Hunter 410 Temp Reading High

[sailing gal]

My 4JH3E temp is reading high. The reading on the gauge has always been high really, but earlier in the year while in Bahamas it pegged high starting a "fire" drill. But the temp on the housing measured about 160F. It has been around 50-100 hours since and the temp never measures hot directly.

I replaced both the sender and gauge. Have tried 2 sensors now including a genuine Yanmar. It still reads 200+ with the housing it is screwed into reading 156-160F.

The gauge tests good. If I ground the wire ro the sender the gauge pegs high. I ran a long jumper wire from the gauge to the sender and it reads the same, so doesn't appear to be an engine harness wire problem.

Ideas?

 

[Ralph Johnstone]

Yanmar water temperature sensors are most often a thermistor with the resistance inversely proportional to the temperature or simply put : as the temp. goes up, the resistance goes down.

It sounds like you've got either a partial ground in the sensing wiring or a high resistance (corrosion) in the gauge ground.

 

[JoeWhite]

What happens if you wire the gauge near the engine with new wiring for testing only

 

[sailing gal]

I ran a brand new wire from the panel to the engine, nothing changed

 

[sailing gal]

Maybe the gauge range is, and has been, wrong. What range is one your H410? (only those with a H410 should reply)

 

[Ralph Johnstone]

Maybe the gauge range is, and has been, wrong.

The reading on the gauge has always been high really, but earlier in the year while in Bahamas it pegged high

Something changed during "earlier in the year". This eliminates the gauge as being the wrong range.

I ran a brand new wire from the panel to the engine, nothing changed

1. You have eliminated the possibility of a ground fault leading to the thermistor.
2. If you had a poor ground connection at the sensor, you would have a low temperature read out at the gauge due to high resistance.
3. Get to work on the resistance of the gauge ground (-) connection.

 

[sailing gal]

nothing wrong with the sensor ground to the engine and negative system

 

[jssailem]

I replaced both the sender and gauge.

Maybe the gauge range is, and has been, wrong

Temp Gauges have a temp range. They need a sensor that matches the gauge range.
I just bought a new sensor for my VDO gauge. The range of the sensor needed to be 12V, 250º, with an ohm reading of 30-240.

The VDO install manual says it very clearly. What is good for a VDO gauge applies to the rest of the world... Even Hunter boats.

Also when installing the sensor do not use teflon tape. A dab of pipe dope is ok, but tape can block the ground the sensor needs (metal on metal) of the engine block to properly work.

 

[shemandr]

Maybe the engine is running hot - that's what the temp gauge is telling you. I mean why blame the gauge? If the housing isn't hot by measure of however you measured it - I suspect it depends on where it's measured - then your temp sensor is your de facto temperature gauge. Choose which one you want to believe.

 

[sailing gal]

Temp Gauges have a temp range. They need a sensor that matches the gauge range.
I just bought a new sensor for my VDO gauge. The range of the sensor needed to be 12V, 250º, with an ohm reading of 30-240.

The VDO install manual says it very clearly. What is good for a VDO gauge applies to the rest of the world... Even Hunter boats.


Also when installing the sensor do not use teflon tape. A dab of pipe dope is ok, but tape can block the ground the sensor needs (metal on metal) of the engine block to properly work.

 

[sailing gal]

Problem has to be a mismatch between the Yanmar OEM senor and the no name gauge. I would think a Yanmar gauge would match as I installed a genuine Yanmar sensor and it doesn't matter that it reads in C to me. But the cost difference is just hard to accept.

 

[jssailem]

cost difference is just hard to accept.

Check the gauge specs. Then get a sensor the matches.

 

[sailing gal]

Problem has to be a mismatch between the Yanmar OEM senor and the no name gauge. I would think a Yanmar gauge would match as I installed a genuine Yanmar sensor and it doesn't matter that it reads in C to me. But the cost difference is just hard to accept.

So replaced with an Yanmar OEM gauge to go with the OEM sender and it reads correctly now. The Yanmar gauges must have a different ohm range than "vdo" gauges. I bet the boat didn't come from the factory with a Yanmar sender and gauge.

 

[Sailgunner]

I usualy run from 175 to 190. It gets close to 200 if I push it hard and the sea water is warm.

 

[sailing gal]

I usualy run from 175 to 190. It gets close to 200 if I push it hard and the sea water is warm.

Well my new Yanmar sender/gauge combo read about 80C/176F the other day. That is lower than it has ever read in the 12 years I have owned the boat and seem to better match what I learned during all this it should it should be.