Brand new fan clutch - overheats at idle?

[JJorgensen52]

So I just switched my OEM fixed fan for a clutch fan setup tonight. During the process, I swapped the clutch for a new one (TorqFlo unit from Autozone). I noticed when I pulled the clutch from the box that there was a small amount of fluid on the face of it, but nothing that seemed significant.

Installed it, works great, my truck doesn't sound like a turboprop anymore on the highway, but I'm now overheating at idle. Or, at least it got up to the end of the green zone on the gauge and I chose to not see if it would stop . I had zero issues before I swapped fans.

From the reading I've done on clutches, it seems that if the fluid leaks out, they won't spin as fast as they should, thus causing low speed overheat.

Has anyone ever had this experience, a clutch bad right out of the box? I'm going to see if I can return it tomorrow and get one that doesn't show signs of leakage - any other suggestions?

[leftybass209]

Take it back and get a new one. I'm running the same clutch without a shroud on a 3 row champion radiator and it can idle in my garage for 30 min and doesn't overheat. It's been 98+ here all last week too.

[mechanicalman]

Yes take it back and don't take no for an answer and don't accept one that has leaked. Usually the box the fan clutch comes in will say something like "this end up". Probably was sitting upside down during shipping or on the shelf.

[leddzepp]

Take it back and swap in a new one. It should not overheat at idle, and the fluid leak means it is defective.

[JJorgensen52]

Thanks for the suggestions

I went in today, got a new clutch that wasn't leaky (and interestingly, despite having the same part number is not *quite* the same).

Just went out for a test ride, and it's good on the road, fan stays quiet as it should, but it's still getting warm when stopped. This fan is definitely speeding up as the truck gets warmed up.

I'm thinking, at this point, that this fan moves less air at the same speed as the old fixed blade, and I've now uncovered a radiator that's half plugged up from the previous owner hardly driving it.

Any suggestions as to the best radiator solvent? I've used the HD Prestone stuff before, seemed to work okay. I've also heard of using CLR.

[mechanicalman]

How deep is the fan into the radiator shroud? Is it sunken in a ways, or sticking out or about halfway in and halfway out? Sometimes swapping a fan for a fan clutch can result in a blade depth change into the shroud.

How many blades are on your fan? Even a good fan clutch setup will still sound like a turboprop when it's working hard like on first start-up and when the engine is hot. I assume it's the exact same diameter as the old fan.

Also, keep in mind if the radiator is half plugged and the engine is getting hot, the radiator is not transferring the heat to the air flowing towards the fan clutch, thus the fan clutch will never get the signal of how hot the coolant actually is and thus not lock up enough.

You did get a "thermal" fan clutch, right? With the coil spring in the front exposed to the airflow?

I've seen some really good deals on aluminum radiators on e-bay, and new brass ones are reasonable now as well. CLR or any other cleaning agent will likely make it leak, but seeings how it's half plugged it's worth the risk as the only other alternative is to replace it. They make a device that stores air and has a trip lever that delivers a high pressure high volume of air to blow out a radiator I've actually used one and they will blow out a lot of crap but my car still overheated until I replaced the radiator.

If you replace the radiator, do a full fresh water flush on everything, drain the block and blow all the water out of the heater core and clean out the over-flow jar if you have one. If you have aluminum parts on your engine or an aluminum radiator, use dex cool mixed with distilled water, or the pre-mixed (should say mixed 50/50 coolant distilled water).

NEVER put tap water in your engine's cooling system. It's heavy with calcium and that's what clogs your radiator. I know, so and so will chime in and say he did it for the past 50 years and he had no problems. Look at your old radiator tubes and that white stuff is calcium.

[BruthaMan]

Not sure on solvent, but Vinegar is a great all around natural cleaner that also works good on rust.

It's pretty straight forward. 4-5 gallons of white vinegar and drive around some for a few days. You'll be amazed at what will come out.

Tons of information on this:

https://www.google.com/?gws_rd=ssl#q...clean+radiator

[JJorgensen52]

Originally Posted by mechanicalman

How deep is the fan into the radiator shroud? Is it sunken in a ways, or sticking out or about halfway in and halfway out?

How many blades are on your fan? I assume it's the exact same diameter as the old fan.

It's a 6 blade fan, 18" diameter as the 4 blade fixed fan was. It sits just level to the shroud - meaning the backs of the blades are close to flush (they stick out just a tad). Yes, the clutch is thermal.

It moves plenty of air, but once it started getting hot I got out and felt the radiator and it's definitely only getting warm in the lower portion of the core.

Oddly, this truck has a 4 core radiator in it now, I would have expected a 2 core on a 307. Either way, I'll replace it in kind if need be (I prefer copper/brass units), but I'm hoping to save it if I can. It appears to be in excellent shape, cosmetically, no real corrosion to speak of or even damage to the fins.

