Oil pressure ?

[mjr45]

Have a question re: oil pressure. I've put 2 new oil pressure senders on my 75 280 and still have a really low reading on the gauge. I replaced the electrical connector to the sender and I am sure the rest of the wire is intact. I know that oil is circulating well up into the head(don't ask), but the gauge reads low. I know that some of these old gauges aren't real accurate, so just curious if I should be real concerned about this issue? Thanks

Mike

[Zed Head]

You know that you won't really feel comfortable until you get a good number from a good gauge. You could pull the sender temporarily and install a mechanical gauge just to know what you're really getting. Or you could buy some fittings and plumb a gauge in permanently, and keep the sender (that's what my engine came with from a PO). Even if you get a sender that gives a high reading how do you know it's not erroneously high? False sense of security and all that.

The main issue with plumbing a gauge in is that the thread in the block is BSPT. An odd British standard.

[mjr45]

Thanx Zed, I've considered just putting in a mechanical gauge somewhere up front, but I kinda like a cockpit gauge just for the esthetics of it. British Standard huh, that should be fun to find!

[Zed Head]

Search "bspt adapter" on McMaster Carr and you'll find some options. You'll have to click through some parts to get details though and do some work to figure out what the gauge needs. I have some out in the garage, I'll get the part number if I get a chance.

I found the number from my old internet order. It's little bit long so raises the risk of being broken off if banged. But it has the right threads. Another option is the 3/4" close nipple, 5832T111.

5832T121 BSPT-to-NPT Threaded Brass Pipe Nipple, 1/8" Pipe Size, 1-1/2" L, Threaded Both Ends, Schedule 40

Edited March 12, 2014 by Zed Head

[siteunseen]

Does your '75 have the smaller one or the bigger one that looks like a fuel filter? My late '77 has the bigger one and it reads strong pressure even at idle although it gets lower when the oil is hot at idle. But at 3k RPM it reads 3/4's of the gauge.

1977 NISSAN 280Z Oil Pressure Sender / Switch

[grannyknot]

Along the line of what Zed is recommending you could also saw off the nipple of the BSPT sender and solder on to a generic oil pressure sender then using a fine drill to clean out any solder that made it into the hole.

[mjr45]

Site, its the smaller one with a single electrical connection.

Zed, thanks for the info.

granny, I don't think I have the skill set to do that, I was told that when it comes to soldering, I make a good welder.

Ill probably try to get a BSPT to NPT adapter and run some plumbing to put mechanical gauge close to the engine and then use another adapter to hook up the cockpit gauge. That way I'll know "real" pressure and still have a cockpit gauge for the "looks." Thanks

[zKars]

Somehow the engineer in me feels a bit 'dirty' suggesting this, but a million of us (slight exaggeration) have done the unthinkable and used a more commonly available 1/8" NPT threaded gauge or adapter fitting into the block without leakage and still manage to sleep at night. A purist might run a 1/8 NPT tap into the threads to form them a bit, but what works works. 1/8 BSPT is 28 TPI, which 1/8 NPT is 27 TPI so it seems like you really shouldn't do that but... Adapters are easily available from M-C as suggested.

To clear my conscious...

http://www.mcmaster.com/#bspt-to-npt-pipe-fitting-adapters/=r2rurr

Edited March 13, 2014 by zKars

[mjr45]

I think I've figured out how to do this with stuff from McMaster-Carr and for $75 I'll have a mechanical gauge in the engine bay about 3" from the block with the standard sender connected to the end going to the cockpit. Thanks for all the help.

Mike

[siteunseen]

I found the one I had that read low all the time. I read something about the newer style being more accurate so I bought one. For me, it worked. FAIW, which ain't much!

[grannyknot]

siteunseen, would you mind sharing the make and model number of that unit?

[siteunseen]

I can't remember where I bought it, I have the regular chain stores close by. But I could've got it from amazon.com or rockauto.com.

https://www.google.com/search?q=STANDARD+MOTOR+PRODUCTS+PS153&rlz=1C1BOFA_enUS494US494&oq=STANDARD+MOTOR+PRODUCTS+PS153&aqs=chrome..69i57&sourceid=chrome&espv=210&es_sm=93&ie=UTF-8

http://www.rockauto.com/catalog/moreinfo.php?pk=44198

Edited March 29, 2014 by siteunseen