Oil pressure ?

[Zed Head]

I picked up one from the wrecking yard a while that works great. Matches my mechanical gauge. It has a rubber cover, and a wire with a bullet connector. Looks like the one in this link except the wire is black.

Amazon.com: Sankei Switches Oil Pressure Sender: Automotive

[Captain Obvious]

Somehow the engineer in me feels a bit 'dirty' suggesting this, but a million of us (slight exaggeration) have done the unthinkable

I'm gonna go a little bit further with the engineer stuff and ask... Are you guys really sure that it's a BSPT at all? Have you checked yourself? Does anyone have corroboration from anyone who has actually checked? Does someone have a spec drawing for the oil pressure sender? Are we really really sure that it's a British spec in the first place?

I've heard this BSPT thing here a whole bunch for the plumbing fittings, but personally... I'm skeptical.

To clear my conscious...

Haha!! Clear your conscious? Sounds like you had one too many?

[Zed Head]

You raise a good point about BSPT. I searched around the interweb on just generic "japanese pipe thread" and the word seems to be that Japan used British standards for pipe threads, both straight and tapered. Car guys, tractor guys, various official-looking documents. But I've never seen an official Nissan document.

I dinked around just now in the garage though and find that if the female fitting is big enough (I had a spare 1/8" union) , both thread standards will start in the hole, one just goes farther. But they both engage enough that they would probably seal with Teflon tape or pipe dope. If the hole is big enough.

Which exposes the real problem with the L6 block oil sender hole - it's just too small to easily start any adapter or pipe nipple. For whatever reason Nissan didn't drill and tap the hole as big as they could have. The pressure senders seem to taper down to a smaller end, which generally fits the hole (I have three old ones to look at). So if you decide to just force an NPT fitting in there, pick through the hardware store bin and find the smallest nipple end that you can. Maybe shave, file or sand the end threads down also so it has a better chance of starting. Or run a die farther up the nipple to cut the end down to size.

[Stanley]

Haven't messed with the oil pressure sender, but I some other stuff on the motor I've tried is BSPT. SU's all metric. Originally plugged the balance tube holes with NPT and Teflon tape, but when I replaced the NPT plugs with BSPT they screwed in way nicer. Also the thermostat hose barb for the hose to the intake manifold heater tube is 1/4" BSPT. The hose barb for the heater hose connection of the back of the head is also BSPT.

On the mechanical fuel pump (Kodansha), I tried a 1/8" NPT tee for the F.P. gauge, it wouldn't screw in at all. A 1/8" BSPT adapter (from M-C) worked perfect.

Edited March 31, 2014 by Stanley

[Captain_Zeros]

Every pipe fitting on an early Z is British thread.

The reason for confusion is that at and above 1/2" they have the same thread pitch, just slightly different profile threads, so they'll screw together and even seal (I wouldn't trust high pressure systems, but nothing in our cooling and oiling systems can really be considered "high pressure" in industrial terms).

HOWEVER: below 1/2" the thread pitches do not match up, trying to put a 18 tpi fitting into a 19 tpi hole is a recipe for a bad day.

Another note: Teflon tape is NOT a sealant, it is merely a lubricant that lets you crank down on the fittings a bit harder to get a tighter mechanical seal. The more you know!

[Captain Obvious]

Thanks for the info guys.

I think I've got a spare oil pressure sender in the garage somewhere and I know I've got NPT taps down to 1/8. If I get a chance I'll take a look and see about how many turns you would get before things start binding.