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Old 09-14-2018, 08:10 PM   #1
Mini-Skoolie
 
Join Date: Jul 2017
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DT466 Viscous Fan Question

There are a few threads discussing the Viscous Fan on the International DT466 in relation to diagnosing overheating problems.

But if you already know you need a new viscous fan, am I correct that driving with a non-functional viscous fan is not an issue unless your engine temp starts climbing to unsafe temps... in other words, as long as you keep the bus running in a safe temp range, it doesn't matter whether the fan is working or not??

Secondly, does anyone have first hand knowledge of how much it cost to replace the fan clutch? Anyone done it themselves? How labor intensive is it?
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Old 09-14-2018, 09:12 PM   #2
Bus Nut
 
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Year: 1954
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Chassis: old f500- new 2005 f-450
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generally speaking

if the radiator is out front and you are doing 35 mph or more, I would think you could squeak by with out a fan at all. slow up mountain grades, or stop and go traffic, you are going to need that fan. Depending how the fan is attached, you may need special tools to do the work. Many fans with these big single fastening nuts, the threads are backwards from most other nuts and bolts. figure an hour minimum charge. that is minimum. A lot of places that is $135 an hour

william
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Old 09-14-2018, 09:28 PM   #3
Bus Geek
 
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there are different DT-466s and different fan clutches.. the mechanical DT-466 used a stud mnount type clutch.. there are 4 or 6 bolts holding the fan clutch to the center hub and 6 bolts holding the fan to the clutch..



removing it.. there are several different ways to approach it.. I have a DT360 (mechanical).. and was able to remove my clutch by putting a piece of cardboard against the inside of the radiator to protect the radiator.. then I separated the fan blade from the clutch, removed the alternator, and separated the clutch from the hib... i was able to pull the fan back against the engine and slide the clutch out carefully...



if you have a DT-466E. you will have a hub mount clutch.. its a single large bolt in the center of the clutch, and its a REVERSE thread.. which means turn it to the RIGHT to LOOSEN it.. you'l need a fan clutch wrench to hold the pulley stopped and then a 2 INCH open end wrench and a little muscle to break that large nut free.. then remove as described before... separate the fan, yank the alternator and slide out the clutch...



I think the kit-masters reman clutches will be anywhere from 200-400 bucks depending on which you need.. you can call navistar dealer, give them last 8 of your VIN and tell them you need a new fan clutch.. dont have a cow when they give you a price.. just ask for the part number... then go shopping... that navistar part number will likely cross reference..



now.. do you need a fan? the answer is yes and no.. you are coprrect in that you can drive with a bad fan c.utch as long as you dont get that engine hot.. but if you happen to end up in a situation where its getting hot.. you need to be preapred to figure out how to cool it down.. run that DT-466 above 230 degrees a time or two and you''ll be replacing the cylinder liner seals.. (rebuilding the engine essentially)..


when the clutch was bad on my DT-360.. it still spun at minimum speed of 300-400 RPM all the time which moves some air.. at idle it ran cold.. in town it ran cold.. on the highway on a hot day.. (above 80 or so).. it would run up to 215 or so... saw it get close to 220 once...



if your clutch is so bad that you dont get minimum speed.. the fan barely spins.. then you will have more tendencies to over-heat under high RPM heavy Load or mountains or towing...



incidently since I replaced my clutch and adjusted the temp down on the new one.. I run up to 185 MAYBE 190 Max.. and I hear that fan roar and ive never seen anything close to 200... except when the air shutters stuck closed once this spring.. it went up to just above 200 before I got them open...then that fan roared to life to quickly cool it down.. and that was a hot day.. 90+
-Christopher
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Old 09-17-2018, 02:28 PM   #4
Mini-Skoolie
 
Join Date: Jul 2017
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So I drove the bus at night for cooler air temps... I drove half of my 800+ return trip home. I'm not driving the second half til later in the week. The engine temp stayed around 180 unless climbing, then could go up to about 200.

The transmission temp, however, would spike even on short, or gradual, grades, and then quickly come back down as soon as I was back up to speed The downhill side.

The fan spins easily by hand when the engine is off, so it seems that it likely does need to be replaced. But here's my question: it's my understanding that the tranny uses the radiator and the fan to cool off, same as the engine. But if the fan is not designed to kick on until around 210 degrees... Well I never saw the engine temp get that high. But the tranny temp would be approaching 300 on the climbs.

Will installing a new viscous fan clutch help in cooing the tranny, or is there something else I'm not yet considering?
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