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Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go hereXJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.
So like every other jeep owner...my 01 temp climbs above 210 in traffic in summer and if I turn the AC on (when I had AC)..the temps would be well above 210 even when the aux fan turns on. DISCLAIMER...I have a 4.7ish stroker with a big cam and 27 pph injectors so I know it will run hotter. I have done all the usual...new 3 row csf radiator hi vol FlowKooler water pump hi vol 180 t-stat with 2 or 3 1/8 bleed holes drilled into case...Napa 232710 fan clutch...aux tranny cooler plumbed in correctly..(thats another thread)...and I have wired in the fan with an override so I don't have to wait until 223deg till it kicks in. Background...in NOT SUMMER when ambient temps are 70 or less I have no cooling issues whatever and in winter I need to throw a 195 in there to keep temps high enough for Northeast winters but when the temps are 80 or higher I cannot keep the coolant temp below 210 in around town or stuck in traffic driving with the clutch fan only. When I did have AC I could not keep the temps below 210 when the ac and the fan were running in traffic I have not calibrated with an infrared thermometer but have thrown the sensor in a pot of boiling water and then read the resistance with a quality fluke meter....dead center factory specs...then I dial those readings into a decade box and plug into the coolant sensors harness ...reads a hair above 210...close enough for govt work. So I can assume the sensor reads correct....Per my obd 2 readings when the aux fan kicks on...223-225 ..again close enough to trust accuracy So driving around town clutch fan only temps steadily climb to 210-220...turn on the aux fan and within minutes....down to 182-185....t-stat rating...therefore the aux fan must be pretty damn good. I figured I need a better mechanical fan....not so easy...I tried a 15 inch flex-a-lite race fan...WILL NOT FIT inside of the stock shroud without modification to the fan or shroud....another project maybe...the Flex-a-lite thin 12 elec fan is on backorder for months...so not an option. So my great idea....I had a spare stock aux fan from my old 92...but it was the later 10 blade model so I figured I could use that instead of the mechanical fan...2 aux fans must be great. Problem was I could not find an easy way to power it (20+ amp startup) so I bought an adjustable fan controller at Advance and hooked it up...not too hard an hour or 2 ...I modified the stock fan with some aluminum angle from home depot because the "feet " in the mechanical fan shroud were wider than the aux fan "feet" by 3 inches... less than an hour and I was able to mount the aux fan solidly where the mechanical shroud used to bolt...just had to redrill 2 mount holes in the radiator bracket to match the fan mount holes. I had removed the clutch and fan and just secured the pulley with extra washers...they came really close to the fan...next time I will shorten the studs a hair..better clearance...I had the new "primary "fan adjusted to kick on at 190...SADLY...it could not handle the heat...it turned on and worked properly but "primary" elec only shot up to 210-220 faster than with the mechanical fan...and with both fans running I could barely keep below 210...I cant explain why it doesn't work as expected since the aux fan cools so much better than the mechanical...It might have been since the pri elec was an old fan it might not have worked so well but it was much worse than expected. I might try it again in the spring with the flex-a-lite fan in place of the stock elec...or put the flex-a-lite in place of the mechanical fan again...just very surprised I ran so hot on 2 electric when the standard aux fan brings my temps down so quickly.. The last picture shows the new PRIMARY elec installed in the old radiator for testing purposes...you are looking from the engine compartment side...Oh-yea...at highway speeds in summer 85+ I still run 195 with mech fan only...drops down to 190 if I turn on the aux...tranny fluid makes a good bit of heat to get rid of....hope this helps someone or opens up new ideas
pics of wires and fans make no sense? if you are overheating its because xj's have a sm radiator and crap cooling system I live in the Aussie Outback where it is hot all year long the xj suffers but if your cooling system is tip top condition then you can survive temps when did you last flush your block out?
Block was cleaned and flushed at machine shop last fall in prep for my stroker rebuild. All other cooling parts Are new. Many jeeps have cooling issues...how do you make it down there. Does surviving mean always between 210 and 220 . There should be a better way
My thoughts are to replace the clutchfan with a solid mechanical fan that doesn't slip. I'd have to actually cut one open, but there must be a way of pinning a clutchfan by drilling a hole thru the viscous clutch and making it solid. I did this on one of my Chevy trucks because I was a cheap bastard!. After draining the fluid, I put a 1/4" bolt and nut thru it. It helped considerably because it had 6 blades and the normal mechanical only had 4.
Ive had one apart by accident and there is not a whole lot to secure firmly around the shaft.. I tried to spin and lock the control valve at the end of the temp spring on an old clutch and it didnt seem to work any better... When I shut the engine off the fan stops turning just about instantly so I dont know how much better it can get...problem is there is no way to tell how much slippage the clutch gives it. 2ndly I dont know how many rpm's the fan can take without flying apart if it was truly a direct drive. Thus the Flex a lite race fan rated for 8000. Need to lop off about 1/2 to 3/4 inch off the tip, keep it rounded and balanced. The blades on the race fan are solid steel so a little difficult to work with by hand tools
I thought there was a spring or something you could reverse on the fan clutch to lock it on... maybe I'm wrong on that.
