Found an old thread below: https://g35driver.com/forums/g35-sed...oling-fan.html Instead of bumping it back to life I'll ask my question in a new thread.

So what's going on with the fan clutch if you're able to turn it without force BUT it doesn't continually spin when you let go?

My 03 sedan's fan is running loud when the engine warms up & outside temp is above 50*. Also it keeps running past 20 MPH and sounds like a truck when accelerating.

Today I noticed the ambient temp sensor shows a temp that's way off vs what it actually is outside. It was 36* outside and the ambient sensor showed 72* on a cold start then slowly fell down to 36* after driving for 10 mins.

Could that have something to do with the coolant fan running loudly?

 

The ambient sensor (if you mean the temp read out near the clock) is mainly for the hvac controls, no connection to the engine tuning or cooling fan(s) to my knowledge. I wouldn't say its bad that you can hear the fan come on, that just means it doing its job. I have an 04, so electric fans, but when they come on high I can hear them at a stop light with windows up and radio off.
I would check into and make sure your car isn't running hot or near overheating, which would trigger the fan to come on and aid in cooling. Have you ever replaced the thermostat? Radiator in decent shape?
Maybe the fan clutch is failing or has failed, but I am no expert. All the cars that I have worked on with a mechanical fan, you can rotate it by hand and it will maybe spin a little bit when you let go, but not more than 1/2 a turn. My understanding is that they are fluid filled which acts as a dampener.

 

Thanks Andrew.... Mine is an early 03 sedan.
Just bought it. .. 1 owner 131K miles. . Mint
Records show a recent coolant flush and all maintenance up to date.

Unfortunateltely I'm not sure of they replaced the radiator and thermostat. Temp guage is smack dab in the middle and never moves higher.

When I rotate the fan it's not stiff at all. It'll stop immediately after I let go no matter how much force I exhert. Is that a sign the clutch is going bad?

 

@tiguy99 Are you talking about the mechanical or the electrical fan? I assume it's the mechanical fan, there is a spring inside that controls a mechanical/hydraulic clutch. As the spring gets hot it unwinds and puts pressure on the clutch which causes the fan to not slip as badly.

When the engine is cold you should be able to spin the fan somewhat freely, when the engine is hot and the fan is engaged it will be fairly stiff to rotate.

Cold engine if you spin the fan as hard as you can it will make 1/4 to 1/2 a rotation. Hot engine when you spin the fan it basically stops immediately and has significant resistance when spinning.

If you want to get a feel for how much resistance a cold clutch should have go down to a parts house and have them pull a mechanical clutch for you to spin by hand, that will give you a really good idea what it should feel like.

 

Hey Cleric!
Will do.

Thank you so much for the heads up.
I have a mechanical fan on my 03.

I've had a few Gs in the past all 05s with electric fans so this is all new to me.

I'll swing by NAPA this week and test spin one of their fan clutches.

:One a side note

Of course my car seemed to be driving normal this morning.
Its also colder outside this week compared to last week.

Ambient temp gauge showed 31* like it should along with the fan not roaring at all the entire way to work.
I could lightly hear the fan noise as the clutch engaged up to about 20MPH then it got quiet as I went faster.

Is that just how these mechanical fans are supposed to work?

 

It's probably just being drowned out by road noise as you go faster. However there is a point where the airflow due to speed matches the airflow that the fan is pulling at any given rpm and it doesn't have to work as hard. In fact at highway speed there's so much airflow across the fan that at a low rpm it's actually helping to PUSH the fan faster.

Also, about your ambient temperature probe. It's located behind the grill and in front of the radiator, near the right side. It's possible that your sensor is getting moisture into the harness. When I spray down the front of my vehicle I have to be really care of that because mine isn't a great seal. Typically it takes 30 minutes of driving for it to return to ACTUAL outdoor ambient temp. If it start to misbehave again you should probably inspect that harness, when you plug it back in it will always read the maximum value of something like 125 degrees F and it will slowly drop back down over about a half hour of driving.

 

Hey Cleric,

on YouTube claims this method can work on removing the fan clutch.

Haven't seen a thread on this forum confirming his method to remove the fan clutch.

what do you guys think about this method?

 

I've never been able to get a good read for spinning a fan clutch and feeling the resistance. in my experience, if the fan clutch has gone loose then you will overheat. If it has gone too tight, your car will feel sluggish and it will sound like a school bus all the time. I only get the school bus sound on mine on the hottest of days, when driving slow or sitting in traffic.

If you do replace fan clutch, get Factory OEM. I have wasted too much time with aftermarket fan clutches on Nissan's...

 

I want to tremendously thank both of you for your help with this.
In the past few months I've done a few tests and have some updates.

First breakthrough was when it started getting hot out.

We would drive around with the louder fan noise but when we got on the highway, the fan would stop sounding like a school bus just as cleric said.

That made me think maybe the fan is working as it should and its actually keeping the car from overheating.
BUT
That doesn't mean everything is all good....at least not yet.

So recently, I bent down by the grill area and located my single AC Condenser / Radiator cooling fan in the front.




To my surprise it wasn't spinning AT ALL. Even when the AC was turned on.

However I can hear noise like its trying to move but its stuck.

Long story short, I looked everywhere and found a replacement fan motor on Amazon.

Swapped it and tested it before putting it back.














Unfortunately it spun backwards blowing the air in a direction I don't want.



Feeling defeated, I put the old motor back but not before I checked the shaft, moved it with my pliers and tapped it a few times with my wrench.
Well, that did the trick as the motor started back up like nothing happened and spun my AC Condenser fan the correct way!

I put everything back together per the G35 Repair manual and went for a test drive.


Sadly the mechanical fan and clutch are still loud like before BUT slightly quieter if that makes sense.

I've checked the little fan multiple times in the last few days and its working normally.
Coolant temps have been in the 185-203* range while driving around in this 95* heat.

Now I'm wondering if the radiator is loosing its efficiency in keeping the temps down OR if I should just replace the fan clutch and radiator all together.
Any ideas?

 

That sucks about the Amazon motor running backwards, glad you were able to get the original fan motor working!
185-203* is pretty much perfect. 204* is when my fans come on.
I run 175-190 in normal 'around town' daily driving conditions, mainly due to the 6MT thermostat. Apparently Nissan/Infiniti built the 5AT cars with 180* thermostats and 6MT cars with a 170*.
I got the 170* ordering from Z1 (plus coolant hoses + z1 alum bleeder), not knowing they were different temps. My only tip that they were different was when the car would warm up quickly to 172* and then slowly rise 180-190 after installing it w/ hoses and a new radiator, when prior it would warm to 185-190* and stay there. At first I shrugged it off as all new cooling system, but later on I got curious and started looking at p/n's and then I read in the FSM and confirmed that they are in fact diff temps.

Last weekend I went for a drive on hwy 33 in the heat. Highest temp I saw was 213*, but I was working her hard going up hills and such (plus running the A/C). Cooled back down to ~195* on downhills, and level roads cruising was 190-203*.