Fan Clutch?

rusty ol ranger · Apr 29, 2018

Im wondering if my fan clutch is bad...

Ive only had one ever fail, and that was on my 77, and when it failed it kept the fan engaged all the time...

But if you read my other thread "temp issues" youll see the issue im having. I had a feeling it was electrical untill last night when i spun the fan by hand and it seemed like there was no resistance there at all, the one on my 77 has some resistance to it.

What its doing is when you stop the gauge spikes up after you idle for 30-60 seconds, however, i noticed yesterday it seemed to be running around the "o" in normal, but then when i stopped it spiked to the top of the normal band (highest it has so far) for about 5-10 seconds, then it dropped back to "r". The oil pressure also dropped back to just under 1/2 way. The fuel gauge also spikes/drops during all this.

But oddly it was running up around "o" going down the road when warm, but the oil pressure was also around "n".

I know factory gauges arent great. But im just trying to figure out if its actually a mechanical problem. Ive felt the hoses and they dont feel abnormally hot, and the system is building pressure.

Denisefwd93 · Apr 29, 2018

rusty ol ranger said:
Im wondering if my fan clutch is bad...

Ive only had one ever fail, and that was on my 77, and when it failed it kept the fan engaged all the time...

But if you read my other thread "temp issues" youll see the issue im having. I had a feeling it was electrical untill last night when i spun the fan by hand and it seemed like there was no resistance there at all, the one on my 77 has some resistance to it.

What its doing is when you stop the gauge spikes up after you idle for 30-60 seconds, however, i noticed yesterday it seemed to be running around the "o" in normal, but then when i stopped it spiked to the top of the normal band (highest it has so far) for about 5-10 seconds, then it dropped back to "r". The oil pressure also dropped back to just under 1/2 way. The fuel gauge also spikes/drops during all this.

But oddly it was running up around "o" going down the road when warm, but the oil pressure was also around "n".

I know factory gauges arent great. But im just trying to figure out if its actually a mechanical problem. Ive felt the hoses and they dont feel abnormally hot, and the system is building pressure.

All considered, fan clutches are pretty cheap overheating insurance, I'm a big believer in 180 thermostats too

rusty ol ranger · Apr 29, 2018

Denisefwd93 said:
All considered, fan clutches are pretty cheap overheating insurance, I'm a big believer in 180 thermostats too

Thats where im at with it, but, time is at a premimum with me and the 77 has no brakes, and i hate racking miles on the 460.

I did use a 180* t stat when i changed it.

fastpakr · Apr 29, 2018

Does the fan clutch feel tight when you shut the engine down hot?

rusty ol ranger · Apr 29, 2018

fastpakr said:
Does the fan clutch feel tight when you shut the engine down hot?

Thats when i spun it. Lol.

RonD · Apr 29, 2018

180degF thermostat just lowers MPG and doesn't clean oil(burn off condensation) as well as 190degF, users choice.

But it has nothing to do with overheating, it sets "minimum" operating temp, so 10deg difference won't matter if engine has low coolant or other reasons for overheating.

SAE did a study in regards to coolant temp and engine life, and they set the 190-195degF thermostats as best minimum temp for gasoline engines, study was back in the mid/late 1970's I believe, and thats when Ford started using 190-195degF thermostats

Yes, it reads like you do have failed fan clutch, it should not spin when stone cold, move yes but not spin manually.
And after Radiator is warmed up fan should also not spin, should feel like when it was stone cold.

Fan should make a loud noise at cold start since it is locked to water pump RPMs, then after 5 seconds noise should go way, if you shut off the engine at that time then fan should spin easily, it is unlocked.

And an electrical issue as well, connect volt meter to battery after engine is warmed up, raise RPMs and see if voltage goes up, should stay steady at 13.5-13.7 volts at any RPM.
Turn on headlights and blower to high, voltage should stay steady
Let it idle, if voltage drops below 13.5v then you have a failed Field coil in alternator, not a big deal unless you idle alot.

Also to see if coolant temp heat spike at idle is real, turn on Defrost, Heat to HOT and fan to high
Feel the Defrost vent temp as you slow down to stop and idle, see if temp goes up as temp gauge does, it will if coolant temp is really going up

rusty ol ranger · Apr 29, 2018

RonD said:
180degF thermostat just lowers MPG and doesn't clean oil(burn off condensation) as well as 190degF, users choice.

But it has nothing to do with overheating, it sets "minimum" operating temp, so 10deg difference won't matter if engine has low coolant or other reasons for overheating.

SAE did a study in regards to coolant temp and engine life, and they set the 190-195degF thermostats as best minimum temp for gasoline engines, study was back in the mid/late 1970's I believe, and thats when Ford started using 190-195degF thermostats

Yes, it reads like you do have failed fan clutch, it should not spin when stone cold, move yes but not spin manually.
And after Radiator is warmed up fan should also not spin, should feel like when it was stone cold.

Fan should make a loud noise at cold start since it is locked to water pump RPMs, then after 5 seconds noise should go way, if you shut off the engine at that time then fan should spin easily, it is unlocked.

And an electrical issue as well, connect volt meter to battery after engine is warmed up, raise RPMs and see if voltage goes up, should stay steady at 13.5-13.7 volts at any RPM.
Turn on headlights and blower to high, voltage should stay steady
Let it idle, if voltage drops below 13.5v then you have a failed Field coil in alternator, not a big deal unless you idle alot.

