rhinoo Posted December 29, 2022 Share Posted December 29, 2022 Got a 98’ Rd688s with an e7-350 and the engine cooling fan seems to run too much. I own several semis and they all are air operated but this motor has a fan drive type fan on it. Im not sure if this is even correct or not? I assume it works off of a thermostat built in to front of the drive? I can turn it with engine off but has some resistance to it. It looks like it had been replaced recently. I can start it up at 20 degrees and it will be running wide open. Any help is appreciated. Quote Link to comment Share on other sites More sharing options...
BOBWhite Posted December 30, 2022 Share Posted December 30, 2022 That is a vicious fluid fan drive or fan clutch. Whenever you start cold the fan runs for a couple of seconds before the fluid can be pumped back to the reservoir and the fan disengages. There's really no way to control when the kick on and you kinda just have to live with it. All Macks from the 80s and 90s that Ive seen use this type of clutch. Been meaning to ask has anyone ever replaced the vicious clutch for an air operated one? To me that would be a nice upgrade. 2 Quote Link to comment Share on other sites More sharing options...
Onyx610 Posted December 30, 2022 Share Posted December 30, 2022 (edited) There’s a little coiled bi metallic strip on front and in the center that expands at a specific temp and opens a valve. Which lets the viscous fluid in and locks up the fan. When cooling has been achieved to specific temp it contracts and fluid drains back as the valve closes. What temp is fan coming on at and how often? Edited December 30, 2022 by Onyx610 Quote Link to comment Share on other sites More sharing options...
Mark T Posted December 30, 2022 Share Posted December 30, 2022 Isn't there something about the position they're stored in ? Like if it was stored lying down they don't work. Quote Link to comment Share on other sites More sharing options...
Onyx610 Posted December 30, 2022 Share Posted December 30, 2022 1 minute ago, Mark T said: Isn't there something about the position they're stored in ? Like if it was stored lying down they don't work. I’ve heard things like that also but can’t verify. Kind of like leaving batteries on concrete floor drains them? Quote Link to comment Share on other sites More sharing options...
Mark T Posted December 30, 2022 Share Posted December 30, 2022 It's a thing. There's a way they're supposed to be stored ( like mounted on the truck ) after so long the fluid doesn't move in them so they turn free in some of them. Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted December 30, 2022 Share Posted December 30, 2022 no one gives a damn how they sit on the shelf. at the parts houses.. . When they are on the engine, they go into service.. centrifugal force and heat tells them what to do... am I wrong Mark?? jojo 1 1 Quote Link to comment Share on other sites More sharing options...
Popular Post rhinoo Posted December 30, 2022 Author Popular Post Share Posted December 30, 2022 26 minutes ago, Onyx610 said: There’s a little coiled bi metallic strip on front and in the center that expands at a specific temp and opens a valve. Which lets the viscous fluid in and locks up the fan. When cooling has been achieved to specific temp it contracts and fluid drains back as the valve closes. What temp is fan coming on at and how often? I felt the strip in the front like you are talking about. It seems to hardly ever shut off. Engine temp never gets over 180 in dead of summer. My auto mechanics teacher back in the late 90’s taught us to test those fan drives by holding on to the fan blade while someone started the vehicle and as long as you can hold it, it was good. I asked what if it wasn’t good and he said you gotta be quick…lol. don’t think I’m gonna be attempting that trick on this big fan. Gotta run to Mack in morning, guess I might price a new one. 3 Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted December 30, 2022 Share Posted December 30, 2022 nice testing procedure.. what if you took a long grill lighter and warmed up the coil and pulled on the fan blade at the same time to see if it got tighter.. of course there wont be any centrifigul force.. Im just sayin, and messin too.. I think they are still under $100.00.. Good luck, jojo Quote Link to comment Share on other sites More sharing options...
Mark T Posted December 30, 2022 Share Posted December 30, 2022 15 minutes ago, Joey Mack said: no one gives a damn how they sit on the shelf. at the parts houses.. . When they are on the engine, they go into service.. centrifugal force and heat tells them what to do... am I wrong Mark?? jojo There's something about them being stored. After so long they don't work or take forever to start working correctly. Like those bear ones you gotta hot wire and let it run at a certain RPM until it frees up Quote Link to comment Share on other sites More sharing options...
Onyx610 Posted December 30, 2022 Share Posted December 30, 2022 Usually when they arnt good they won’t lock up and will have hardly any resistance. However I think you’re making the right move getting a new one. Quote Link to comment Share on other sites More sharing options...
Mark T Posted December 30, 2022 Share Posted December 30, 2022 Airflow through the radiator is another thing that has to be like it should 2 Quote Link to comment Share on other sites More sharing options...
Onyx610 Posted December 30, 2022 Share Posted December 30, 2022 I’ve also heard to take a roll of newspaper and stick into the fan and see if it stops. Don’t have the balls to do that in the case that it isn’t haha 1 Quote Link to comment Share on other sites More sharing options...
Mark T Posted December 30, 2022 Share Posted December 30, 2022 Baby 🤣 1 Quote Link to comment Share on other sites More sharing options...
Popular Post Joey Mack Posted December 30, 2022 Popular Post Share Posted December 30, 2022 I dont blame you Onyx for not doing that... My dumbass has had his knuckles shaved too many times.. My smartass comments are usually based on my dumbass mistakes.... Jojo 2 2 Quote Link to comment Share on other sites More sharing options...
Mark T Posted December 30, 2022 Share Posted December 30, 2022 That shop teacher must have really cared about his students 2 Quote Link to comment Share on other sites More sharing options...
Onyx610 Posted December 30, 2022 Share Posted December 30, 2022 2 minutes ago, Mark T said: That shop teacher must have really cared about his students You were pry the teacher Quote Link to comment Share on other sites More sharing options...
Mark T Posted December 30, 2022 Share Posted December 30, 2022 Seriously, who tells a kid to try that ? Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted December 30, 2022 Share Posted December 30, 2022 A D-Bag... thats who... jojo 1 Quote Link to comment Share on other sites More sharing options...
Onyx610 Posted December 30, 2022 Share Posted December 30, 2022 Rihnoo before you condemn the fan clutch check the radiator for good flow like mark said and also coolant level. 1 Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted December 30, 2022 Share Posted December 30, 2022 Lets not forget belt tension and pulley condition.... Just trying to act smart here,,, Jojo 1 Quote Link to comment Share on other sites More sharing options...
Onyx610 Posted December 30, 2022 Share Posted December 30, 2022 1 minute ago, Mark T said: Seriously, who tells a kid to try that ? Yea that’s what I was thinking when I read that. Coming from a man that’s supposed to be teaching kids… Quote Link to comment Share on other sites More sharing options...
Onyx610 Posted December 30, 2022 Share Posted December 30, 2022 Ok rhinoo you got a small list and an easy one. Radiator, coolant level, pulley condition, and belt tension. 1 Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted December 30, 2022 Share Posted December 30, 2022 Yep... Quote Link to comment Share on other sites More sharing options...
Mark T Posted December 30, 2022 Share Posted December 30, 2022 That fan drive needs to be replaced. I went through 2 on an E9 once. Then the third one worked. Original failed and would no longer drive . Then replaced it....never came off full on , second one was the same way. Third one worked like a Swiss watch. And FYI an E9 with the fan stuck on ? real treat to try shift'n all day. Quote Link to comment Share on other sites More sharing options...
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