Electric fan cfm Q (I'm almost afraid to ask!)

Hi all,
I did a search and found an entertaining, though heated exchange;
:explosion
http://www.naxja.org/forum/showthread.php?t=12051&highlight=stock+fan+cfm
My question is, does anyone know what the newer-style electric fan has for cfm rating?
I have been looking to upgrade my older style to the 10 blade, but they are hard to find and pricey. I am wondering if I would be better off with the Perma-cool 14", 2950cfm, and fab it to fit the stock shroud.
Thanks for any advice,
Todd

I guess I'll walk into this mine field. Let me ask are you having cooling problems - yes or no? If yes then you need to look at other things first, If no then just do routine maintenance.

I see on your profile you have a 91 XJ. Have you done normal maintenance stuff? When was the last time you changed:
* Radiator
* Upper and lower radiator hoses
* heater hoses
* Thermostat
* Radiator cap
* Fan clutch for mechanical Fan
* Fan belt
* coolant

My guess is most of it could still be stock. Before we head down the modified fan route lets make sure the system is working good.

I personally change my hoses and fan belts every 4 years regardless of mileage. I did them in 2000 and just did them again 2 weeks ago. This time I picked up the radiator hoses at the dealer, figure on $20 each but they are very nice! The lower has the spring inside to prevent collapse. Also both upper and lower came with the anti-chafe installed, I would recommend everyone use the dealer hoses and they were within a buck of what autozone wanted for their best hoses, the Goodyear ones.

In high school my dad maintained our cars "on condition" instead of doing preventive maintenance. In college we were at a relatives house, the 69 camero has a bad upper hose, he cut off the last inch and told me to drive it. The next town with a parts store was 35 miles away. I did not want to break down so I changed the hose at the relatives house once I found one in the town of 1700 people. I am big on making sure the cooling system is only down when I want it to me... not having it influence my schedule.

If you are running hot change out the mechanical fan clutch, there is NO good way to test them. I replaced the factory one in 2000 and replaced it again 2 weeks ago. The consensus on here is the clutch may last 5 years so while I had the radiator out it was no more effort. I also installed a new Mopar 195F thermostat.

My guess is you still have the factory radiator. I installed a GDI 4 years ago and been adding a pint to quart every 1000-3000 miles. I installed a new Modine and it holding fine. I had a leak in the GDI where the tubes attach to the end plates but was not to leave anything on the ground. I could see the white residue when I had the mechanical fan shroud pushed out of the way and was real easy to see when I pulled it out of the XJ.

With the radiator out this would be an ideal time to replace ANYTHING on the front of the engine - water pump, harmonic balancer, etc. I did my water pump 2 years ago since it had 135,000 on it and the balanacer was done at the garage 4 years ago when it began to walk toward the radiator and caused the fan belt to break.

If you change the belt spin all the accessories to see if they turn smoothly. I highly recommend you change the idle pulley by the AC compressor. Also install the belt using the Kriket II belt tension gauge. I posted the NAPA P/N stuff in the past week. Made installing a new belt easy work, no guessing on the tension!

When you refill with coolant use distilled water instead of tap and pull the temp sensor out of the head, if you have one, when you are filling to get the air out of the block.

Like I said if you are running just fine then let the sleeping dog lay but if you are running warm time to do cooling system maintenance BEFORE you start a science experiment with the electric fans.

Hi Martin,
Hey, thanks for the great info! I appreciate it.
As for my situation, I already made the mistake of replacing my clutch fan with a flex-a-lite 110(see other post). I think I am heading in the right direction for an electric replacement there, much higher cfm-rating. I'm really only interested now in the auxiliary side, and whether I should spend much time looking for the newer 1997 and up style, or do an after-market. My current aux. fan is in rough shape, that's my reason for wanting to change it out. I have the GDI 3-row, thankfully no leaks! I'm thinking if anything my water pump may be my weak link, 140K on it. I have heard Hesco is the way to go, but haven't done much research on it. I plan on looking for your post with the belt info, sounds helpful.
Thanks again,
Todd

FYI that 'beefed-up' fan is in more than the 97+ Cherokees. I think it may have made an appearance in '95 but I know it's in at least some '96s (mine included). I did an unscientific back of the hand test on mine and it certainly seems to pull a lot more air than my old 89 fan did.

Well if your electric fan is on it's last legs that a different story. I would look into the newer style fan if that was the case. I understand is it a drop in part/no modifications required. I have never been able to find the CFM rating for the electric fan but with the more blades it would seem it woudl move more air. I think your fan is controlled by the engine computer so it will only run when needed. On my Renix 88 XJ the fan only comes on when the AC compressor is engaged OR when the temp sensor in the cold tank of the radiator measures 190F the the fan is turned on.

I did install a Hesco waterpump on my 88 XJ two years ago but it does have a high price. I liked the look of the impeller. It looks like very similar to the centrifical compressor section of a turboshaft engine. The stock impeller is just a stamping. I went with the Hesco more because it said they discovered 6 more HP and 2 more Ft-lbs of torque. I am into freeing up HP!!

I did not go with the Hesco high flow thermostat or the high flow thermostat housing. Hesco is located in B'ham, al which is 2 hours from me. I went to their facility and picked up the water pump. They were nice and showed me around their shop. The told me they make the MPI kit for the carborated 4.2 wranglers.

I highly recommend you get the water pump gasket at the dealer. It looks better than the fel pro gasket and has the RTV pre applied. I installed it dry on my engine. In general I think applying RTV to a gasket is not a good idea but if Chrysler thinks it needs to be on there then what is applied to the gasket is the "correct" amount. The gasket material should take up any inperfections in the mating surfaces, I have seen gaskets way too much RTV.

If you buy the mopar thermostat it also comes with a gasket with RTV pre applied. Since air being trapped in the engine is a known problem with the 4.0 you need a thermostat with the vent hole and for some reason the Mopar the only one that has that hole, not even the stant has the vent hole.