Engine gauges

[KWKloeber]

Unless me brain is fried (could be the way the day has gone). The temp sender if 1/4" npt, the hi temp switch is 1/8" npt 

Ken

[KWKloeber]

Paul
Somewhere in prior post I said to verify the Senders by checking them with a known good ground.  You can do that only by knowing you have a good ground.  If in question, you wasted your time. 
Either ground to the bty negative post or verify you have a good ground somewhere.

A Voltage check between bty pos and the ground you're verifying, or check resistance between the battery neg and the ground you're checking. 

The first thing to do if ANYone is having ANY electrical problem, is check, and recheck, and clean connections.   DC current depends on both negatives and positives equally, not just positive connections!

Cheers.

[britinusa]

Good point Ron.

I'll call CD to verify.

Paul

[KWKloeber]

Good point Ron.

I'll call CD to verify.

Paul

Paul

It's VERY simple   
Temp sender has a post terminal and is 1/4" npt thread (front of the Tstst cap).
Temp switch has a button (slide on) (i.e., takes a "Packard 56 terminal") and is 1/8" npt thread (same as pet cock on the top of the Tstat housing)

You cannot confuse the two.

Ken

[Ron Hill]

Ken : Kubota does have a 1/4" temp sender and a 1/4" temp switch - believe me. 
Whether CD has - I don't know?

A thought

[britinusa]

Good point Ron.

I'll call CD to verify.

Paul

Paul

It's VERY simple   
Temp sender has a post terminal and is 1/4" npt thread (front of the Tstst cap).
Temp switch has a button (slide on) (i.e., takes a "Packard 56 terminal") and is 1/8" npt thread (same as pet cock on the top of the Tstat housing)

You cannot confuse the two.

Ken

Ken, agreed, the Temp sender I installed has a threaded stud for the connection to the ring terminal on the wire from the gauge.
The Temp switch has a slide on clip. And the thread on the switch is much smaller than the Temp sender.

Paul

[KWKloeber]

Ken : Kubota does have a 1/4" temp sender and a 1/4" temp switch - believe me. 
Whether CD has - I don't know?

A thought

Ron what engine is the 1/4" temp switch for -- I'll look up the part number -  need a 1/4" switch.

Ken

[britinusa]

I guess I could clip a couple of wire extensions to the temp sender and immerse it in a pan of boiling water.

Paul

[KWKloeber]

I guess I could clip a couple of wire extensions to the temp sender and immerse it in a pan of boiling water.

Paul

yeah only the tip needs to be water, so leave the terminal out and clip a wire/vice grip on the hex to hold it.

Just check resistance between the block or sender in place, to the batt neg.

Batty negative is clean and on the starter bolt?
TStat housing was cleaned, 2 bolt threads cleaned, and reassembled with copper anti-seize and a biting lockwasher under the bolt head??
I think the lower part of the housing is bolted on -- could be corrosion there also.

Ken

[KWKloeber]

Shorted the new sensors to the body of the sensor housing and the temp gauge read full right, and the temp alarm sounded (pretty weak!) and the light flashed.

I shorted the temperature sensor housing to the arm of the alternator support.  Still no temp reading.

Paul

Paul

Since you shorted the terminal to the housing -- and the alarm worked (temp switch wire) and the gauge went high (temp sender wire) it seems that you have a good engine ground.  Maybe not prefect, but at least good.   I'd check the resistance of the gauge sender at the temps on the troubleshooting guide.  You can use a heat gun also to bring the temp up.   Also check the temp switch to see if it closes when temp goes up, as there is no telltale for that - (unlike the oil switch/alarm) you never know whether it's functioning until the engine overheats and she alarms (or not!).

Ken

[britinusa]

Last night I checked the Connection between the engine and the main battery -ve.

Connected wire from Main Battery -ve to DMM, Connected DMM to Engine block. Resistance = 0.4 ohms

Paul

[Roland Gendreau]

Are you sure the temperature sender is correct?  The gauge requires a sender that provides 240-33 ohms for the gauge to go full scale.

Also, are you sure your engine thermostat is ok and that the engine temperature is not in fact running low?

[KWKloeber]

Last night I checked the Connection between the engine and the main battery -ve.

Connected wire from Main Battery -ve to DMM, Connected DMM to Engine block. Resistance = 0.4 ohms

Paul

Paul,

0.4 - obviously your engine ground is good enough for the sender to work (very low current.)

What temp are you reading cold and 'hot'?  Are you running her under load or at the dock?
Was the ambient resistance 74 ohms or 740 (about normal.)

Ground ruled out, it points to a gauge or a sender problem.
Do you have the OEM gauge, or PO did an aftermarket auto gauge?

Not having hands-on/eyes-on, it's hard to troubleshoot, but my next step might be to pick up an assortment of resistors at Radio Shack and check the gauge according to the gauge/resistance specs that I mentioned earlier that are on the Wiki site -- 75F (700 ohms), 120F (240 ohms), 212F (55 ohms), 240F (33 ohms) . Radio Shack has a set of mini-alligator cables that makes it easier for clipping resistors and testing. That might be a little easier than checking the sender?  Then if gauge is ok, go the sender resistance in hot water.  BUT remember everything has a +/= to it - gauge/sender up to 20%, resistors, 5% maybe 10%, your meter, thermometer for water temp maybe 10%?  So add it all up and temp gauges are very approximate anyway.

Did you remove the cap and verify that there's a thermostat in installed?

Ken

[britinusa]

After all this it would ironic if the engine was actually at minimum temperature.

I'll go down to the boat this evening.
Check the coolant temperature
Flash up the engine and let it run 10mins
Check the coolant again.

I can make a variable resistor to test the guage (the old split pencil routine)

Will try that too.

Thanks guys.

Paul

[KWKloeber]

Realize that a diesel won't get to normal operating temp unless under load.  Before I changed the WH setup and moved my hoses up to the thermostat bypass loop, I'd run her for an hour at the dock before I got hot water. (OEM the WH was in series with the HX).   With the setup after our C30  engines, you start making hot water immediately - before the Tstat opens.