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Coolant circulating?

F

flyingace

Member
1966 Ford 3000 diesel. Is there a way to tell if the coolant is circulating? I've put in a new thermostat, but the gauge still tells me the engine if overheating. I'm not sure I trust the gauge. The top radiator hose is hot when the engine is running, the lower hose is luke warm or even ambient temp. The radiator is in good shape and the water pump is also new. Fan shroud was purchased and installed with the new water pump.

The engine gives me no external signs of overheating, but I'm still concerned that the engine is too hot. I've measured the coolant while the engine was running hot, and it was lower than the 188 degrees required to open the thermostat. But if the coolant isn't circulating, then that temperature won't reflect engine heat at the sensor. Ideas?
 
(quoted from post at 15:23:59 06/17/13) Most likely the gauge, or more specifically, the instrument voltage regulator. Does the fuel gauge read high also? If so, that's it.
Click to expand...

The fuel gauge is inoperative. But what you way about the voltage regulator may hold water. The temp gauge seems to jump around faster than it would seem possible for the engine to heat and cool down. It seems to jump down when the engine RPM goes up. Is there some way to determine if the voltage regulator is bad?

Thanks for the reply.
 
I can't speak for Bern but I think he was referring to the voltage stabilizer not the voltage regulator in the charging system.
Stabilizer is a small rectangular box that is screwed on to the back of the instrument cluster.
Others here are better at electrics than I and could probably tell you how to test it.
 
Yep, I mis-spoke - thanks for catching that. I was talking about the voltage stabilizer on the back of the dash. It looks like a circuit breaker with two wires going to it.

To test: Turn the key on and test both wires one at a time with respect to ground with a meter or test light. Voltage should be stable on one side, and pulsate on and off on the other. If both sides are continuous, that's your problem. Give it at least 30 seconds warm up time though.
 
(quoted from post at 03:48:21 06/18/13) Yep, I mis-spoke - thanks for catching that. I was talking about the voltage stabilizer on the back of the dash. It looks like a circuit breaker with two wires going to it.

To test: Turn the key on and test both wires one at a time with respect to ground with a meter or test light. Voltage should be stable on one side, and pulsate on and off on the other. If both sides are continuous, that's your problem. Give it at least 30 seconds warm up time though.
Click to expand...

I would not trust a voltmeter because a voltmeter will not catch it if the cycle times are fast a voltmeter will throw you a curve ball . A voltmeter could be used to check the ignition side but not the output gauge side.

A test light would show the gauge side pulse (blink on and off)..
It operates more like a circuit breaker it should show a steady pulse if its erratic (on/off) the gauge will be in inaccurate...

If one has a lab scope are a graphing multi-meter it would be top choice... I know you know and you gave great advice my statement was to not let a voltmeter fool ya...

The fuel gauge is a short the voltage regulator breaks on/off depending on the resistance of the fuel sender input. If it does not break the gauge will go up in smoke... The body of the regulator has to be grounded for it to work...
 
The 5 buck multimeters might not catch the pulse but the 400 dollar Flukes will provided you know what to watch for or how to set it's data logger.

Rod
 
(quoted from post at 04:58:07 06/19/13)
(quoted from post at 03:48:21 06/18/13) Yep, I mis-spoke - thanks for catching that. I was talking about the voltage stabilizer on the back of the dash. It looks like a circuit breaker with two wires going to it.

To test: Turn the key on and test both wires one at a time with respect to ground with a meter or test light. Voltage should be stable on one side, and pulsate on and off on the other. If both sides are continuous, that's your problem. Give it at least 30 seconds warm up time though.
Click to expand...

I would not trust a voltmeter because a voltmeter will not catch it if the cycle times are fast a voltmeter will throw you a curve ball . A voltmeter could be used to check the ignition side but not the output gauge side.

A test light would show the gauge side pulse (blink on and off)..
It operates more like a circuit breaker it should show a steady pulse if its erratic (on/off) the gauge will be in inaccurate...

If one has a lab scope are a graphing multi-meter it would be top choice... I know you know and you gave great advice my statement was to not let a voltmeter fool ya...

The fuel gauge is a short the voltage regulator breaks on/off depending on the resistance of the fuel sender input. If it does not break the gauge will go up in smoke... The body of the regulator has to be grounded for it to work...
Click to expand...

ding ding ding. We have a winner! The gauge would fly up to red when I turned the ignition on if the instrument cluster was out of the tractor. When I put the cluster back in, it would stay
down. I grounded the instrument cluster with a grounding wire and drove around (it's almost 90 here). The gauge went to half way and stayed put - even at idle. I think it's fixed

I believe the way it was acting was a result of intermittent (or incomplete) grounding.

Thanks for all the help.
 
(quoted from post at 04:07:57 06/20/13)
(quoted from post at 04:58:07 06/19/13)
(quoted from post at 03:48:21 06/18/13) Yep, I mis-spoke - thanks for catching that. I was talking about the voltage stabilizer on the back of the dash. It looks like a circuit breaker with two wires going to it.

To test: Turn the key on and test both wires one at a time with respect to ground with a meter or test light. Voltage should be stable on one side, and pulsate on and off on the other. If both sides are continuous, that's your problem. Give it at least 30 seconds warm up time though.
Click to expand...

I would not trust a voltmeter because a voltmeter will not catch it if the cycle times are fast a voltmeter will throw you a curve ball . A voltmeter could be used to check the ignition side but not the output gauge side.

A test light would show the gauge side pulse (blink on and off)..
It operates more like a circuit breaker it should show a steady pulse if its erratic (on/off) the gauge will be in inaccurate...

If one has a lab scope are a graphing multi-meter it would be top choice... I know you know and you gave great advice my statement was to not let a voltmeter fool ya...

The fuel gauge is a short the voltage regulator breaks on/off depending on the resistance of the fuel sender input. If it does not break the gauge will go up in smoke... The body of the regulator has to be grounded for it to work...
Click to expand...

ding ding ding. We have a winner! The gauge would fly up to red when I turned the ignition on if the instrument cluster was out of the tractor. When I put the cluster back in, it would stay
down. I grounded the instrument cluster with a grounding wire and drove around (it's almost 90 here). The gauge went to half way and stayed put - even at idle. I think it's fixed

I believe the way it was acting was a result of intermittent (or incomplete) grounding.

Thanks for all the help.
Click to expand...

Actually Bern is the winner (that was a good catch) I did not read your post good enough to catch what he did. It was you lucky day tho that I did include the grounding of the regulator body BTDT got the patch... I know he knew it also.

You can get good advice when you supply good info like you did,, that weeds out the guessers...
 
You should have used a meat thermometer to test the top tank temperature.The thermostat will start to open a bit before it marked temperature.The unit on the gauges will not work right if the fuel gauge is open.The first step in overheat problems is test the top tank temp with a meat thermometer.Has worked for me since the 50s.
 
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