Fan clutch Not Disengaging

[BlazerLT]

I have been experiencing a vehicle that takes quite a while to warm up, that is running cold on the highway at highway speeds and is getting very poor fuel economy.

My last tank was exactly 12.7MPG.....which is horrible.

Today I noticed that the engine was warming up much faster than before and had some more pep too it which was nice to see. Then it seemed like it started to lose some power on the highway at full operating temperature and I watched the temp gauge as it dropped to a quarter on the dash.

1.) The thermostat is new and is opening properly.
2.) When slowing down I can see the temperature gauge slowly creep up as the engine rpms get lower. Temperature is directly related to speed and engine rpms.
3.) Pressure test cooling system and it is 100% perfect.

In the morning, the fan or the water pump makes a weird screeching noise when it is cold, never when the temperature is above 32f.

Come to think of it, I was in line to get a coffee to go in drive thru and the rythmic screeching noise got more and more constant as the engine warmed up.

Do you think it is the fan clutch staying partially engaged, sucking power, overcooling the cooling system and scrreching in the morning?

[ericn1300]

fan clutches sticking are common. there are after market conversions kits for electrical fans and i remeber a post from a long time ago on how to use a junkyard Taurus fan to convert to electrical. i'll try to find it again.

[DelCoch]

Ok, here are my thoughts. Radiator cools at highway speed, no doubt this is due to airflow through radiator. Radiator doesn’t cool at slow speed, no doubt a lack of airflow through radiator.

If the fan clutch was staying partially engaged it would cool at slow speed, plus I doubt it would cause that much of a loss in MPG. The symptoms you indicate suggest a fan clutch that has failed, thus the fan not running.

Without being able to hear the screeching noise, it’s hard to tell whether it would be the fan belt or a bad bearing. Can you put a sound clip on here for us to listen to??

I would get a mechanic’s stethoscope and try to pin point the source of the screeching noise.

I’m putting my money on a bad bearing, either in the water pump, idle pulley, AC pulley or somewhere in the fan belt routing. If a bad bearing is locking up it will cause the fan belt to screech and would also account for the poor MPG and lack of cooling at slow speed. Last but not least, it could also be a worn out fan belt, or a non functioning tension pulley, both of which would meet all the symptoms you described.

Just the fact that the engine is not reaching operating temp could account for the bad gas mileage.

[BlazerLT]

It gets up to proper temperature when the engine is at lower speeds and the thermostat opens up perfectly.

The stat is under 3000miles old. It just really sucks the power, nothing super crazy like it as locked up and roaring, but enough to notice the drag a lot.

[DelCoch]

Sounds like a bearing has seized up and it's putting a lot of drag on the fan belt. In which case the belt will break before too long. But, it could be something else, depending on where the screeching is coming from.

[BlazerLT]

Not a rubber squeak or a squealing belt at all.

It does sound like a dry bearing or something along that line.

[Blue Bowtie]

The silicone oil in the clutch fan hub will be a lot more viscous in cold weather, and take longer to shear away and allow the fan clutch to freewheel. If the thermostatic spring on the front of the fan clutch hub is covered with dirt and debris (as many are) the fan clutch may take even longer to break away and freewheel. And a "stuck" fan can suck a lot of power.

The bearing-like noise could be anything, including the clutch hub. Since we can't hear it, you're on your own to find that one. Just a dumb-guy question (usually the only kind I ask since I'm so dumb) but is the coolant concentration adequate, or is there a possibility of some freezing in the water pump?

[BlazerLT]

Originally Posted by Blue Bowtie

The silicone oil in the clutch fan hub will be a lot more viscous in cold weather, and take longer to shear away and allow the fan clutch to freewheel. If the thermostatic spring on the front of the fan clutch hub is covered with dirt and debris (as many are) the fan clutch may take even longer to break away and freewheel. And a "stuck" fan can suck a lot of power.

The bearing-like noise could be anything, including the clutch hub. Since we can't hear it, you're on your own to find that one. Just a dumb-guy question (usually the only kind I ask since I'm so dumb) but is the coolant concentration adequate, or is there a possibility of some freezing in the water pump?

Coolant is one year old and mixed 60/40.

The weird thing is lately, when I start the truck the engine will rev up faster than usual and spin up like it has no load and all of a sudden the fan will kick in and drag it down. Kinda like it was free-wheeling.

Only lately has this been happening though since it has been cold.

I called around and I can get a fan clutch locally in stock so what the hell, might as well swap it in.

With the fan out I might take it for a test spin seeing it is 20f our here and there is no chance of overheating.

[DelCoch]

It probably would be a good idea to pop the hood and see if the fan is ready to fall off and go through the radiator.

If you replace the fan clutch, I suggest going with the Heavy Duty one.

[BlazerLT]

Welp, I replaced it, quite an easy job and can be done in under an hour.

The old fan clutch definitely has something wrong with it seeing it freewheels with little or no resistance when cold and when hot. I put it on a stove to heat it up and it did nothing but like to freewheel after about 2 revolutions.

The new one is a lot stiffer and like to roar pretty loudly when you first pull off when it is cold. At about 2000rpms it disengages and only come back on when you sit for a bit.

The truck does warm up a lot faster.

I think this was my weird dry squeaking noise. I don't think there is any fluid left in the old clutch.

[DelCoch]

Be interesting to see if you gas mileage comes back up.

[BlazerLT]

Now one thing I notice that is happening is that the fan roars like crazy the first time you start it for about 5 minutes and when you first take off when driving it, then it quiets down and is vitually undetectable.

I have heard this is normal. The only reason I didn't hear it before is seeing the clutch was shot. By the feel of it, the internal valve is gone inside.

[DelCoch]

I don't think the factory fan clutch is all that good. I replaced mine with a heavy duty and it does the same thing you're talking about, even in cold weather. Before I replaced it I couldn't hear it engage at all, and that is why I replaced it. Made no difference in my cooling though, as I still have an overheating problem in 90+ weather even with a 16 inch elec fan added. Go figure on that one. I think next spring I will replace the radiator, as that's the only thing left to replace in the cooling system.

[BlazerLT]

Originally Posted by DelCoch

I don't think the factory fan clutch is all that good. I replaced mine with a heavy duty and it does the same thing you're talking about, even in cold weather. Before I replaced it I couldn't hear it engage at all, and that is why I replaced it. Made no difference in my cooling though, as I still have an overheating problem in 90+ weather even with a 16 inch elec fan added. Go figure on that one. I think next spring I will replace the radiator, as that's the only thing left to replace in the cooling system.

Replacing my rad made a difference.

I am holding the clutch here now and it has zero resistance after three revolutions. It is essentially free-wheels.

The clutch for sure was the metallis squeaking noise from my front end when I started it up cold, thank god it wasn't the water pump. The water pump is turning perfectly, zero resistance when I spun it with my hands. Smooth as silk and no leaks.

This fan will do wonders this summer to keep things cooler.

Overall I am happy, though I am sick of replacing shit on this truck. Probably the water pump will go now seeing I was messing with the pully.

Man, got to get thet 300C before this truck makes me broke.

[ericn1300]

Originally Posted by BlazerLT

Man, got to get thet 300C before this truck makes me broke.

a 300c is going to break your bank faster than fixing your truck. just the down payment is more than you've probably spent so far. i can replace a lot of shit on my truck for just what you're gonna pay for insurance.

with insurance, principal and intrest paid to the bank a $30K vehicle will cost you close to $40K. be careful, my daddy always told me if you can't pay it off in less than 3 years, you can't afford it.