Going back to a mechanical cooling fan

Whelp...it was good while it lasted. I built my Jeep with the Contour electric fan for cooling. It worked okay, although my Jeep always seemed to run a little hot ~200. But then today happened. I was about an hour from home with the whole family in the Jeep with me when my wife smelled something was burning. We were stopped in a parking lot at the time and I didn't think anything of it since it was so hot out, until we pulled out and went down the road apiece and I started smelling it too, then I noticed the temp gauge slowly going up past 200 then 210...and seeing my volt gauge drop from around 12.5-13 to 12. I pull over, turn it off and pop the hood. I check the fuses for the fan which are mounted on the fan shroud itself as part of the controller and this is what I find...



After looking around a bit longer I figured out that one of the fan motors seized and I think that's what caused the meltdown. Mind you, this is the 30 amp fuse that came with the controller, it should have tripped before it got to melt down condition (in my humble opinion). Once I figured out the other fan was okay I unplugged the bad fan, and used a fuse from the heater motor since I had no spare fuse of that size. However, I also found that I had to change out the relay for the fan...luckily I ran my headlights through a relay so I unplugged one of those and used it for the remaining cooling fan.

I limped home with my temp hovering around 210 since 50% of my cooling fan capacity was now gone. I'm thankful it was daylight, but it was also ~90* today so bad things could have been much worse.

So...I ordered an Omix fan shroud and I'm putting back on my mechanical fan that came with the Jeep, one of those flex fans. My question is, do the flex fans require a fan clutch also? It only came with the fan and a spacer, no clutch.

 

The other part of this story is that I was scheduled to go with the Jeep club to North Carolina on a wheeling trip today, would have been 3 hours from home. I think mechanical is the way to go now....it's hard to break those, and with a 360 I won't miss any HP.

 

You should be just fine with only the fan. My understanding of a flex fan is they flatten out at speed and return to normal shape at slower speed.

 

Which controller make were you using? Perhaps it needed one of the maxi size fuses not a regular fuse, too small to handle the task maybe.
I'm setting up a fan from a Focus and using the maxis. Now with that said, on my Son's '97 Continental, #2 fan seized and
toasted the wiring at the connector before tripping the fuse.

_Dan

 

I don't remember what brand it was...I installed it almost 6K miles ago (~4 years). That's exactly what happened to mine, seized fan motor, and the fuse is melted. Thankfully no wiring damage that I could tell.

I'll be more comfortable with a mechanical fan now. Just too much risk otherwise after this experience.

 

Use the fan from a full size jeep with a 360 and clutch..
should be a 7 blade fan...

For some reason I have just learned to trust stock set ups for temp, charging, ignition, etc...
millions were spent designing, should be good enough 99% of the time.

 

I'll echo rejeep's recommendation. 2 jeep's with V8's, 1 304 and 1 360 and both have stock 7 blade fans with fan clutches and factory shrouds. The 304 has never seen 200 degrees. The 360 has gotten to 210 a couple of times but it's been during the summertime here in Phoenix.

FWIW,
Mike

 

The more I read, the more I agree with you. Sounds like the flex fans just aren't all they're cracked up to be. My local pull a part is out of FSJ's, but I read where most any large Chevy/GM (trucks, Cadillac, etc.) has 7 blade fans of the same diameter and fit the water pump so I might pull one of those and buy a new thermal clutch at the FLAPS. Had to go with an aftermarket shroud...I hope it fits well.

 

Yeah, I would skip the flex fan. They are really noisy, and hazardous/dangerous. I have heard stories of the blades coming off. I have also cut myself on the sharp flex fan blade edges. And DID I MENTION THAT THEY ARE NOISY? Like a jet engine.

 

I went to Pull-A-Part and got a 7 blade fan, 18" diameter, off a '79 Cadillac ElDorado. Stopped at the FLAPS on the way home and got the Grand Wagoneer clutch...it fits the fan perfectly. Now I just have to hope that Omix has a good shroud that won't need any additional assistance to install and I should be golden. Shroud shows up Tuesday this week.

 

The simplest the best, for a Jeep... Omyx is not top level products. Why not just a belt and a fan? Of course I just have a Hurricane, so the temps is never over 170. But I don't have a hot climate. Wish you good luck ...

 

I have one of the Omix shrouds for my CJ-6. It's sitting in the basement. I suspect that the fan on my CJ-6 is not original, and it's too large in diameter for the Omix shroud. Otherwise, it fits ok and looks like decent quality.

 

I have the original fan on mine with the Omix shroud. The shroud is high quality. It's made of thick plastic, probably polyethylene. I did have to drill new mounting holes in the shroud for it to be more centered.

 

The Omix web site has the opening at 21"...my fan is 18" so I think it will fit. Glad to hear it's high quality. I'm okay with drilling new holes if necessary to center it, but I'm hoping mine will fit good out of the box. I haven't done anything funky like non-oem motor mounts, or higher than normal body pucks so I think it'll line up well.

 

I also have the same setup on one of my jeeps but only have one of the fans on auto/therm. One fan is all I ever need with my V6 but the other fan can be controlled manually from a flip switch on the dash for as needed.

rocmoc n AZ/Mexico

 

I've always been a big believer in a mechanical fan in a good shroud. If properly engineered, it will move way more air than any electric. As for flex fans, they may save a little gas but are counter productive if you run any rpms at slow speed. They do what they're designed for and flatten out when you need them the most. A clutch is a better deal but I just eat the mileage and run a straight rigid fan.

With a 21" shroud opening, I would go for a bigger fan. The one in my 3B is 19.25" and something close to that would work well for your situation.

 

Received the Omix fan shroud...what a pleasant surprise it was. The shroud looks to be very stout and trimmed well, not sloppy at all. The initial fit looks good, although I haven't actually bolted it down, the holes look to align very well to the radiator bolts. There is even a flat edge that faces the radiator where I could put some foam tape or something to help it get a tighter seal around the radiator. The opening is plenty big enough and I could go with a larger fan (the one shown is 18"), but I'll stick with what I bought so far and see how it works. If I need more later I know where to go.

 

Okay...to close out this thread...I installed the shroud, fan, and fan clutch today. I forgot how hard it is to stuff all that back into a CJ5 engine bay. The shroud didn't need any trimming at all and lined up to the radiator bolt holes perfectly. They seem to perform pretty well together, but not as good as I was expecting. Temp is still ~200 after a quick trip to the store with speeds between 45-55, outside temp is ~80. That's about where the electric fan kept it, if not a bit cooler. I did notice how my volt meter held up to ~14 without the fans running though.

I wonder if my temp running a bit high is because of the Warn 8274 winch in the front...does it block too much air?

Anyway, here's a pic showing the gap between the fan and shroud, it's about 2" at the top and about 1" at the bottom...so I could go with a slightly larger fan without having to re-align the body to the engine or trim the shroud. The fan blade pitch is 3.25" so it blows pretty well. I sealed up the shroud where it meets the radiator with some self-stick foam insulation tape.

All in all I'm glad I made the switch, its one less thing to worry about breaking down. I just need to see how it does after a days worth of wheeling, then I'll decide if I need a larger fan.

 

Check any used factory Jeep 7 blade fan very closely for cracks around the rivets that hold the blades to the fan arms.
Over the years I've seen a couple dozen fans that had cracks develop in the blades at the rivet points.
I've seen some that had come apart or come off.
The factory 7 blade fan pulls a lot of air.
Just a heads up.

 

When I find one I'll be glad to check it out...this one came out of a '79 Cadillac.