Installing oil temp gauge

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I am installing an oil temperature gauge in my 2008 Dodge Ram diesel and want to use the 1/8-NPT port on the top of the oil filter base.
Has anyone used this port for this purpose before? Is there any issue with the sensor blocking off an oil passage? The sensor I bought can be trimmed for length by ~1/4".
 

A_Harman

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I have checked some Dodge diesel forums, and found a couple of guys who have put temp sensors in there. But never any follow up messages about the results.
 
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How does the sensor wire come out? Doesn't this adapter go between the oil filter base and the housing?

I'm curious because I have also been wanting to add oil temp gauge to one of my cars but have a hard time to figure out. Even in couple of very popular car websites no one has done it which kind of surprised me!
 

A_Harman

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No. The filter base on the Cummins has an 1/8NPT port on the top with a plug in it. The sensor that came with the oil temp gauge has 1/8NPT threads, so I just took out the plug, and screwed in the sensor. That part is easy. In the gauge instructions, it said the end of the sensor can be trimmed in length, which I had never heard of before. I pulled out my Dremel tool with the cutoff wheel, and cut about 1/4" off the sensor, in order to minimize the possibility that it could be restricting a flow passage. I don't know the internal details of the filter base and am playing it safe. I started the truck up after installing the sensor, and oil pressure came up and stabilized normally, so all seems OK so far. Then running the wires, finding power and ground connections, and mounting the gauge are next.
 

A_Harman

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The filter base is after the oil cooler, so I will be reading the oil temperature that goes to the bearings. Also, the oil supply hose to the turbo is on the top of the filter base.
 

A_Harman

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OK. Got everything hooked up, and the gauge mounted. Did a 15 minute idle period, and the oil temperature bumped off of 140F when the coolant temperature got over 140F. The oil temp gauge range is 140-300F. It's a Holley stepper motor gauge.
 

A_Harman

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So far, the gage has been working fine. I have driven the truck for a week, both loaded and unloaded, and it's been OK. Oil pressure seems normal. The highest temperature I have seen so far is 226F when I was towing on a 90-degree day. Running unloaded, the oil temp temp stays fairly close to coolant temp, 208F seems to be a normal reading. Considering the gage is sensing after the oil cooler, I imagine that the temperature in the oil pan would be about 250F. This doesn't seem to be high enough to cause oxidation that my UOA's have been showing on RT6.
 
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2,034
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So far, the gage has been working fine. I have driven the truck for a week, both loaded and unloaded, and it's been OK. Oil pressure seems normal. The highest temperature I have seen so far is 226F when I was towing on a 90-degree day. Running unloaded, the oil temp temp stays fairly close to coolant temp, 208F seems to be a normal reading. Considering the gage is sensing after the oil cooler, I imagine that the temperature in the oil pan would be about 250F. This doesn't seem to be high enough to cause oxidation that my UOA's have been showing on RT6.

Interesting. So the pan temp would be higher because it hasn't been cooled off by the cooler yet. is that true?

When I was looking at different ways to add an oil temp gauge to my Tundra, most (including some good Toyota mechanics) suggested adding a drain plug sensor which is very easy to add and wire but everyone was also saying that the pan temperature will be lower because it is in the pan ....

I never thought too much about it and kind of agreed since the pan gets cooled off by some air flow as well. Sounds like that would have been a wrong assumption.

btw, what is your opinion about drain plugs with temp sensor? I was concerned with the hollowed out drain plugs and potential weakness and disaster. That's why I also don't like magnetic drain plugs. I used a magnetic plug only once and it didn't catch anything so I changed back to the oem plug.
 

A_Harman

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Messages
8,032
Location
Michigan
Interesting. So the pan temp would be higher because it hasn't been cooled off by the cooler yet. is that true?

When I was looking at different ways to add an oil temp gauge to my Tundra, most (including some good Toyota mechanics) suggested adding a drain plug sensor which is very easy to add and wire but everyone was also saying that the pan temperature will be lower because it is in the pan ....

I never thought too much about it and kind of agreed since the pan gets cooled off by some air flow as well. Sounds like that would have been a wrong assumption.

btw, what is your opinion about drain plugs with temp sensor? I was concerned with the hollowed out drain plugs and potential weakness and disaster. That's why I also don't like magnetic drain plugs. I used a magnetic plug only once and it didn't catch anything so I changed back to the oem plug.
Yes. After running through the bearings, the piston oil cooling galleries, and being thrashed around the pan by the crank, the oil will be the hottest it can be before being picked up by the pump and sent to the cooler. Air cooling of the oil pan will help, but the major amount of cooling is done by the cooler. In the Cummins engine, the oil cooler is in a separate compartment in the water jacket, and the oil system rejects its heat through the engine radiator.

I would be worried about the vulnerability of the wires coming off of a drain plug temperature sensor. My current thinking is to have a thermocouple installed on the dipstick. I have a fancy voltmeter that has a thermocouple sensing function. I just bought it for chasing down the stray current that is flattening my batteries.
 
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