1977 280z Radiator clutch fan engaged too frequent

[240zadmire]

yes.  It was disconnected from the sender unit.  I'll measure the voltage fluctuate when I'm home from work.

[SteveJ]

23 minutes ago, 240zadmire said:

yes.  It was disconnected from the sender unit.  I'll measure the voltage fluctuate when I'm home from work.

I don't think there is a need to measure the voltage fluctuation. That is how those meters operate.

I forgot to include an example. Here's a video I did of a fuel gauge operating. You can see the current fluctuating on the power supply. That is from the gauge operating.

 

Edited August 23, 2022 by SteveJ

[240zadmire]

Look like the voltage regulator has been replaced.  I’m trying to follow the instructions to adjust the voltage regulator but seem like there isn’t any screw to adjust the gap of the contact point.  Also, the instruction for adjusting the charge is conflicted.  One box says if it’s over 5.2v, replace and the second box say everything is in working order.  Perhaps they meant 15.2v?  Missing number 1?

[240zadmire]

Not sure howto go about over 5.2v is bad/good base on the service manual… anyway, I adjusted the voltage regulator.  At idle, the charge fluctuate at 5.6v.  Also at idle without load nicely around 12.7v and at 3000RPM, hovering around 13.8v, if the cigarette voltmeter as suggested any accuracy.    Still, better than +15v before.  Thanks for noticing the high voltage and suggesting the cigarette.  Smoking hot 🥵 

[Patcon]

So you figured out how to adjust it?

[240zadmire]

The service manual is the the original VR that has the screw to adjust the contact points, I think.  The one in my car is replaced I believe.

 
it’s harder to adjust this type than the one mentioned in the service manual.  However, it is adjustable.  The 2 screws holds T contact point.  It is shape like a T.  It can be moved back and forth .  The top of the T, I call it a blade, act like a spring tension.  Move closer to the screws strengthen the spring.  I think the coils below the top of the T, magnetized when energized.  It took me no less than 10 tried to get it under 14v.   Seem like idling voltage and driving voltage have different behavior.  One of the try I did, idling was 13v but while driving it was under 11v and sometime the charge light turn on/off while driving.

 

[240zadmire]

Alright folk

i changed direction a bit about mechanical gauge…. I bought another oil pressure sender instead.  This sender is a bit less resistance I think.  75ohms at 0 PSI.  The fitting is NPT instead of BPST, hence another adapter.  At cold start, oil gauge is very close to middle and when engine warms up, gauge points about middle.  I guess due to the less resistance, that’s why the gauge display as such.  But for sure having the gauge actually display something gives a bit a peace of mind.

another successful day is I finally pay attention to the AC vacuum.  I didn’t adjust it correct.  At idle, when AC is engaged, there’s a vacuum at the throttle body to increase RPM a bit to keep the engine healthy.

 

last couple of weeks, with you guys help, I’ve able to solve the flasher blown fuse, no heat at fuses box, voltage regulator look healthy. 
the next challenge is the fan clutch keep engaged too frequent.

 

 

[240zadmire]

I think I looked at this the wrong way.  Before the radiator flushed, buildup, calcium… prevent the heat from dissipate proper.  Hence, in turn not able to heat up the bimetal in the clutch fan that allowed it to engage as frequent as it is now.

today is heat record at my area.  Triple digits, 112 degrees at 10am time frame and I was driving for an hour on freeway.  The temperature gauge’s needle just a hair pass the F letter.  I think the engine is still within optimal operation.  The clutch fan engaged constantly.  AC was on the whole time and I experienced no lost of power.  It looked a little bit hot but I think it is ok.  Just annoyed the clutch fan is loud.  Hope the other drivers with obnoxious straight pipe still able to hear their own engine’s backfired 🙂

 

[SteveJ]

And the oil pressure looks good, too.

[240zadmire]

3 minutes ago, SteveJ said:

 

And the oil pressure looks good, too.

 

The voltage and especially the fuel gauge.  I want the fuel gauge always to be on the right side 😉