302 Z28 oilsending unit thread

firez · #1 08-05-2008, 02:47 AM

Does anyone know what thread the oil sending unit hole is? I am trying to put a sending unit in but the threads are built up with crap and I want to put a tap down through to clean it up.

**Salvatore** · #2 08-05-2008, 04:11 AM

1/8th national pipe tap. Its a tappered thread. Put some grease on the tap itself and hopefully it won't drop all the little filings down the block. You could also spin the oil pump and refresh the sending unit hole with fresh oil before you start the motor up.

firez · #3 08-05-2008, 05:41 AM

Thanks for the help,it seems a 3/8 NF 24 is very close also.

**TDW** · #4 08-05-2008, 02:41 PM

[ QUOTE ]
Thanks for the help,it seems a 3/8 NF 24 is very close also.

[/ QUOTE ]

Whatever you do, do not use the 3/8" tap. It will destroy the taper in the hole.

firez · #5 08-05-2008, 03:57 PM

Thanks for that help but I think that is what has been done already before I bought the car. Do you know if a heli-coil will work to fix this problem?

**TDW** · #6 08-05-2008, 04:37 PM

I have never heard of a heli-coil for a pipe thread. I would check the auto-parts store for a straight adapter that is 3/8"-24x 1/8" NPT. There are fittings like that in the brake tubing/fitting cabinets around here.

firez · #7 08-05-2008, 06:42 PM

I found a local machine shop that will make me up a adapter that will work with the problem I have encountered. Thanks Tony

PaulK · #8 10-28-2008, 08:07 PM

FYI - Future reference
They DO make a 1/8 NPT helicoil. McMaster Carr #91733A401 with tap #91711A251. Also 1/8 NPT is 27 TPI.

**TDW** · #9 10-29-2008, 02:49 AM

Thanks Paul. I stand corrected then.