Fan clutch diagnosis

[Cfbrenton1]

Ok, so at idle the other day after dragging the local softball field on a really hot day, I left my truck idling and came back and noticed it was running super hot. The temp needle was in the red. I am thinking it is my fan clutch, so I am posting this video to confirm. I am a novice at fixing things, but learn more all the time. Please excuse me if what you see in this video is a very obvious diagnosis. I just wanted to check in with the pros before I start dismantling my fan. The fan seemed to be running slow, so based on what I read, I decided to try to stop it with a newspaper, which I did quite easily. Also, when I released the newspaper, it restarted very slowly. Am I correct in determining that my fan clutch isn't working properly? If so, Should I replace it or do that thing with the hobby oil that others have done? Thanks!

 

[NLXTACY]

Yeah, it's useless. Literally useless. Driving your truck and having the air flow thru the front of the radiator would be better.

edit: wait, this assumes the motor is warmed up and not cold.

 

[SUMMIT CRUISERS]

You definitely need a new fan clutch or replace the fluid with 10k or 15K cst silicone RC differential fluid. It's your choice. I have changed fluid in 3 or 4 clutches and all perform perfectly during the hot summer. I even changed the fluid in a new one that wasn't performing well at low speeds/high altitude climbs. 15K for Oklahoma is works great here.

 

[Cfbrenton1]

Yeah, it's useless. Literally useless. Driving your truck and having the air flow thru the front of the radiator would be better.

edit: wait, this assumes the motor is warmed up and not cold.

Motor was hot.

 

[NLXTACY]

Motor was hot.

Then it's useless

 

[fj80pb]

Hi there.
That clutch is gone mate! (good idea to post the video)
If you decide getting a new one instead of rebuilding the old with 10 or 15K fluid, as quite some members here have done, here's the OEM P/N: 16210-66020 (is the so-called blue clutch). I got mine from Cruiser Dan a few weeks a go and it works like a champ (great and cool AC while in low speed traffic or at idle)
Whatever solution you choose do it ASAP. Overheating the engine just maximizes the chances for head gasket failure.
Good luck!

 

[Cfbrenton1]

I am going to try to go with the silicon oil solution...unless someone really thinks I shouldn't.

 

[fj80pb]

If you decide changing the fluid, there's a video that you might find helpful

 

[Tools R Us]

That clutch is "off", depending on the conditions, a normal state for a clutch. The clutch is activated, turned "on" by the temp of the airflow out of the radiator, so if that airflow is over say 150F it should be "on" and the clutch has lost it's drive and/or the thermo valve is bad. The other possibility is the radiator, if it's restricted, will not efficiently transfer heat to the air, so the motor can be hot and the airflow not have sufficient temp to engage the clutch.

 

[Cfbrenton1]

So are you saying that my fan clutch is likely not the problem? Or maybe it is, maybe it isn't?

 

[surfpig]

So are you saying that my fan clutch is likely not the problem? Or maybe it is, maybe it isn't?

Y E S

 

[Tools R Us]

... maybe it is, maybe it isn't?

Not enough info to make a solid diagnosis. How old is the radiator, looking into the cap hole, how does it look, are the tube openings clear or restricted? If you have a IR temp gun, warm the motor, run the gun slowly over the tubes/fins side to side on the face of the radiator (best done from the front under the condenser) the temp should be consistent, if some areas are cool and others are hot, likely a clogged radiator. Could be the clutch, could be the radiator, could be both.

 

[inkpot]

So are you saying that my fan clutch is likely not the problem? Or maybe it is, maybe it isn't?

Make sure the center of your radiator is not blocked with dirt, mud, leaves, feathers, etc. If it is then there is no airflow thru the center of the radiator which in turn heats and cools the themo spring valve on the front of the fan clutch. John

 

[landtank]

another check would be to let the truck sit over night and check the clutch in the morning. Even though the clutch is cold there should be a good amount of resistance when trying to turn it by hand. That would be with the engine off, BTW. If it turns easily then there is something wrong.

You might have read about start up roar and this is along the same lines. Over night the clutch fluid settles and on that first start in the morning there should be a roar coming from the fan. If it turns easily and no roar then there is a problem with the clutch and a fluid exchange might help revive it.