I had not heard of vinegar before, but that's a good thought. It works great on this kind of buildup in plumbing so why not?

[BruthaMan]

Originally Posted by JJorgensen52

I had not heard of vinegar before, but that's a good thought. It works great on this kind of buildup in plumbing so why not?

I keep vinegar in the garage for everything. We used it in my son-in-law's 2001 Silverado. He drove it back and forth to work during the week, then on the weekend, we drained it out, filled with water again, then drained that, then antifreeze.

One other thing that may, or may not be of help. I had to replace my fan clutch earlier this year and came across several posts on the forum that recommended using a fan clutch for the late 80's 454 Suburbans. It's a "heavy duty" fan clutch. That's what I used on my '72.

http://67-72chevytrucks.com/vboard/s...ad.php?t=86293

Hope that helps.

[mechanicalman]

Originally Posted by JJorgensen52

It's a 6 blade fan, 18" diameter as the 4 blade fixed fan was. It sits just level to the shroud - meaning the backs of the blades are close to flush (they stick out just a tad). Yes, the clutch is thermal.

It moves plenty of air, but once it started getting hot I got out and felt the radiator and it's definitely only getting warm in the lower portion of the core.

Oddly, this truck has a 4 core radiator in it now, I would have expected a 2 core on a 307. Either way, I'll replace it in kind if need be (I prefer copper/brass units), but I'm hoping to save it if I can. It appears to be in excellent shape, cosmetically, no real corrosion to speak of or even damage to the fins.

I had not heard of vinegar before, but that's a good thought. It works great on this kind of buildup in plumbing so why not?

Sounds like you have it narrowed down to the radiator. Like you say, vinegar works good on calcium buildup so it will likely help. Keep in mind you might have steel head gaskets, and vinegar could take them out. But if it does, they likely needed replaced anyway. The newer fel-pro steel gaskets are great, easy to install and are even offered with a rubber coating, and new head bolts are cheap and twice as good as the original. Let me know if you need me to help you find any parts.

[JJorgensen52]

Just for reference, here are the parts I used:

http://www.autozone.com/autozone/par...312_9163_3018_
Fan blade PN 220618 (It says aluminum in the description but is in fact steel)

http://www.autozone.com/autozone/par...9_201566_3018_
Thermal clutch PN 922747

I also replaced the starter tonight, so I will go pick up some vinegar in the morning when I return the core and see if that does the trick.

[Stocker]

Sounds as though your clutch fan is the right size, fits in the shroud like it should, and is working properly. One thing is odd though, you said it doesn't pull as much air than your old 4-blade fixed fan. If it gets hot enough for the clutch to engage, it should pull more air, not less, even at idle. If you get any possible radiator problems fixed and still don't think your fan is moving enough air, try switching to a 7-blade. That was OEM on mine with factory A/C, and overheating has never been a problem.

[Freddo]

Another thing worth considering is some radiator shops have a flow tester.
Call around & check to see if any local shops have one. If you take your radiator off & take it in, they will usually check them for free or for a nominal charge. (At least in our part
of the country they will.) A good radiator person can give you the gallons
per minute specific radiators are capable of flowing. I have seen these that
were supposed to flow 22 gallons per minute that were plugged up enough
that they only flowed 10 gpm. The caustics most radiator shops use are more
effective than vinegar(although vinegar sounds like a good idea.) I have seen
a 25 gpm (when new) radiator that flowed 10 gpm when first tested only flow
15 gpm after spending the night in the boil out vat in the caustic. A quick
check at the local radiator shop might give you a good idea of what condition your
radiator is actually in. Just a thought.

[JJorgensen52]

Originally Posted by Stocker

Sounds as though your clutch fan is the right size, fits in the shroud like it should, and is working properly. One thing is odd though, you said it doesn't pull as much air than your old 4-blade fixed fan. If it gets hot enough for the clutch to engage, it should pull more air, not less, even at idle. If you get any possible radiator problems fixed and still don't think your fan is moving enough air, try switching to a 7-blade. That was OEM on mine with factory A/C, and overheating has never been a problem.

I'm thinking this may have to do with the fact that only the lower part of the radiator core is getting hot - my suspicion is that the clutch isn't getting hot enough (due the radiator not heating up) to actually engage the fan.

I am going to try the vinegar trick first, and if that doesn't make the difference I'm going to start looking for a local radiator shop.

Thanks for the advice, everyone!

[hamjet]

Am I sounding like a dummy or is his fan running the wrong way. engines run counter clockwise right? the one he ordered says clockwise rotation. Boy I hope I read right...

