments.com/site_manuals/IS0100_MiscGauges.pdf ( the good stuff)

Even if the wires and connections look OK, the timing as you say is a little too coincidental. The sender may be cracked or wires stretched and broken internally or pulled slightly loose inside a ring or spde connector. Make sure you are looking at the temp gauge sender rather than the temp gauge alarm switch.

 

[spj]

Montana & Sandy

Thank you both very much. Those documents were exactly are exactly what I need to trouble shoot the problem. It will be the weekend before I get back, but I will let you know what I find.

Scott

 

[Tanqueray]

Just disconnect the wire at the sender....turn on the key and ground the wire to the engine anywhere. It should peg the gauge. If it does...the wiring is okay. If it doesn't...look for the broken wire.