Author Topic: 1/2” Oil Pressure Sender?  (Read 1141 times)

Offline Jon87V20

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1/2” Oil Pressure Sender?
« on: May 07, 2022, 10:12:28 PM »
The oil pressure sender in my ‘87 Suburban V20 started leaking. I ordered a replacement from Oreilly’s, but it ended up having a different diameter where it threads in. My engine has a fitting between the sender and the block. I think it was probably put there to help the sender clear the O2 sensor.

Anyway, the hole in the block itself is 1/2” too. Oreilly’s says they don’t have that and only have 1/4” or 1/8”.

Do I have some weird size, or is that common? I have a remanufactured 5.7. However, I had transplanted the sender and the fitting from the last engine so that was the same 1/2” as well.
1987 Chevrolet Suburban V20 Silverado
350ci TBI TH400 NP208

Offline bd

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Re: 1/2” Oil Pressure Sender?
« Reply #1 on: May 07, 2022, 11:07:56 PM »
The oil galley tap down near the oil filter should be 1/4" NPT.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Jon87V20

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Re: 1/2” Oil Pressure Sender?
« Reply #2 on: May 08, 2022, 09:36:17 AM »
Okay. Well that's weird. I wonder how both engines ended up having a ˝" tap. I'll go pick up an adapter today I guess. Thanks!
1987 Chevrolet Suburban V20 Silverado
350ci TBI TH400 NP208

Offline bd

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Re: 1/2” Oil Pressure Sender?
« Reply #3 on: May 08, 2022, 10:57:30 AM »
By any chance, are you confusing 1/4" NPT with 1/2" USS?
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Jon87V20

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Re: 1/2” Oil Pressure Sender?
« Reply #4 on: May 08, 2022, 12:03:57 PM »
bd, Not sure. I just measured across the diameter of the male side of the sender and it's ˝". So is the female side in the block.
1987 Chevrolet Suburban V20 Silverado
350ci TBI TH400 NP208

Offline Mike81K10

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Re: 1/2” Oil Pressure Sender?
« Reply #5 on: May 08, 2022, 12:33:46 PM »
NPT Thread Size & Pitch: 1/4-18 = Male Thread OD: 13.2 mm / 0.52 Inch = Female Thread ID: 11.2 mm / 0.44 Inch

Need to ask O'Reily if the 1/4 is NPT or Inches!
« Last Edit: May 08, 2022, 12:37:01 PM by Mike81K10 »
"Tell me and I forget. Teach me and I remember. Involve me and I learn." -Benjamin Franklin

Offline bd

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Re: 1/2” Oil Pressure Sender?
« Reply #6 on: May 08, 2022, 12:47:23 PM »
NPT Thread [measures] 13.2 mm [across]


This ^^^^^ should sum it up for you since 1/2" = 12.7 mm.  The two standards (1/4" NPT vs 1/2" USS) measure w/i 0.020" (0.5 mm) of each other.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)