Engine Fan Came Off!!

[OILBRNR]

Went offroad today, and was fooling around. Did a brake-torque type launch on loose dirt. I let off the throttle in second gear (had my fun throwing dirt and rocks) and heard a pop under the hood.



Upon inspection, the fan unscrewed, hit the radiator and one blade pierced the top of the fan shroud and stayed there!!



I threaded the fan back on, but didn't have anything to tighten it back up with so I took it easy the rest of the way home.



Has this happened to any of you? Was there a lock washer behind the vicous clutch?



thanks,

-dhl-

 

[B.G. Smith]

Fan

The manual does not show a lock washer. Torque is listed as 42 ft. lbs. It cautions to inspect the fan for loose blades, fatigue cracks, loose rivets etc. Also check the water pump to insure that it is ok. bg

 

[MidwestMotorman]

lucky you

Lucky you have a diesel and not a gas. That 2k launch in the diesel would be a 4500rpm launch in a gasser. Your fan would have gone through the hood then, and done lots more damage. I thought those fans had reverse thread so they would not unscrew while running?

 

[HEMI®Dart]

nathanbush & OILBRNR





The Fan clutches are left hand thread. As the engine runs, theoretically it should keep tightening itself. It shouldn't be able to uncrew itself.



The engine would have to run backwards or counter clockwise for the fan cluch to unscrew.



A cummins will run backwards. A few members have had this happen. Can't find the older the old threads about "My engine ran backwards" to get more info on how this happens. They've been "pruned"I guess.





OILBRNR , Make sure you fanblade(s) didn't get bent. If even one is bent trash it. It will be out of balance and destroy the vicous clutch in no time.



Did the engine sound funny or strange before the fan came off? Did it stall & restart itself?



Very Odd

 

[Bad340fish]

IF the fan was engaged and he were to let off real fast or something to cause the motor to slow down suddenly I could see it happening... still wierd though!

Clark

 

[OILBRNR]

No, the engine was running fine. I was on my way from Phoenix to Flagstaff, and stopped in an area that I do Quail hunting now and then. Let the dogs out to do their thing, and shut the engine down normally. It was in the high 90's, and I suspect that when I started it back up and pulled my stunt, the viscous coupling was rather thick and or positive. The iniertia upon let up of power just spun that fan right off. Had the coupling been less, I think the fan would have just free wheeled. It is a fairly heavy assembly.



The visual runout of the blades looks OK as viewed from above, and the radiator also looks OK except for a few small indentions. The shroud now has a nice hole in it on the drivers side top. I figure I can epoxy it back down, as a new shroud is probably mucho $$$.



Anyway, it was a strange occurance.

 

[HEMI®Dart]

"It was in the high 90's, and I suspect that when I started it back up and pulled my stunt, the viscous coupling was rather thick and or positive. The iniertia upon let up of power just spun that fan right off. "



OILBRNR, Good Call, I'll bet thats what happened

 

[MidwestMotorman]

curious

Just curious how many out there might have a loose fan as well. Normally these fans are so tight that you are afraid of breaking the water pump getting it off.



Maybe the fan was not torqued right to begin with? Or was left loose my someone who had removed it for service work?



This thread makes me a little nervous, I think I will check it this morning.

 

[chuck3]

Fan off

A friend of mine had that happen to him about a month ago! But he had a front end crash and had some work done on the radiator area, so we think it could have been caused by someone that performed the work?

 

[SmokinJoe]

Originally posted by OILBRNR

Was there a lock washer behind the vicous clutch?

No lock washer. FWIW I am running fanless. I hardly ever run loaded and I never go slower than 35 mph. When in city traffic I just turn off the AC at lights. It still takes some time for the temp to go a little over 190. Sounds like your clutch may be bad or had wrong fluid put in it. If you run fanless and get a LOT more mpg you have a junk clutch.

 

[Bob Cochran]

Fanless in Phoenix is not an option!!!!! Whole lots of problems if you do. It is a dry heat though except now it is our monsoon!

 

[HEMI®Dart]

Smokin Joe,



Taking my fan off was easily one of the best mods I've ever done. More hp & torque, much quieter engine, idle rpm will increase by about 50 rpm, throttle more responsive, mileage will increase about 1-2 mpg. I can't wait to pull it again this fall. NO change in the coolent temp what so ever. Even in 80º outside temps. I need to block 90% of the radiator (outside temp 40º and lower) to build any heat into the cooling system (190º) around town or highway.





For some reason the A/C will not work with the fan off in a 12 Valve. Even at 70 mph, nothin but hot air. Put the fan back on, I get ice cold air @ idle. I think is something to do the the condenser & head pressure.

 

[WestTN]

engine fan

If the RPM's dropped quite a bit when you dropped the clutch then the fan would briefly be running faster than the engine. Under those conditions it could possibly unscrew itself if it wasn't tight to begin with.

 

[GTX]

Broken Blade

My father's 96 has 104k on it and it was just in to get the radiator replaced because the tanks were leaking. They found one of the blades cracked half way thru so the fan was replaced also. He had the shop replace the thermostat also and they found it was stuck open by a piece of rubber in it. They could not find where it came from, it was different rubber than the hose's.

 

[gitchesum]

Re: Broken Blade

Originally posted by GTX

My father's 96 has 104k on it and it was just in to get the radiator replaced because the tanks were leaking. They found one of the blades cracked half way thru so the fan was replaced also. He had the shop replace the thermostat also and they found it was stuck open by a piece of rubber in it. They could not find where it came from, it was different rubber than the hose's.

It was probably the rubber around the thermostat. When I replaced mine, the rubber was completely gone. The bottom of the new thermostat was lined with rubber, real thin strip about 5/8" wide.

 

[Mopar-muscle]

just an FYI , the fan is NOT connected to the water pump on the cummins , its just an idler if you will , the water pump is off to the pass side of the block .

 

[GTX]

Thanks gitchesum but,

It was probably the rubber around the thermostat. When I replaced mine, the rubber was completely gone. The bottom of the new thermostat was lined with rubber, real thin strip about 5/8" wide.





The rubber is still there and in one piece. Had to come from some where else.