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Oil Pressure Sender and Gauge specifications


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Hi there,

So I'm posting this up because I couldn't find it in a few hours of searching on all the various Z sites.

 

There's a bit of misinformation on which oil pressure sender to use and claims that only the original will work.

Here is what I have found (which is also missing from all the datsun service manuals).

The stock gauge reads roughly these readings at the following impedances from the sender.

 

1/8" below 0 psi - infinite ohms (open circuit).

0psi - 90ohms

60psi - 25 ohms

90psi - 12 ohms

 

I could only check these as i only had a couple 12.5ohm resistors to use.

Now I just bought the most likely candidate I could find on rockauto.

This happened to be:

 

BECK/ARNLEY 2010239 (201-0239) Oil Pressure Switch CAD$ 14.84 CAD$ 0.00 1

CAD$ 14.84

post-2104-0-95275400-1375934779_thumb.jpg

 

With a hose and my air compressor I measured the impedance at a few different pressures...

0psi - 88 ohms

20 psi - 44 ohms

60 psi - 25 ohms

90psi - 12.5 ohms

 

Yes, the sender is VERY VERY accurate to what the gauge reads.

 

Now a few things about the gauge...probably not good for a performance situation, but maybe usable to detect if your engine is getting weak (provided your sender stays in good shape). It is VERY slow to settle to the proper pressure.

 

With the signal wire shorted to ground, it will sweep from 0psi to 90psi+ in roughly 10 seconds. Because it is a heated strip indicator and not a motor, measurements tend to go 90% to their location in 20% of the time, but take 90% of the time to travel the last 10%. Just keep that in mind if you want to aproximate what PSI you have at a given RPM. it will likely take over 10 seconds for a PSI reading to be close.

 

Anyways, this gauge was from an early 260z, but I suspect other s30's apply.

this is more a reference post rather than a helpful DIY, but good for those who want to diagnose an inoperative faulty gauge.

Edited by mtnickel
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