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overheating mishimoto rad and pump

whitrock

NAXJA Forum User
Location
dewey arizona
We just got a new to us 1995 xj 4.0 which the po had put on a mishimoto radiator, elec fans and water pump along with thermostat.
we had about 60 mile trip home with the jeep when about 40 miles down the road the heater control valve blew alll to. now we fixed that and got the jeep on home and ran it a bit around town then the thing overheated again in the driveway.
I pulled the plugs did a compression test not great but not the problem i dont thin, then i pulled the thermostat it seems to work and i pulled the mishimoto water pump an the tiny little thing just dont look like it would cool also the impeller im not sure it is running the right ; it turns counter clock but the impeller if it has a scoop action on it would be clockwise if it is to use the back side of the scoop then its right,, not sure on this.
anyway the long and short are these little elec fan .82 gallon alum rads an all just a gimmic or are they supposed to cool. the po thought he had done the world a great favor putting on the 1000 dollar worth of stuff. any help greatly appreciated.
thanks Whitrock. 1995 xj 4.0 automatic 4x4.:flame:
 
I have the mishimoto radiator. Stock pump, stock mopar OEM mechanical fan and aux electric fan. No issues with overheating. Lots of folks run all stock with a Spectra radiator with success.

No idea about the mishimoto water pump. Did you flush the system? If it is full of crud the radiator may be clogged now.
 
cal had an unresolvable issue with the Mishimoto radiator clogging. Apparently the passage ways are thinner than typical, and some kind of iron debris was accumulating. I think it happened to him at least twice, so he stopped using it.
 
Thanks all; i will roll it onto the driveway and flush it out good next. Got a stock water pump to put on but still in debate about a new radiator, might use the mishimoto but i want a stock fan so not sure how to use just the third fan of the mishimoto with the stock fan?? I think it would work but would have to destroy the aluminum shroud to do it. like cut it between 2 and 3 fan an leave three mounted then mount oem shroud on the other side.
Any tips on cleaning out the mishimoto rad as the previous owner installed and im sure he probally has some crud from the block in it. thanks whitrock.,
 
One more thing i forgot that is strange ; if i idol the jeep in the garage it seems ok til i close the hood then it goes to getting hot.?? thanks
 
Well the fact is most electric fan kits don't pull the amount of air as a factory mechanical/elec set-up.
 
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Any tips on cleaning out the mishimoto rad as the previous owner installed and im sure he probally has some crud from the block in it. thanks whitrock.,

You'll want to use one of the name brand cooling system cleaners. These should dissolve any crud stuck to the walls of the radiator passages.

Well the fact is most electric fan kits don't pull the amount of air as a factory mechanical/elec set-up.

No doubt that the mechanical fan moves a lot of air, but because it is so poorly coupled to the shroud (gap around it is huge), I have doubts about its actual efficiency being anything close to the amount of air that it moves. The good electric fan setups have the advantage of being tightly coupled to the radiator. However, I don't like that the shrouds with the electric fan setups probably limit natural air flow through the radiator when the vehicle is moving. But I suppose this is the wrong thread to be talking about this. :)
 
I cannot comment on your particular case but, I do remember questioning the ability of those fans when it was posted here on NAXJA. https://naxja.org/forum/showthread.php?t=1156600

Your XJ is the first XJ I have heard about that uses the Mishimoto radiator and fans. I would be following this thread to see what the failure item is.

My dual Derale fans both quit in about 6 months of each other. I modified the Derale shroud to accommodate two of the early 2000 Sebring fans. Still happy with the cooling performance. Of course I live in Florida that is flat for most parts with few days in the 100+ degree temperature.

Last summer I worked in Texas and spent many hours driving on I-35, 37 and 10 and never had an issue with high temps with the AC on. Maybe in AZ where it is very hot and hilly things may be different.
 
'You'll want to use one of the name brand cooling system cleaners. These should dissolve any crud stuck to the walls of the radiator passages.'