Also to see if coolant temp heat spike at idle is real, turn on Defrost, Heat to HOT and fan to high
Feel the Defrost vent temp as you slow down to stop and idle, see if temp goes up as temp gauge does, it will if coolant temp is really going up

As always, good advice ron.

I looked into the fan clutch thing a bit more, i dony hear it run at startup, (but the truck is so loud i kinda doubt i would) but today i spun it after it sat for about 10 hrs at work, and it did only make a spin or two. Then, immediatly after i killed it, i checked again, same amount of spin.

However, oddly enough, today it didnt spike. I stopped at crapdonalds after work, let it idle in a parking spot two or 3 mins, it went up maybe a needletick.

However, today the other gauges seem to be functioning normal. I grab a voltmeter and check the charge like you said, i noticed when i was idleing that when i flicked the blower on it sounded like it put a noticable strain on the engine, almost like when you turn on the A/C.

The battery is staying charged though, and thats saying something cause its a 8 yr old motorcraft that was OE in the wifes escape, and was killed multiple times, pry froze, and god knows what else.

Denisefwd93 · Apr 29, 2018

The 180 vs. 195 discussion could go on forever I've been reading it for years in different places and so many different vehicles it's another one of those things that some people say it's good other people say it's bad just like when people remove the catalytic converter, or swear Allegiance to the electric fans. Closed loop as usually at the base of the discussion and if I understand my homework again closed loop is around 145?

RonD · Apr 29, 2018

Closed loop is when O2 sensors can be used reliably, they need to be heated above 600degF for the chemical reaction that detects Oxygen levels to work reliably.

If coolant doesn't get above about 140degF after 5 minutes or so computer will set a code for coolant temp problem, ECT sensor
But not sure it would cause computer to exit closed loop if O2s were working

Better MPG and cleaner oil is the only reason for 190degf t-stats
Lower engine temps can get better power, i.e. cooler intake manifold air so "heavier air" and more gasoline can be added
Not much difference but not 0 either, lol.

Most people who live in colder climates notice the engine is more "peppy" in the winter, colder heavier air is why
Air:fuel ratio is a weight ratio, 14.7 pounds of air to 1 pound of gasoline.
So the heavier the air the more gasoline you can add and the more power you get, Cold Air Intakes were added when vehicle makers added fuel injection for this reason, better performance

rusty ol ranger · Apr 29, 2018

I just did it because they 180 was in stock, the 195 wasnt...so what the hell.

I do run a 180 in my 97, and notice it doesnt run as hot when towing.

Denisefwd93 · Apr 29, 2018

Actually took it for a ride today got a CEL again.
172 & 38. Engine is cold, colder than the 180 thermostat, the fan clutch I think is good in the bad way, moving lots of air maybe too much?

I did put on a new IAC and cleaned the MASS

That's all I'll say here I don't want to hijack this thread I'll put it on my RR 94.

rusty ol ranger · Apr 29, 2018

Pry worried over nothing....heres where it sat and never moved...higher then id like but whats yalls opinion?

Only time i got it to creep upwards was when i got home and turned the blower on...i think i need to diagnose electric not cooling, the heater hoses wernt even hot enough for me to pull my hand away. T stat hasnt locked in failsafe, still hits temp in 3 or 4 miles@ 55* or so.

JerryC · Apr 29, 2018

My two cents, if you decide to change the fan clutch look closely at the fan. Mine looked fine until I pulled it out. It was full of cracks, I got a new one from LMC.
If you put a piece of cardboard between the fan and radiator you'll be a lot less likely to poke a hole in the radiator when you change the fan clutch.

rusty ol ranger · May 1, 2018

JerryC said:
My two cents, if you decide to change the fan clutch look closely at the fan. Mine looked fine until I pulled it out. It was full of cracks, I got a new one from LMC.
If you put a piece of cardboard between the fan and radiator you'll be a lot less likely to poke a hole in the radiator when you change the fan clutch.

Good advice on the cardboard.

I didnt really examine the fan itself. That being said however i do feel it sucking air thru the radiator. The cooling system on this thing seems tip top.

I think i might get a sunpro and put in just for peace of mind, but i truthfully dont think its actually getting hot. Really leaning toward some sort of electrical issue.

If it does ever creep higher then ill just crank the heat and pull over lol.

Denisefwd93 · May 1, 2018

Protecting the radiator is a very good idea even though the fan is plastic.

I don't think I've seen any plastic fan on any Ford Ranger is not cracked!

Fan Clutch?

2.9 Mafia-Don

Well-Known Member

2.9 Mafia-Don

Forum Staff Member

2.9 Mafia-Don

Official TRS AI

2.9 Mafia-Don

Well-Known Member

Official TRS AI

2.9 Mafia-Don

Well-Known Member

2.9 Mafia-Don

Active Member

2.9 Mafia-Don

Well-Known Member

Sponsored Ad

Sponsored Ad

Member & Vendor Upgrades

Truck of The Month

Recently Featured

Follow TRS On Instagram

TRS Events

25th Anniversary Sponsors

Check Out The TRS Store

Sponsored Ad

Sponsored Ad

Sponsored Ad

Amazon Deals