From the pictures I'd say, try a new radiator cap - Mopar if possible.
I had the same bullcrap... overheating in 90-100degree temps like we had for a few weeks this summer here in the Northeast. Same conditions - idling with the A/C on. New mopar t-stat, new fan clutch, flushed and clean perfectly mixed coolant, new e-fan, all that.
My old cap looked and felt OK, but I threw a new Mopar cap on and boom - never happened since.... Your cap looks less than new, so I'd replace it just to be sure.
Also, the mechanical fan moves far more air than the electric one does. I'd be careful with deleting the mechanical fan for an electric personally, but a better electrical fan might be better than the stock aux one. It does seem that folks seem pretty certain a mechanical fan is stronger just in general.
My XJ has never overheated idling in tropical temperatures, but it does get heat soak.
You can trim fan blades easily with a Dremel and cut-off wheel if you're handy. Just be sure to file them down afterwards or they are like knife blades! Bad enough to get hit by a blade, but not with a knife edge.
Maybe we could fill the drained clutch with epoxy? They say a solid fan can pull around 15 hp off an engine. IDK. It is turning faster than the crank because of the difference in pulley diameters.
Just a fyi...those fan controllers you have looks just like the ones I had in my truck and after 4 years one would not cut on and the other ne would cycle a lot. I ripped them all out and went back with the clutch fan. So keep a eye on them.
I removed the 2nd elec fan when I could not cool enough, all back to stock. I think I need to clarify a little...I consider constantly running between 215 and 225 is what I consider too hot. Its not technically overheating but it leaves me no cooling cushion to turn on the AC. The purpose of the t-stat is to modulate the coolant temp to approx what the t-stat is set for. The radiator system SHOULD be able to remove enough heat to allow the tstat to do its job. On mine and most from what I read, the radiator cannot cool enough and therefore the t-stat is wide open most of the summer If I had ac on it would soon drive past the 225 mark and the only option was to turn off the ac. I have had 2 jeeps in the past 20 years ..10 years each ran them for over 275K and stroked them out...they all behaved similarly. I don't see what a new cap would do if im not dumping coolant into the overflow bottle The level rises a little when hot but the cap holds the coolant in the radiator For the people in hot climates...what does yours run at in traffic
I removed the 2nd elec fan when I could not cool enough, all back to stock. I think I need to clarify a little...I consider constantly running between 215 and 225 is what I consider too hot. Its not technically overheating but it leaves me no cooling cushion to turn on the AC. The purpose of the t-stat is to modulate the coolant temp to approx what the t-stat is set for. The radiator system SHOULD be able to remove enough heat to allow the tstat to do its job. On mine and most from what I read, the radiator cannot cool enough and therefore the t-stat is wide open most of the summer If I had ac on it would soon drive past the 225 mark and the only option was to turn off the ac. I have had 2 jeeps in the past 20 years ..10 years each ran them for over 275K and stroked them out...they all behaved similarly. I don't see what a new cap would do if im not dumping coolant into the overflow bottle The level rises a little when hot but the cap holds the coolant in the radiator For the people in hot climates...what does yours run at in traffic
Both my 96 and 98 are running right at t-stat temps here in central Florida. It's been in the mid 90's for an extended period. I run the A/C and it brings the electric fans online keeping both Jeeps comfortably below 210. Both are completely stock. On the 96 I had a compressor changed and the goofballs at the shop broke my plastic mechanical fan shroud. My temps went up. Replacing the shroud brought them back down. That shroud is uber important to concentrating the airflow through the radiator to minimize temp increases. I'm running 195° t-stats in both Jeeps.
I remember years ago I had a car in south Florida and removed the t-stat thinking I really didn't need it. But, the car overheated because the coolant didn't stay in the radiator long enough to be cooled. It just kept circulating through the engine picking up heat until it went into overheat. Reinstalling the t-stat restored normal cooling system function.
Funny how the cooling system is designed with a whole bunch of parts that all perform a necessary step in cooling and breaking or screwing around with those parts can have a negative impact. I always thought the engineers were required to put in a bunch of expensive unnecessary parts.
The thermostat's one and only function is to maintain it's set temperature and not let the cooling system get below that temperature. It does that by closing if temperature drops and opening if it gets back up to set temp. At set temp, it is wide open and can't reduce temp above that. It also acts as a restrictor so coolant doesn't flow too quickly thru the radiator to give it time for heat transfer.
Back in my younger days, I got involved with dirt track racing. Nobody ran a thermostat and there were a lot of overheating problems. We took a thermostat and took the center out of it, put that in and stopped the overheating just by using a flow restrictor.
09-14-2020, 04:35 PM
Looked like a GREAT idea on paper
