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suggestions for overcooling?

O

outlander

NAXJA Forum User
Location
Columbus,Ohio
Overhauled the cooling system on my 89 4.0 5speed a few months back and now that its cold here I'm overcooling.

What I did:
new open system including a cse 3 row radiator,MR gasket 195* balanced stat,dual electric fans wired to a manual switch,50/50 coolant mix. and a autometer temp gauge with sender screwed into stat housing.

Drove it around today with the temps in the lower 40's and according to my autometer gauge the temps never got above 180* and the stock gauge read just under the first line also.

If the autometer gauge is reading 180* that would mean the actual engine temp is probably around 170-175* (verified by my IR thermometer)

So what is the fix here?I'm sure my mileage is down because I'm running in open loop alll the time......
 
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well with all those mods wouldnt you expect the temp to go down? a normal jeep runs around 200-210 with those mods you have seems like it should be running around there.. JMO
 
Well, kill the electric fans.

Or, have the "main" or most powerful fan come ON when the temperature of the coolant is 200 degrees, and have the secondary fan come ON when the coolant reaches 217 degrees, that would replicate the original OEM setup.

Override switches would be nice if you feel there are times when you want to kill both fans--water crossings--and times when you want both to be on--rock crawling on hot days, heavy loads and steep climbs.

Also, take a lesson from the Big Rigs--put some cardboard in front of the radiator to block air flow so the engine will run hotter.

And, the Stant Premium is the best thermostat, period. :twak:
 
running a stant premium on mine w/the same problem. Im wondering if deleting the fan shroud for the efan(s) could cause that many gremlins. Ill try the card board thing one of these days and get back to everyone.
 
The thermostat regulates the temperature. All those suggestions are great I guess, but the cooling circuit doesn't open until the coolant in the block reaches a certain temperature, so you can put whatever you want in front of the radiator but why? The radiator and/or fans don't come into play until the thermostat opens.

First thermostat I bought for my XJ was an AutoZone special that stuck open from it's first use. I knew this because I never would reach operating temperature, and it'd take forever to get to ~180 or so. I went to the dealer and spent $8 on a Mopar thermostat, pulled the old one (sure enough it was stuck wide open), installed it, and I've run at ~210 since. It also reaches operating temperature very quickly. It's something to check out...
 
RENIX will be in closed loop at 180.

I have a similar set-up as you do, 3-row all metal rad, dual electrics, high flow water pump, new OEM bottle, and most importantly a freshly rebuilt and bored out 4.0.

I was concerned that the "closed" system could not keep up with the bored out engine but the opposite happened, it works too well. I have my primary fan switched on by a sensor that I put into a later model T-stat housing (the later models have a sensor bung there) and I blocked off the grill with cardboard. I also installed the rubber lower engine cover to keep air from coming in from underneath. It works good.

I live in a mild climate here in VA, the coldest it gets in the winter is in the mid-teens to lower 20's
 
Two things to rethink: First the gauge measures coolant temperature not engine temperature. Second the thermostat isn't an off-on binary switch, it's a mechanical device that opens incrementally as temperature increases--with a 195 tstat you would expect it to start opening at about 180 and be fully open at about 210 (that is 15 degrees either side of 195).

Sounds like your cooling system is just working too well. You might want to put a higher tstat in there but I'm guessing you'll see coolant temperatures fluctuate and still drop. I like the suggestion of partially blocking the radiator. It's winter you can do it.
 
robert2008 said:
The thermostat regulates the temperature. All those suggestions are great I guess, but the cooling circuit doesn't open until the coolant in the block reaches a certain temperature, so you can put whatever you want in front of the radiator but why? The radiator and/or fans don't come into play until the thermostat opens.

First thermostat I bought for my XJ was an AutoZone special that stuck open from it's first use. I knew this because I never would reach operating temperature, and it'd take forever to get to ~180 or so. I went to the dealer and spent $8 on a Mopar thermostat, pulled the old one (sure enough it was stuck wide open), installed it, and I've run at ~210 since. It also reaches operating temperature very quickly. It's something to check out...
Click to expand...

x2. come one guys it ain't that hard. Running hot can be caused by a lot of things, but there isn't much that can cause it to run cold (unless it's -40 or something).
 
my temps went up a decent amount when I got lazy and ziptied my license plate to the middle of my grille to pass inspection... can't suggest it for looks, but it does pretty good on the functionality scale! I'm still running a little cool as it's winter.
 
never had a vehicle that was so touchy on the cooling side. just rebuilt my 1999 4.0 and i notice its running at about 195-200. i guess thats ok but i wish i could get it full of coolant! ive parked it uphill, downhill and d--- near on its roof and best i can do is just short of 10 quarts.
 
Find out why your thermostat is stuck open or not performing properly. At 180, the thermostat shouldn't be open all the way allowing the coolant to circulate.

Ever tested one? You've got an IR gun, put it on the skillet on the stove and watch it open and take some temps.

With a good thermostat performing properly, there's no reason why you shouldn't run effectively in the winter. It's not like you doubled the radiator surface, it's still an XJ.
 
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This may not be as related as I don't have a renix(97 here). I did have the same thermostat however and was over cooling in the winter. I swapped it out today actually with a stock(dealer) thermostat and my temp is perfect now in the cold.

I have a csf 3core, high flow water pump and high flow tstat housing, stock fans. In the summer my temp was perfect but as soon as it got cold... I'm thinking the thermostat just flows too much when it is barely open.
 
iwannadie said:
This may not be as related as I don't have a renix(97 here). I did have the same thermostat however and was over cooling in the winter. I swapped it out today actually with a stock(dealer) thermostat and my temp is perfect now in the cold.

I have a csf 3core, high flow water pump and high flow tstat housing, stock fans. In the summer my temp was perfect but as soon as it got cold... I'm thinking the thermostat just flows too much when it is barely open.
Click to expand...



This is what I was thinking.I'm going to get an oem stat and see what happens....Does it warm up faster now???
I tested this one before I put it in and it was functioning properly.....it opens wide!!
Dual fans only come on when I flick the switch...so its not the fans......
Renix is in closed loop at 180*???

I'll report back this weekend when I get the mopar stat in.
 
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outlander said:
This is what I was thinking.I'm going to get an oem stat and see what happens....Does it warm up faster now???
I tested this one before I put it in and it was functioning properly.....it opens wide!!
Dual fans only come on when I flick the switch...so its not the fans......
Renix is in closed loop at 180*???

I'll report back this weekend when I get the mopar stat in.
Click to expand...

I drove this morning and it was 45ish degrees and I was up to 210 and stable temp by the time I left my neighborhood. I don't sit and idle to warm up either, as soon as I have oil pressure I drive away. So, yes it warms up perfect and never went over 210.

With the previous thermostat I could drive 45 minutes in 40-50 degrees stop and go traffic and never reach 180-190 degrees.
 
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