Oil gauge issue

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luminous05

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Howdy, I recently noticed my truck giving me seemingly strange high oil pressure readings which didn’t correspond with the actual pressure, after replacing the gauge, and the sending unit (which was accidentally purchased for an 85 350 instead of a 71) it’s still getting irregular readings, more erratic actually, any help or insight is great, thanks. The needle is bouncing in the higher end past 60 psi, until I give it gas and it settles down a little.
 

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Rickf

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You can always "T" in a mechanical gauge to get a second opinion.
 

luminous05

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You can always "T" in a mechanical gauge to get a second opinion.
I have a oil pressure reader coming in tomorrow I’m going to connect to see if it’s actually getting readings like that, I guess I’ll be updating this thread tomorrow
 

luminous05

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You can always "T" in a mechanical gauge to get a second opinion.
Okay, just got done with Manuel oil pressure test and it’s running normal, not bouncing, about 35 psi. Looking into if there’s a ground or something else going on
 

Ricko1966

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Your gauge and sender should match the year of your truck,why are you using 1971 parts?
 

luminous05

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Your gauge and sender should match the year of your truck,why are you using 1971 parts?
So it’s a 1985 truck with a 71 350 that had been previously swapped into it, I accidentally ordered a 85 pressure sending unit instead, but they looked identical. I didn’t know if it would make much issue
 

Ricko1966

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So it’s a 1985 truck with a 71 350 that had been previously swapped into it, I accidentally ordered a 85 pressure sending unit instead, but they looked identical. I didn’t know if it would make much issue
Well you accidentally ordered the right part. Use the 85 sender,do not order a 71 sender
 

mibars

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I wonder what's the best spot to tap a 2nd pressure sensor? On a filter base? Or any other spot?
 

Rickf

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I use a 1/8" short brass nipple and "T" off of the factory location.
 

Snoots

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You didn't by chance use teflon tape on the threads of the new sender? Also, check the wiring at the sensor connector.
 

luminous05

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You didn't by chance use teflon tape on the threads of the new sender? Also, check the wiring at the sensor connector.
I didn’t use any, if it didn’t come with it already on, what does that cause?
 

Ricko1966

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I wonder what's the best spot to tap a 2nd pressure sensor? On a filter base? Or any other spot?
There's already a spot on the drivers side just above the oil filter to plumbed to oil pressure. Or use a tee just behind the distributor.
 

dsteelejr

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I wonder what's the best spot to tap a 2nd pressure sensor? On a filter base? Or any other spot?
If you’re adding a second gauge to have a second opinion I’d add a wet gauge and it would be best installed behind the distributor so the tube has the least distance to travel, less chance of it chafing or breaking. An electric pressure sender mount anywhere. It’s easier to run wires than metal tubing.
 
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Snoots

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I didn’t use any, if it didn’t come with it already on, what does that cause?
No worries then. Teflon tape on ANY sensor will insulate it from ground.
 

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