1978 280Z - Won't restart when hot, all interior gauges, fan motor, backlighting not working

[Yarb]

Did you consider ordering the tee fitting where you will get a true pressure reading with the mechanical gauge? The adapter came from Glow Shift Gauges. The gauge and brass adapter Amazon. I had heard GlowShift sells on Amazon. Bought it directly from them. Have a p/n somewhere if needed.

[NocturnalEmber]

6 minutes ago, Yarb said:

Did you consider ordering the tee fitting where you will get a true pressure reading with the mechanical gauge? The adapter came from Glow Shift Gauges. The gauge and brass adapter Amazon. I had heard GlowShift sells on Amazon. Bought it directly from them. Have a p/n somewhere if needed.

If you have the part number that would be great!

[Yarb]

GlowShift on Amazon GS-FA-05

Marshall 100psi gauge and the elbow are easy to find. 
let me know if you can’t find it

[Yarb]

The brass adapter is 45 not 90 degrees. To tight to use a 90 degree adapter.

[NocturnalEmber]

3 hours ago, Yarb said:

Correct

I can't seem to find a thread chaser in 1/8" BSPT...anywhere.  I can find a thread tap in that size though.  Would it be safe to run a 1/8" BSPT thread tap through the hole in the engine to clean it out? Link below:

 

https://www.amazon.com/RC-HSS-BSPT-Pipe-Taper/dp/B07C73SG99

[Zed Head]

3 hours ago, NocturnalEmber said:

I want to run a thread chaser inside that hole though before I go trying to thread the replacement oil sensor in fully.  I did attempt to thread it in, and past a few turns I started meeting resistance so I immediately stopped, all threads look good though. 

It is normal for pipe threads to get tight after a few turns.  The hole is tapered, it's how they work.  The seal is created by the male end getting jammed in to the hole.  "A few turns" would be a few threads, so it sounds like it's fine.  You might be overthinking things.

You'll probably need sealant though if you try to use one of those adapters.  Because the seal is created when the pipe gets hard to turn you usually don't get to decide when you're done.   You crank it down and get what you get.  A good sealant gives you some adjustability.  This stuff works well, you can get it at Home Depot.

https://rectorseal.com/rectorseal-no-5-group/

Application Chart

[Captain Obvious]

Glad you got the busted off remnants of the old sender unit out of the block.

As for cleaning out the threads... The correct tapered tap would work fine. Two things I would keep in mind though:

1) Any metal you take off runs the risk of ending up in your oil galley. Take appropriate precautions.

2) Since this is a taper thread, any metal you take off will end up in the male stub threading in further before sealing. Don't go any deeper than you really need to. Clean it out... Don't make it bigger.

[NocturnalEmber]

I've got a bit of a conundrum here I'm hoping someone can help me solve (I apologize enough for this being off topic the past page or so related to my oil pressure sensor stud.)

So anyway...

The thread size for the oil pressure sensor is 1/8" BPST based on what I've looked up and what Yarb has confirmed for me.  I have a replacement Duralast sensor (I was able to get it locally, and its a two prong for my 78) that I mentioned, but something just didn't feel right when I tried to thread it in; The sensor threaded in a few micro turns, then hit resistance. While it is tapered like @Captain Obvious mentioned, that would explain it, but something in me just couldn't shake the fact that something may be "off." (Maybe its paranoia.)

So I went online and ordered an adapter that to my understanding (if someone wants to check me feel free) goes from the 1/8" male BSPT, to 1/8" NPT female.

My reasoning here, was I wasn't sure if since its a Duralast sensor, if most cars would be NPT and not BSPT, so I wanted to check before I started threading this thing into the block.

The verdict?   The Duralast sensor will thread into that adapter probably a good 2-4 full turns before it meets resistance, so a lot. 

If I try and thread the Duralast sensor into the block, it will go a few micro turns like i mentioned before it meets resistance (maybe this is because its tapered.)

 

I guess my end question is, how can I tell if this Duralast sensor is NPT or BSPT? it will thread into an NPT female adapter much further before it meets resistance than when I try threading it into the engine block.  Out of an abundance of caution, when i meet resistance I stop to avoid damaging threads.

 

Is it possible this sensor is NPT and not BSPT?  

Some pics below for thought; I'll also have my report on the ignition switch replacement after I get this situated.

 

Adapter is supposed to be 1/8" male BSPT to 1/8" NPT female

 

Adapter and sensor side by side

Gauge screwed into the adapter. The point at which I stopped here is the second I started to feel slight resistance. Threads are fine on both; The sensor threaded in a good few turns fine.  If it was BSPT like its supposed to be, wouldn't it have an issue going into an NPT female thread??  I can't tell if the adapter is tapered on either side' One of the comments on amazon did say it threads into a 280z block though. So there's that.

Edited September 18, 2023 by NocturnalEmber

[Zed Head]

Wouldn't be a surprise if an aftermarket part was made incorrectly.  Get an OReilly part and see if it's better.  Take the Duralast part back if Oreilly works.

Beck Arnley is almost certain to fit correctly.  But, wow, prices have gone up.

https://www.oreillyauto.com/shop/b/lighting---electrical/sensors/engine---drivetrain-sensors/oil-pressure-sensor-switch/9a4df8f34742/v/a/6637/automotive-car-1978-nissan-280z?q=oil+pressure+sensor%2Fswitch

[SteveJ]

5 hours ago, Zed Head said:

Wouldn't be a surprise if an aftermarket part was made incorrectly.  Get an OReilly part and see if it's better.  Take the Duralast part back if Oreilly works.

Beck Arnley is almost certain to fit correctly.  But, wow, prices have gone up.

https://www.oreillyauto.com/shop/b/lighting---electrical/sensors/engine---drivetrain-sensors/oil-pressure-sensor-switch/9a4df8f34742/v/a/6637/automotive-car-1978-nissan-280z?q=oil+pressure+sensor%2Fswitch

Rockauto is cheaper, even when you take shipping into account. Also, you can always search for a 5% discount code for RA. https://www.rockauto.com/en/moreinfo.php?pk=488596&cc=1209260&pt=4588&jsn=837

[Patcon]

I realize NPT is the wrong thread but it should probably thread in a couple of turns anyway. Something else seems to be wrong.

[Yarb]

My two cents would be to go the rock auto route. You have dodged one bullet already IMO.