I've used Citric acid. MB sells it to clean their cooling systems. You can buy it at wine making places. Use the Prestone coolant cleaner to get any oil out of the system, before the citric acid. Also, do a flush after with some baking soda to neutralize the acid.
 
my 97 lost a water pump on the drive home the day i bought it

120 mile trip one way had to change it on the side of the road to get it home

it happened to be sunday afternoon and the only option i had for a replacement was an autozone special they had in stock

got it changed and got home fine but after running it on warm days with the ac on i noticed it would run hot not usually overheat but 215 n up was its norm

i tried a few different thermostats and another new water pump to no avail

after some trial and error and a lot of research i finally found a setup that

worked for my rig

here is what i used to keep mine cool

spectra radiator from advanced auto parts

motorad 195 deg thermostat also from advanced auto parts

stock zj fan clutch from a 97 or 98 i cant remember but it pulls a hell of a lot of air also got this from advance auto

flokooler high flo water pump for xj 4.0 ordered from quadratec.com

hesco high flo thermostat housing also from quadratec


i did a complete flush on my cooling system when i installed these parts

and also used an 18 psi radiator cap from advanced auto parts

i bled the system properly when i filled it with coolant and my

xj now runs 210 or under all the time even climbing steep hills or running the ac on days over 100 deg

i have even sat in a parking lot idling with the ac on waiting for a curbside pickup in 102 deg heat and no issues still at 210 the whole time

might not work for every xj but it works awesome in mine

rcfan37
 
No doubt that the mechanical fan moves a lot of air, but because it is so poorly coupled to the shroud (gap around it is huge), I have doubts about its actual efficiency being anything close to the amount of air that it moves. The good electric fan setups have the advantage of being tightly coupled to the radiator. However, I don't like that the shrouds with the electric fan setups probably limit natural air flow through the radiator when the vehicle is moving. But I suppose this is the wrong thread to be talking about this. :)


Well, if the mechanical fans were as tight to the shroud as the electrical ones, or as tight to the radiator, once your motor mounts wore some you'd be chewing up things you don't want to....

The tab on the bottom of my stock fan shroud broke off, and I found out when the fan started sucking the shroud back into the blades...sounds pretty efficient to me.......
 
Well, if the mechanical fans were as tight to the shroud as the electrical ones, or as tight to the radiator, once your motor mounts wore some you'd be chewing up things you don't want to....

The tab on the bottom of my stock fan shroud broke off, and I found out when the fan started sucking the shroud back into the blades...sounds pretty efficient to me.......

Yep, I understand the need to maintain some gap between the fan and shroud. But that doesn't change the inefficiency associated with the large gap for the mechanical fan setup.
 
good morning; a update on the mishimoto ; I talked to the mishimoto people told them there pump made our yeep overheat; they told me no not our pump; well after some debate he got it through my thick skull it was not there pump, litteraly cause they dont make pumps. it was another companys pump the po put on with the mishimoto stuff and it was a pump evidently made for fast volume rock crawling type that does something special. I put back on the factory pump and mishimoto also told me to clean things they plug easily an i did a super flushing and now the thing runs really cool even with the ac on on mild days it doesnt need the third fan at all. Lesson i learned old 6 blocks are nasty and mishimoto rads plug easily if you dont clean out the block stuff first. thanks for all the help..
 
good morning; a update on the mishimoto ; I talked to the mishimoto people told them there pump made our yeep overheat; they told me no not our pump; well after some debate he got it through my thick skull it was not there pump, litteraly cause they dont make pumps. it was another companys pump the po put on with the mishimoto stuff and it was a pump evidently made for fast volume rock crawling type that does something special. I put back on the factory pump and mishimoto also told me to clean things they plug easily an i did a super flushing and now the thing runs really cool even with the ac on on mild days it doesnt need the third fan at all. Lesson i learned old 6 blocks are nasty and mishimoto rads plug easily if you dont clean out the block stuff first. thanks for all the help..

A pic would be nice!
 
That say's it all!
 
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