Fan clutch

[hex0rz]

Alright, been a looooong time since I have had to diagnose a fan clutch. Can't remember how to tell if its operating properly...

[Mopar1973Man]

Alright, been a looooong time since I have had to diagnose a fan clutch. Can't remember how to tell if its operating properly...

When cold you should be capable of stopping the blade with a old radiator hose... When hot you should hear it lock up and sound like a turbo prop taking off...

http-~~-//www.youtube.com/watch?v=QeKndmCy_yk

[hex0rz]

When cold you should be capable of stopping the blade with a old radiator hose... When hot you should hear it lock up and sound like a turbo prop taking off...

http-~~-//www.youtube.com/watch?v=QeKndmCy_yk

I also read of it continuing to spin after the engine shuts off when up to operating temp? I think I will take a roll of newspaper to it instead of a solid piece of rubber. I don't want to damage anything if it is bad, lol.

[KATOOM]

When the engine is off..... If you grab a fan blade, you should be able to spin it but offer considerable resistance. Trying to spin it should result in free spinning no more than an inch or so on its own. It should also have zero play in all directions. If it feels like this then its probably just fine. The fan clutch doesn't FULLY engage until the clutch registers 205*. Thats means its plenty hot out or the engine is working hard. Its always partially engaged which is why the A/C works during idle but when the fan fully engages while driving, you'll hear it.

[hex0rz]

Are these fans viscous or centrifical? When truck is cold, fan will have resistance and not want to spin very much. Probably about as much as you described. Talked to a guy at O'reilly's and he described it like you did.So, I assume its in good condition then. Although, I never hear it roaring, ever. Thats why I figured it was bad, that it was not fully engaging. I don't have temp. problems though.

[dripley]

I hear mine mostly on cold start up which is normal until the fluid warms in the clutch(they are viscous). I do sometimes hear it when towing in warm weather, but for the most part it is silent. But when it comes on it is quite obvious. Turbo prop is an accurate description. Mine pretty well acts pretty much as Katoom describes it. There is no way I am sticking anything in there to stop the rotation like Mike can. Mine has never been like that. I am having an overcooling problem though, maybe that has something to do with it. It seems to work like it has since new.

[Mopar1973Man]

Dripley your fan might be locked solid too.As for cold free spin mine is so tight that I can pull the belt around 1/4 turn. But now start the truck drive 1 mile and then shut down and check again now it spins rather freely.I check to make sure it not locked solid with the hose test. Both the 96 and 02 behave the same way.

[dripley]

I know it is not locked solid because you can hear it when it engages. The noise is quite loud. It has been that way since new. Whether it engages less or more often than when new, I would be hard pressed to remember for sure. When I left for work this morning the fan was engaged and you could clearly hear it disengage about 3 minutes later. I have heard it come on a few times here in Iowa when it got into the 90's. Not often though.The FSM states if the fan free wheels more than 5 revolutions when spun by hand it needs to be replaced. This is with a COLD engine. I would be lucky if mine went 1" when spun. It seems there are many others like mine. Ther is another test for proper operation, it is a liitle to invloved to post. it is on pages 7-57 and 7-58.

[hex0rz]

The FSM states if the fan free wheels more than 5 revolutions when spun by hand it needs to be replaced. This is with a COLD engine. I would be lucky if mine went 1" when spun. It seems there are many others like mine. Ther is another test for proper operation, it is a liitle to invloved to post. it is on pages 7-57 and 7-58.

FSM? I have a Chiltons, wonder if it covers it...

[dripley]

Factory Service Manual. It is in the download section. Covers the truck hands down better than a Haynes or a Chiltons. I got a haynes but not with me.

[Mopar1973Man]

FSM? I have a Chiltons, wonder if it covers it...

Like this? http://forum.mopar1973man.com/downloads.php?do=cat&id=19

[hex0rz]

Nice! I'm gonna check it out!

[KATOOM]

I hear mine mostly on cold start up which is normal until the fluid warms in the clutch(they are viscous). I do sometimes hear it when towing in warm weather, but for the most part it is silent. But when it comes on it is quite obvious. Turbo prop is an accurate description. Mine pretty well acts pretty much as Katoom describes it. There is no way I am sticking anything in there to stop the rotation like Mike can. Mine has never been like that. I am having an overcooling problem though, maybe that has something to do with it. It seems to work like it has since new.

dripley, what kinda overcooling problems are you having? If your engine temp takes forever to climb or wont reach and maintain 190* then you may have a thermostat problem.

[dripley]

dripley, what kinda overcooling problems are you having? If your engine temp takes forever to climb or wont reach and maintain 190* then you may have a thermostat problem.

The same problem we discussed on CF. Wild swinging of temps. I am now on my 7th tstat in 5 years. The one that was working ok crapped out, so I bought another last night. Getting ready to test it this am.

[KATOOM]

The same problem we discussed on CF. Wild swinging of temps. I am now on my 7th tstat in 5 years. The one that was working ok crapped out, so I bought another last night. Getting ready to test it this am.

I just dont get what could be the reason why there is so many people having thermostat issues. There has to be a logical answer.

[Mopar1973Man]

:shrug:I change coolant and thermostats yearly and never seen a overheat nor underheat issue yet. This thermostat I got now is a bit low but not bad 185-195*F range still. I may wander a bit on cold days but seem very steady now with summer coming.

[dripley]

I installed a 190* from Car Quest this morning. The salesman could not tell who manufactured it. Made in the USA was stamped on it. Compared to the one I just took out, it was of much stouter construction. The old one did not have the jiggle pins in it and it worked in a range of 170 to 189 fluctuating constatly. The new got to near 185 before it fell of to 170 and fluctuated all the way to work. I exited the interstate and stopped at a light 30 seconds later and watched it fall to 165 from 180. This is how the old one worked until last week. The temps on it started running 155 to 175, but mostly in the lower range.There is definately something else going on here. I have had tstats fail open and the engine just runs cold, stuck closed and it runs hot. Never like what I am seeing now. When I am towing the temp is up maybe 4 or 5 degrees but still swings, although little slower.I could see the fan clutch affecting cooling if it is locked up, but I still hear mine come on and off. iIt is a very unmistakeable sound. But mine does not freewheel like Mikes. If i get a wild hair this pm I might just take the fan off and see what happens on the way home. I dont realy dont want to throw a $100+ part at it just to test it.

[KATOOM]

I dont care what anyone says..... That is NOT normal, and I agree with you there must be some underlying issue causing this besides chalking it up as poor thermostat construction. Maybe there's a air lock which is cycling the thermostat in and out of coolant causing the temp to swing. And I'm not sure why the thermostat you had did not have jiggle pins since I understand the jiggle pins are there to help stop air locks.

[hex0rz]

You guys sure my fan is a viscous clutch? I pulled it out last night and it had a coil on the front.You know what else I hate, the fact dodge did not think to make the fan shroud a 2-piece! What a PITA!

[KATOOM]

You guys sure my fan is a viscous clutch? I pulled it out last night and it had a coil on the front. You know what else I hate, the fact dodge did not think to make the fan shroud a 2-piece! What a PITA!

Yes, the fan clutch is viscous. The coil is the clutch's thermostat.