Temp gauge mystery ( got to read this one)

[scooter4n]

Ok, so I got newer boat 1990 Chaparrel with I4 3.0L Mercruiser 130HP.
Took it on the water and motor runs good, starts good, temp gauge not working, ok, I take sensor wire and touch the ground, gauge needle maxing out, ok so gauge working.
I get new sensor, plug it in, take it out and gauge not working again.
I think, maybe bad ground to the body, so I run wire to the sensor body, nothing.
I get home, take sensor out, ground with wire, and put it on the glass of boiling water and gauge showing temp.
whats up with that?
1. sensor new and working
2. gauge working
3. ground good
4. i have water poring out of the sensor hole every time i take it out.
5. I run boat for nice 15-30 min at about 3000-3500RPM and nothing, not even move...
Can some one explain this one???

 

[Gary H NC]

Re: Temp gauge mystery ( got to read this one)

Have you tried running new wires to the gauge one at a time.Its got to be a connection problem some where between the engine and the dash..

 

[95yj]

Re: Temp gauge mystery ( got to read this one)

Either that or his cooling system works really good

 

[scooter4n]

Re: Temp gauge mystery ( got to read this one)

Either that or his cooling system works really good

can that be possible to run engine at 100F??? or your kidding

 

[scooter4n]

Re: Temp gauge mystery ( got to read this one)

Have you tried running new wires to the gauge one at a time.Its got to be a connection problem some where between the engine and the dash..

but it works with old wires when I put sensor in the cop of hot water. Gauge is working. temp go up to like 150-160F

 

[Nova II 260]

Re: Temp gauge mystery ( got to read this one)

Check your thermostat. Could be missing or stuck open.

 

[scooter4n]

Re: Temp gauge mystery ( got to read this one)

where is it located???

 

[cheburashka]

Re: Temp gauge mystery ( got to read this one)

You really should have a manual that can tell you things like where the thermostat is. On your engine, it's at the very front and top of the engine, under the housing that holds the hose where the water exits the engine.

You say you grounded the sender to test it. Did you try using that ground wire again when you reassembled everything? The sender mounts into a bolt-on housing which could conceivably be isolated from the ground circuit. Make sure that the sender unit has good ground. You should be able to test it just by grounding the sender with wire while the engine is running.

 

[scooter4n]

Re: Temp gauge mystery ( got to read this one)

You really should have a manual that can tell you things like where the thermostat is. On your engine, it's at the very front and top of the engine, under the housing that holds the hose where the water exits the engine.

You say you grounded the sender to test it. Did you try using that ground wire again when you reassembled everything? The sender mounts into a bolt-on housing which could conceivably be isolated from the ground circuit. Make sure that the sender unit has good ground. You should be able to test it just by grounding the sender with wire while the engine is running.

I did grounded when I was on the water just with the wire, nothing.
I know what your talking about as for location of thermostat.
I bet this is thermostat open or missing, but man keeping all the way down to 100F almost unbelievable.
I'll check that today after work
Thanks all for your time

 

[wire2]

Re: Temp gauge mystery ( got to read this one)

Put your hand on the block, does it feel like 100? or less? (125? is pain threshhold).
If it's hotter than 100, check the sensor wire with a DC voltmeter relative to ground.
If 0, there's a wiring problem at the gauge. Check for 12v and 0 on the + and - terminals of the gauge.

 

[scooter4n]

Re: Temp gauge mystery ( got to read this one)

ha ha, no thermostat, lol
So I got one in, test drive Saturday.

 

[freddyray21]

Re: Temp gauge mystery ( got to read this one)

"I bet this is thermostat open or missing, but man keeping all the way down to 100F almost unbelievable. "

It is bringing in cold water from the lake. New fresh water all the time. Not like in a car where you are recirculating the same water over and over. It will stay cold if there is no thermostat.

 

[scooter4n]

Re: Temp gauge mystery ( got to read this one)

Ok, quick one on the motor question.
Mercruiser 1990, 3.0L
If you stand in front of the motor, in front on the left side some oil/flued pump driven by the belt with reservoir on top.
What is that for and what oil/fluid do I need for it.
Thanks

 

[Gary H NC]

Re: Temp gauge mystery ( got to read this one)

i would bet its the steering pump.What color is the oil in it?

 

[scooter4n]

Re: Temp gauge mystery ( got to read this one)

Red.

 

[scooter4n]

Re: Temp gauge mystery ( got to read this one)

Red

 

[freddyray21]

Re: Temp gauge mystery ( got to read this one)

power steering pump. you need to pick up a manual

 

[Zero Balance]

Re: Temp gauge mystery ( got to read this one)

there are several different types of "sending units. Some are for lights, some mechically operated for gauges. Of the second variety, mech. sending units must also be compatible to the gauge it'self. Are you sure you have the right temp sending unit?

 

[freddyray21]

Re: Temp gauge mystery ( got to read this one)

I think he fixed that issue when he realized their was no thermostat.

 

[blueoval1]

Re: Temp gauge mystery ( got to read this one)

I found if you wrap the sender threads with teflon tape or any other sealer , that the gauge will not work or it does funky things also.
Just in case he still has problem with the temp gauge , might help.