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Old 10-21-2020, 04:52 PM   #1
billybronco1
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Default Which Oil Sending Unit Should I Use?

I was looking online and there is a 50 psi and an 80 psl. Current oem gauge reads 25 psi at best, seems low. Owner said other original engine was the same, as this engine was replaced about 3000 miles ago. He has been driving it for 6 years without any issues. I'm not sure if they moved the sending unit from the original engine to the new engine, but if they did maybe its bad, or can the gauge be bad? What should the normal psi be at idle and them higher rpm?
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Old 10-21-2020, 05:05 PM   #2
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Default Re: Which Oil Sending Unit Should I Use?

If you have the 21 stud engine, you must have the 50# sending unit.
The correct sending unit will have NO markings on the base. Later service parts that are 50# units, will have "50" stamped in to the base.

At idle, if you get any reading on the dash gauge, you're okay. A fully wared up engine going down the road, maybe 30#, maybe. Most likely nearer 20#.

Dash gauges are notoriously inaccurate. Many guys install a mechanical gauge for more confidence in the readings.
You have a nice looking car... if you install a mechanical gauge I'd suggest you either keep it under the hood or hide it in the glove box.
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Old 10-21-2020, 05:08 PM   #3
billybronco1
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Default Re: Which Oil Sending Unit Should I Use?

Thanks for that info, that makes me feel better. I see there is a plug over the current gauge, is this a good spot to add a mechanical gauge?
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Old 10-21-2020, 05:13 PM   #4
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Default Re: Which Oil Sending Unit Should I Use?

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Thanks for that info, that makes me feel better. I see there is a plug over the current gauge, is this a good spot to add a mechanical gauge?
If you mean about an inch away from the stock sending unit, then yes, that's a perfect spot.
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Old 10-21-2020, 05:24 PM   #5
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Default Re: Which Oil Sending Unit Should I Use?

Sorry, I thought I posted a pic of what I had, I always forget that part.
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File Type: jpg Oil sending unit.jpg (33.3 KB, 62 views)
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Old 10-21-2020, 06:07 PM   #6
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Default Re: Which Oil Sending Unit Should I Use?

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I put a direct reading gauge on my 40 and the oil pressure was double of what the gauge read with the original sender. So I installed the original sender and know that the gauge reads half of the actual oil pressure.
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Old 10-21-2020, 06:16 PM   #7
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Default Re: Which Oil Sending Unit Should I Use?

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Sorry, I thought I posted a pic of what I had, I always forget that part.
Yes sir... that's the optimum place...
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Old 10-21-2020, 06:35 PM   #8
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Default Re: Which Oil Sending Unit Should I Use?

I would like to put in a more accurate temp gauge too, do you know if there is a 6 volt gauge set up available? Where would you mount the sending unit?
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Old 10-21-2020, 07:59 PM   #9
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Default Re: Which Oil Sending Unit Should I Use?

Or just use a mechanical gauge.
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Old 10-21-2020, 08:30 PM   #10
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Default Re: Which Oil Sending Unit Should I Use?

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I would like to put in a more accurate temp gauge too, do you know if there is a 6 volt gauge set up available? Where would you mount the sending unit?
Just do a test of your existing gauge to determine what actual water temperature corresponds to the markings on your gauge. Use a heat gun on the radiator right under where the passenger side top hose enters the top tank. Normal calibration would be 160 at the center mark, 180 at the 3/4 mark and 200 at the top mark. Mine reads about 10 degrees cooler than that, but I know that. If my gauge hits the top mark, it will be blowing steam.
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Old 10-21-2020, 08:41 PM   #11
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Default Re: Which Oil Sending Unit Should I Use?

The last few days I have been letting the car run at idle for about 45 minutes trying to seal a leaky head gasket with sealer. The car is not registered so I can't drive it. First two days the gauge sat at 3/4 once hot, today it was all the way to the top but it was not steaming. Hopefully it will run cooler when driving. BTW the leak is slowing down.
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Old 10-21-2020, 10:02 PM   #12
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Default Re: Which Oil Sending Unit Should I Use?

It is very common for these engine to run hot at idle.
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