Grease Monkey Garage

[Duce]

6.0 has enough beans to kill a Dana 80

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In 2004 I owed a ford f350 6.0 and could not get rid of it fast enough. More time at dealer than with me.

 

[FergusonTO35]

Here is my daily fix for my 1998 F250, coolant temp gauge has been flaky and today on my way home from work, didn't lift off of the bottom of the gauge, heater blew cold air the whole way home. The coolant reservoir was was full and overflowing a little (due to the thermostat not opening up). Tested the gauge (shorting out the pins on the connector) and the gauge pegged hot. Went to O'Riley's and got one of their AM temp sensors and it didn't work (it fit, but didn't register anything), I wasn't surprised, the reviews weren't that great, but everything else was closed. I thought I would meter out the sensors and see what they say here is what I found:

* O'Riley's states that the manufacture range should be between 27,000 and 31,000 ohms (not sure if that is just the ambient temp range or the hot/cold range)
* The original OEM sensor metered out at 6,000 (cold 70F water) and dropped to around 500 ohms in 212F water.
* The AM sensor metered out at 28,000 (cold) and dropped to about 24,000 ohms in 212F water.

I ended up cleaning the corrosion off of the OEM sensor with a brass brush and scotch bright and reinstalled it and it ended up working. I will use it for now until I can order an OEM replacement.

My question surrounds the resistance readings from the sensors, should it be a specific ohm range these work in or is it more of a percentage of resistance? I am using a Fluke digital multi-meter that is auto sensing.

I'm surprised you were able to find a published Ohm value for the O'Reilly sensor.

 

[hacskaroly]

I'm surprised you were able to find a published Ohm value for the O'Reilly sensor.

The quoted value by O'Reilly was their quoting the "manufacture's information", I am assuming they were quoting Ford or something Ford published. They didn't site their source so I guess it could have been made up - maybe they quoted Google AI...

 

[FergusonTO35]

I would think the replacement sensor should be at least close to the factory Ohm spec, otherwise the ECM couldn't work with it.

 

[hacskaroly]

I would think the replacement sensor should be at least close to the factory Ohm spec, otherwise the ECM couldn't work with it.

That is what I thought too, but perplexing that the OEM is 80% working (it seemed to quit as I was driving home, needle settled to the bottom, but resurrected as I had to drive up the hill to Tractor Supply and worked for the rest of the day) and the AM didn't work at all.

 

[Steve]

Here is my daily fix for my 1998 F250, coolant temp gauge has been flaky and today on my way home from work, didn't lift off of the bottom of the gauge, heater blew cold air the whole way home. The coolant reservoir was was full and overflowing a little (due to the thermostat not opening up). Tested the gauge (shorting out the pins on the connector) and the gauge pegged hot. Went to O'Riley's and got one of their AM temp sensors and it didn't work (it fit, but didn't register anything), I wasn't surprised, the reviews weren't that great, but everything else was closed. I thought I would meter out the sensors and see what they say here is what I found:

* O'Riley's states that the manufacture range should be between 27,000 and 31,000 ohms (not sure if that is just the ambient temp range or the hot/cold range)
* The original OEM sensor metered out at 6,000 (cold 70F water) and dropped to around 500 ohms in 212F water.
* The AM sensor metered out at 28,000 (cold) and dropped to about 24,000 ohms in 212F water.

I ended up cleaning the corrosion off of the OEM sensor with a brass brush and scotch bright and reinstalled it and it ended up working. I will use it for now until I can order an OEM replacement.

My question surrounds the resistance readings from the sensors, should it be a specific ohm range these work in or is it more of a percentage of resistance? I am using a Fluke digital multi-meter that is auto sensing.

Sounds like you're temp sensor is working ok, it's your thermostat that is stuck open not allowing the coolant temp to rise. That would be why you have no heat too.

 

[hacskaroly]

Sounds like you're temp sensor is working ok, it's your thermostat that is stuck open not allowing the coolant temp to rise. That would be why you have no heat too.

I guess that is a possibility, I replaced it less than a 1,000 miles ago, but I may have to revisit possibly replacing that again.

Today when I drove to work, everything was working fine (needle movement and heat). When I drove home, about a mile from the house, the needle on the gauge started going down and the heater air started cooling) and when I parked at the house with it running, the needle settled at the bottom. I left the house and about a mile later, the needle on the gauge started creeping back up to it's normal warm position and it worked fine for the rest of the day.

 

[Steve]

I guess that is a possibility, I replaced it less than a 1,000 miles ago, but I may have to revisit possibly replacing that again.

Today when I drove to work, everything was working fine (needle movement and heat). When I drove home, about a mile from the house, the needle on the gauge started going down and the heater air started cooling) and when I parked at the house with it running, the needle settled at the bottom. I left the house and about a mile later, the needle on the gauge started creeping back up to it's normal warm position and it worked fine for the rest of the day.

Yup, you have a bad new thermostat. Get a motorcraft thermostat and let us know how it goes.