[mechanicalman]

Originally Posted by hamjet

Am I sounding like a dummy or is his fan running the wrong way. engines run counter clockwise right? the one he ordered says clockwise rotation. Boy I hope I read right...

Most chevy's run clockwise, although I saw a Kriss-Kraft boat with tandem Chevy 350s one ran clockwise and the other ran counter-clock wise. It used a different distributor, cam, and had a 2-gear set-up running the cam on the counter one and a regular timing chain on the other one.

But you bring up a good point. Chevy's run a counter-clockwise fan setup on the serpentine belts and the wrong fan blade or clutch could prove problematic. But he has checked airflow so I think he knows what direction the air is blowing so the fan is probably the right one, however he could still have the wrong fan clutch.

[hamjet]

I just googled sbc rotation and if youre facing the engine its clockwise, but I'm in the truck cranking it and its ccw. I assumed thats how you look at things, from the seat, like left side of the truck, left fender, but when talking rotation I guess its different...

[mechanicalman]

Originally Posted by hamjet

I just googled sbc rotation and if youre facing the engine its clockwise, but I'm in the truck cranking it and its ccw. I assumed thats how you look at things, from the seat, like left side of the truck, left fender, but when talking rotation I guess its different...

Don't feel bad, this can be confusing. The driver side is considered the Left side, and the passenger side the right. However when dealing with the engine, you stand in front of it and look the other way.

Once something is messed up like that, it doesn't seem like it can be corrected. I guess it depends on how you look at it! LOL

Pun intended

[davepl]

They all turn the right way (clockwise), though I don't know why. Do RHD cars turn the other way? If not, there can't be any good technical reason.

I've made myself look kinda dumb when I didn't know that Ford numbers their cylinders different than Chevrolet.

FWIW, my big block has a 180F thermostat. With an infra-red temp gun the thermostat housing sits at 182 all day long. Doesn't change at idle. And this was on a warm day as well.

So, stock fan and clutch, stock rad, stock shroud, stock water pump. If all of those are in correct working order, it'll cool fine (unless the engine is radical). Unless you've got a 572 in there do not fall prey to the "add expensive aluminum and billet parts until I find the actual problem" approach.

Make a note of what your initial timing is as well. If it's retarded it'll run warmer, and may only be noticeable at idle.

[JJorgensen52]

Originally Posted by davepl

Make a note of what your initial timing is as well. If it's retarded it'll run warmer, and may only be noticeable at idle.

So what qualifies as retarded? I've heard a half dozen numbers - for me, I almost always start at 6* base advance and bump it up to around 10* if the engine is happy with that. This truck was set to 12* and it was pinging pretty badly, so I backed it down to about 6* and it's much happier.

That said, I made no change to anything except the fan itself.

[davepl]

Timing sounds right; 6-10 should be OK. If it were at part throttle I'd check vacuum advance but sounds like it's only at idle.

Weird that only the bottom half of the rad gets hot. Are you sure it's not plugged and needs to be boiled out? Maybe it's been like that a long time, but didn't matter until the clutch fan relied on it for temp sensing.

Unless you had a fancy two-pass radiator I can't picture a scenario in which a factory rad wouldn't heat evenly. In fact it should be hotter at the top and cooler at the bottom by whatever temp drop (maybe 30-60 degrees) that your rad can manage.

[brown7373]

When a radiator gets plugged, it is usually because all the sediment and other crud settles to the bottom and plugs the lower tubes. The fact that yours is hot at the bottom and not the top, makes me wonder if someone put something in the system that floated and clogged the top. Will silicone float?

[JJorgensen52]

Originally Posted by brown7373

When a radiator gets plugged, it is usually because all the sediment and other crud settles to the bottom and plugs the lower tubes. The fact that yours is hot at the bottom and not the top, makes me wonder if someone put something in the system that floated and clogged the top. Will silicone float?

I believe so, yes.

Either way, I've driven it about 50 miles today with close to 2 gallons of high concentration vinegar in the system, and I've noticed a definite increase in the size of the area on the core that's hot. The coolant is also completely opaque now, where it was pretty clear before. So seems to be working.

[dirtyjim]

I've tried the quick fix flushes on radiators and only found them good if they are used along with a yearly coolant flush and replacement. usually by the time the radiator is clogged enough to make it run hot it needs to have the tanks pulled and rodded out.
I've also had several clutch fans that were defective right out of the box, the last one was a $300+ land rover unit that had to be sent back to the uk before I could get credit on it

[JJorgensen52]

I think I've found the root cause of this problem, and it was neither the radiator nor the clutch fan.

Vacuum advance diaphragm failed

Anyways, replaced the advance can, and after a few days of vinegar in the system happy to report it's rock steady at the bottom of the green, just like I would expect it to be