Shouldn't the fan clutch on a 6.9 pretty much "freewheel" when the engine is cold? Compared to others I've seen mine seems really stiff - like it is all most fully engaged all the time.

Above 2000 RPMs or so the fan roars so loud that I can barely hear any other engine sounds. My temp stays down - needle hardly ever gets over 1/3 of the way from the C mark and pretty much never goes above the halfway mark.

Seems to me that the fan clutch should be mostly disengaged unless/until the temp gets above the halfway mark and THEN it should engage progressively more as the temp goes up from there. That's pretty much how the fan clutch works on every other rig I've ever checked.

Does the fan clutch on these motors work differently? Does it sound like there is something wrong with mine. I'd sure love to reduce the roaring at speed......

 

they are not completely freewheelin when stone cold,due to the silicone grease they use.once they start spinning they will eventually freewheel until hot

 

Mine works like that, which is how the International rental trucks I've used worked. I'm just surprised at the all on or all off action. I thought it would be a gradual transition. I'm just glad to hear it working. I just turn up the CD player to the Seismic level.

 

Well, I didn't mean completely freewheeling - that's why I said "pretty much" freewheeling.

Others I've laid hands on could be turned fairly easily. You could feel the resistance when turning it slow, and if you tried turn it faster the resistance would increase - up to a point.

The one on my truck is stiff enough that you can almost turn the engine with it - in fact, if the glow plugs were out I'm SURE you could turn the engine with it. Just seems like it is stiffer than it should be. The clutch can't be allowing much slippage the way it is.

I've always understood that at higher RPMs they are supposed to slip a LOT as long as the air through the radiator is fairly cool - to slow the fan speed and save fuel. The idea being that if the RPMs are up, you're probably movng fast enough for forward motion to push enough air through the radiator to take care of most of the cooling needs. If not, then that is what the heat sensing part of the clutch is for. As it heats up - due to the air through the radiator being too hot - the clutch will slip less pulling more air through the radiator. If/when it cools back down, then the clutch should start slipping more again.

The howling noise mine makes sounds just about like other rigs I've heard where the fan clutch is completely locked up and turning the fan full speed all the time......

Are you guys saying this sounds NORMAL?

 

If you cut the air filter housing completely off around the air filter I’m sure the noise from the intake will drowned out the fan and you can sell the radio because you can’t here that either! I didn’t quite go around but I cut a big chunk out (about 10”) so I could add a larger feeding tube – man. I’m now looking for a air filter housing for a 7.3 N/A Van if anyone has one - LOL

 

i would say that is not right.you should not be able to almost turn over your eng. w/ fan clutch! might be time for a new fan clutch.

 

LOL! THAT loud, huh?!?

Hope I don't run into the same problem when I do my dual ram-air......

 

Yeah, that's kinda what I was thinkin' too. Every one I've ever seen go out before would either lock up solid, or if it turned you could feel it sorta' "grind", or slip-then-catch, or wobble, or something. This one turns really smooth, just really stiff. That's why I was unsure enough to ask the question.

Guess I'll check the one on my spare engine and if it seems better, I'll swap that too. Pretty soon there isn't going to be enough left of my spare motor to bother trying to sell.....

 

Cheaper, the noise will be a little louder with the dual ram air but nothing to realy worry about...besides you'll be so impressed with the little extra kick when you on the freeway!

 

Yeah, yours sounds excessive to me. If you're hearing the howl driving down the road all the time that's not right. It should come in only when it heats up. Mine will come on and off several times pulling a pass.

 

Well, sounds like a fan clutch swap is in order then. Thanks for the feedback guys.

 

So as to not start a completely new thread, i just replaced my fan clutch and it still howls when i step on it and get near red line so much it drowns out the motor sound. The clutch was new not used and i get a decent amount of drag. Mine howls only at higher rpms and when hot or cold though...

 

The fans are supposed to be locked when cold until they have run up to 2000 RPM. They will then unlock until the air coming through the rad is HOT enough to require lockup and extra cooling.......

I would hazard a strong guess anyone with cooling fan lockup continually has either a bad clutch or a badly plugged radiator between the air cooling fins........ there is a strong requirement to keep the rad cooling fins clean, so clean them with compressed air then water/pressure wash at a distance, straight into the fins so as not to bend them..

 

Mine is locked right up all the time - I can see a couple of ball bearings poking out the back, wedged between the shaft and the housing. Still spins true through. I found a used one at a wrecker, but it seems stiff to me when I turn the shaft by hand (I haven't had time to try it in the truck yet).

I'd be curious to know how easily your old one turns by hand once you get it out.

Guy

 

What makes 'em unlock at 2k PRMs? Because mine doesn't....