1977 280z Radiator clutch fan engaged too frequent

[240zadmire]

Greeting folks

Not sure if this belong to Heat & AC or Engine & powertrain ...

Here goes

My radiator was serviced couple of months ago due to some minor leak at the top of the radiator.  The shop need to open up the entire top cover of the radiator to do a fix... They recommended to flush, and remove all of the build up over the year.  The fee for the job is about the same if I were to buy the new aluminum 3 rows radiator.  However, I like the stock looking and it also 3 rows radiator, so I agree with the job.  This is couple of months back before the summer.  All seem to be working well.

 

Recently, I notice the fan clutch engaged too frequent.  My recollection is that usually, the fan clutch engaged at around the temperature needle pass the vertical "F" letter that start showing the vertical bar.

Lately, the fan clutch engaged even before the temperature needle reaches the "F" letter.  This is happening even when the engine just start warming up to operation temperature.  Meaning when I start driving for about 10-15 minutes.  

Is the global warming start taking toll????

 

regards

 

Edited August 17, 2022 by 240zadmire

[Captain Obvious]

I don't have any input into your fan issue, but just wanted to ask... Are you driving on the road when you took that pic, or sitting at idle somewhere?

Reason I ask is, the oil pressure is low if you're out driving around. It would be OK for idle, but not for higher RPMs. Based on your posture on the road it looks like your RPMs should be higher than idle.

 

[240zadmire]

@Captain Obvious

When the car cold start, the oil pressure is about 1/3 or even close to 1/2 on the gauge at idle.  As the engine warms up, the oil pressure drops.   And while on freeway cruising 70MPH, I get a constant 1/5 or so.  I learn to live with it as at idle, I can see oil splashing on the camshaft when I open the oil cap.  Who knows, it could be one of the connector also corroded and/or greenish.  I did have brand new oil sender unit with single pin.

The picture above I took when I was in 4th gear.  Just get off of from a green light.

 

The voltage meter sits right between 12 and 16 volt indicator.  As I step on the accelerator pedal, it reaches close to 16 volts constantly.

As for the fan clutch, I don't think it is malfunction.  I've ran through the diagnose test such as spin the fan at cold and right after driving a car for a while and observe how it spin.  All seem to indicate it is functioning as it should be.  

With my limited knowledge of how the clutch fan suppose to work ... seem that there is bimetal and/or as the oil in the clutch warms up, viscosity thins that allow the tiny balls or metal expands that allow the fan to run close to or at speed of the engine RPM.  If my memory serve me right, cruising on the freeway, I never heard the clutch kick in.  Granted lately the weather is a bit warmer, but the weather in the morning between 9-10 shouldn't change that much last couple of months.

It could be coincident is that After flushing the radiator, I used the coolant made for modern Asian cars, Zerex blue color.  I can't remember which brand I used before but it was green.  The IR temperature I got from top of the radiator was about 170F on top and 140F on bottom.  Close to the thermostat was about 180-190F.  I think the engine temperature is within optimal operation but just annoying hearing the clutch kick in too early and often.

 

 

 

Edited August 18, 2022 by 240zadmire

[Freez74]

Did the shop replace your fan clutch when they worked on the radiator?

[Racer X]

A couple of things.

Is the bearing in the fan clutch OK, or is it loose?

You mention the temperature gauge points to “F”. There is no  F on the temperature gauge. The picture you posted shows the temperature is in the middle of the range, so this is good.

Does the fan clutch engage and stay engaged with the engine at this temperature?

What does the temperature gauge do just before, and then after the fan clutch engages?

 

One point I would like to make is that the type of coolant has zero effect on the operation of the fan clutch.

 

Also, the oil pressure. The stock gauge in the Z is electric,  nothing more than an approximation. Having a good, quality mechanical gauge is the only way to know what the oil pressure is. Also, the oil pressure will change, showing a higher reading at idle when the engine is cold and getting lower as the engine reaches operating temperature. The rule of thumb is 10 pounds of pressure for every 1,000 rpm of engine speed, so 10 psi at idle is fine.

 

 

 

 

 

[SteveJ]

5 minutes ago, Racer X said:

You mention the temperature gauge points to “F”. There is no  F on the temperature gauge. The picture you posted shows the temperature is in the middle of the range, so this is good.

But there is an F on the temperature gauge.

[Racer X]

27 minutes ago, SteveJ said:

But there is an F on the temperature gauge.

Thanks Steve. 
 

Been too long that I’ve seen one in person, and the OP’s picture isn’t good enough for me to see it.

Still, looks like the temps in his car are normal.

 

[SteveJ]

Just now, Racer X said:

Thanks Steve. 
 

Been too long that I’ve seen one in person, and the OP’s picture isn’t good enough for me to see it.

Still, looks like the temps in his car are normal.

 

Agreed. Assuming a linear response in the gauge, I wouldn't worry unless the needle was clearly to the right of F and staying there.

As for the oil pressure, I know I've linked the parts a couple of times now for putting an adapter and mechanical pressure gauge on the engine to allow both gauges to function.

[240zadmire]

I took the radiator to the shop and put back afterward.  It was relatively easy by removed the radiator shroud and able to pull the radiator off.  The fan was intact during the whole operation. 

 

the fan clutch, thermostat, coolant temperature sensor are couple of thousands miles old.  The clutch has resistant both at cold as well as when the engine was off from a long drive.

My logic behind the coolant brand is that as the radiator fan draws the heat from the radiator, it heats up the clutch fan that allows the clutch fan to engage.   If the coolant boiling point is too low/high, it might indirectly affect the clutch fan engage prematurely.

 

when the clutch engaged, I’d say about less than 30 seconds then the clutch disengage.  I don’t think the car is any hotter than before.  In term of where the temperature needle was… when the clutch engaged, needle gradually went down to middle and the clutch disengaged.  The needle never completely pass the letter F.  It just one of those things I noticed that behave differently than it used to be. 
 

take a look at the photos below.  This is at idle at red light after 15 minutes of driving in the morning.  Around 8:10am.  The outside temperature was in the low 70F.

as I stepped on the gas pedal from the red light, the clutch fan engaged, around 3rd gear, then disengaged after couple of seconds.

 

[Yarb]

Install a mechanical gauge. T adapters are available 

[Zed Head]

This thread is a bit bizzaro.  I did learn something about the fan clutch though.  Didn't realize that Nissan had designed an RPM set point into it.  Off? at 1600 or?  to? 2500 RPM.  Not really clear how solid the limits are.  Pretty interesting.  Introduced in 1973 apparently.  Not clear what year you're working on though.

I think that your biggest concern might be your overcharging.  That will boil your battery and overheat numerous electrical components.  Your voltage regulator is not regulating.

 

Edited August 18, 2022 by Zed Head

[Freez74]

I have a replacement clutch from Rock Auto and it does not seem to disengage at highway speed.  Rather annoying.  Not sure what brand it is.