1977 280z Radiator clutch fan engaged too frequent

[240zadmire]

Not sure how the oil sender unit should function… below are some photos at various points.   The light is dimmed at the bullet pin.  I also had a video showing the light is blinking constantly at the tip.  Will attach the video later.

 

 

[SteveJ]

The test light isn't a definitive test. However, here's how to test the gauge:

 

[240zadmire]

Yes.  I read that post.  The gauge works.  Ground the wire and within seconds the needle pegged to the right.

definitely there’s resistant in the sender unit.  The test light blinking but dim compare to the chassis.   I did rev up the engine but test light behave the same.  I wonder should the sender varies when engine is rev up?!. 
 

how do I measure resistance on the sender while engine is running?  Just connect ohm meter to the sender pin and to chassis ?

[SteveJ]

33 minutes ago, 240zadmire said:

Yes.  I read that post.  The gauge works.  Ground the wire and within seconds the needle pegged to the right.

definitely there’s resistant in the sender unit.  The test light blinking but dim compare to the chassis.   I did rev up the engine but test light behave the same.  I wonder should the sender varies when engine is rev up?!. 
 

how do I measure resistance on the sender while engine is running?  Just connect ohm meter to the sender pin and to chassis ?

Yes. Here's a link to resistance values posted by someone on Hybridz. https://forums.hybridz.org/topic/114259-oil-pressure-sender-and-gauge-specifications/

[Racer X]

3 hours ago, 240zadmire said:

Found the condenser.  How to check if it’s working?

I believe the condenser is for radio noise suppression. 
 

Testing condensers can be done using an analog ohmmeter. The link describes the process. I would add that removing the condenser completely from the car, and placing it on a non conductive surface is how the testing should be done.

https://www.reference.com/world-view/test-automobile-ignition-condenser-60004eb0d27238bb

[240zadmire]

One of the goodies came.  @Zed Head, @SteveJ, the voltage fluctuate up to 15.7v at 3000 RPM.

 

this is without any other load such as AC, headlights…. I had to turn on headlight while cruising the freeway to bring it down to 13.6v or so.

 

 

saw a clip on YouTube by @Dave WMopen up the regulator.  Has anyone rebuild it?

https://youtu.be/9qeYW_Rnoo4

 

[Racer X]

3 hours ago, 240zadmire said:

One of the goodies came.  @Zed Head, @SteveJ, the voltage fluctuate up to 15.7v at 3000 RPM.

 

this is without any other load such as AC, headlights…. I had to turn on headlight while cruising the freeway to bring it down to 13.6v or so.

 

 

saw a clip on YouTube by @Dave WMopen up the regulator.  Has anyone rebuild it?

https://youtu.be/9qeYW_Rnoo4

 

I have 'rebuilt' dozens of regulators including on Z cars. Pretty straightforward process. Lots of people throw these things away and buy new when they malfunction.

I might add that a point file is a better tool to use for dressing the contact points, over sandpaper.

[SteveJ]

8 hours ago, 240zadmire said:

One of the goodies came.  @Zed Head, @SteveJ, the voltage fluctuate up to 15.7v at 3000 RPM.

 

this is without any other load such as AC, headlights…. I had to turn on headlight while cruising the freeway to bring it down to 13.6v or so.

 

 

saw a clip on YouTube by @Dave WMopen up the regulator.  Has anyone rebuild it?

https://youtu.be/9qeYW_Rnoo4

 

Was 15.7 measured with a multimeter or read from the gauge in the car? This is why I like those cigarette lighter voltmeters. They are usually pretty close to a multimeter, and you can see the voltmeter and tachometer at the same time.

[240zadmire]

8 hours ago, SteveJ said:

Was 15.7 measured with a multimeter or read from the gauge in the car? This is why I like those cigarette lighter voltmeters. They are usually pretty close to a multimeter, and you can see the voltmeter and tachometer at the same time.

15.7 was from the new gadget you recommended.  One down side is that the headlight switch block completely the cigarette lighter.  I had to till my head right, down toward the center to take a peak 😉  Ahh well, it's an add-on, not by design I suppose.  I will see when I have some free time, will open the voltage regulator and see if I can rebuild/clean up.  For now, I'm turning on the headlights to keep the voltage down while on 3K RPM.

This post is definitely weird ... going to the doctor for a splinter removal and now all the doctors/specialists found bunch of other ailments 😉  Got to love owning a "classic" car!!!!!

 

[SteveJ]

Thanks for the verification. At 15.7, the charging system is running high. Is that how it has been running, or have you changed out the alternator or voltage regulator?

By the way, did you ever check the sending unit for resistance?

[240zadmire]

the oil sending unit resistance?  I probably did it wrong ... What I did was to turn on the voltmeter to ohm, stick one lead to the sender's bullet point, and the other pin to ground.

 

Using Light to test and notice the light strobing

 

 

Using voltmeter to measure the resistance.

 

 

 

[SteveJ]

The fluctuation of the test light is right in line with the operation of the oil pressure metering circuit. If you measured voltage to ground where you put the test light, you would see fluctuating voltage.

It would be easier for you to read the ohmmeter at the 200 ohm setting, but it appears as though the sender is working. It was disconnected from the wire from the gauge, wasn't it?