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Brand new cooling system runs at 240 Degrees! WTF?!?!?

R

ResurreXJion

NAXJA Forum User
Location
N.E.PA
New MOPAR 195 T-stat
New Water pump
New GDI 3 core rad
New severe duty clutch fan
New temp sending unit
New belt, new hoses, new rad cap, new heater control valve, new, new, new.....

The cooling system is running between 220 and 240 with the guage alternating up and down between these temps, wether idling or driving its fluctuating 20 degrees in either direction. Will NOT hold a steady, even temp, and worse yet, the coolong system will pressurize once the t-stat opens.....and the pressure never releases until it cools down.

I am ata total loss. I bought the best of the best in parts, and dropped about 500 bucks into it......and it still overheats, temp jumps around, and pressurizes.

ANY IDEAS What could be wrong PLEASE!!! I need this car for work.

Thanks.
 
new radiator cap? Silly question, but it is not listed. It would probably be good to know what year you have as well.

You could also try running it with the cap off, yes I know burping the system is really only for closed systems, but it will still help out an open system to pull all the air pockets out.

Are you sure that the sender and gauge are working correctly?
 
Year?

Open or closed system?

Does the thermostat have the breather hole(s) in it?

Sounds like trapped air making the T-stat cycle.
 
wolfpackjeeper said:
You could also try running it with the cap off, yes I know burping the system is really only for closed systems, but it will still help out an open system to pull all the air pockets out.
Click to expand...

Burping is not just for closed systems. On any system you need to get the air out of it for it to work properly.

But this is my guess as well. Unless, depending upon year there was/is a reverse rotation pump that is available(as stock) on a couple of the earlier years. Did you look/compare the two pumps when you changed them or did you just take the old off and toss the new on? The only physical difference is that the impeller is opposite(directionally wise) to each other. I work at a parts store and had this happen to a customer I was helping. And it was on a Jeep, I just cannot remember the year.


Ecomike said:
Year?

Open or closed system?

Does the thermostat have the breather hole(s) in it?

Sounds like trapped air making the T-stat cycle.
Click to expand...

X2 (not attacking op but.....) why does every one think we know what they drive:dunno::dunno:

But yes please post year and is it a closed system, open system, converted system(was closed now open). What motor it has will help to, is this a street rig(DD), multi rig(DD and wheeler), or just a trail rig?
 
Possibly guage sensor or connection?
Have you verified that the temp is ACTUALLY doing that?
Guages can be filthy liars some times-just like politicians.

Nick
 
Im the OP and to answer a few questions..........

- It is a 1996
- It has the 4.0
- Open cooling system
- 5 Speed, so no internal tranny cooler.
- Dual duty rig; Daily driver and light off road weekly.
- Yes, new 16 lb rad cap, and everything has been replaced except heater core.

.............And its still around 220-240. I DID purge the air from the sytem by yanking the temp sending unit from the back of the head while parked slightly downhill, then parked it slightly uphill and ran it for twenty minutes with the radiator cap off to get any air leftover out. (yes got very hot while idling.)

I CHECKED for head gasket issues by checking for bubbles in the raditaor, none. Does NOT smell like exhaust. I put a condom over the radiator neck and ran it up to about 2200 RPM, and no air got trapped......so most likely no head gasket issues.

So.....I ran it hard all day regardless of 240 + degree temps, wildly fluctuating temps and big, swollen radiator hoses..........

I AM CLUELESS TO WHAT IS WRONG WITH MY COOLING SYSTEM!..........Worse, thiws is the THIRD time in five years that I have COMPLETELY rebuilt it with quality, hi performance parts, but it has always ran cooler when finished. Not this time SIDENOTE: It was fine before I I upgraded this time around, but hoses and belts needed to be replaced and the radiator got pinched on the trail. So I replaced EVERYTHING as a good measure, and now THIS:

Any ideas are appreciated.
 
I can think of fisix possibilities.

Wrong water pump (look for a cast letter R on the housing, can't
remember which is which right now)
Wrong belt routing (check FSM or look at a buddies rig)
Bad or backwards thermostat (completely remove for diagnosing)
Bad fan clutch (search)
Collapsing lower hose. (watch it)
Running way to lean (pull the plugs and do a plug reading)
 
is your e-fan turning on when it gets this hot?
 
old_man said:
I can think of six possibilities.

Wrong water pump (look for a cast letter R on the housing, can't
remember which is which right now)
Wrong belt routing (check FSM or look at a buddies rig)
Bad or backwards thermostat (completely remove for diagnosing)
Bad fan clutch (search)
Collapsing lower hose. (watch it)
Running way to lean (pull the plugs and do a plug reading)
Click to expand...
 
old_man said:
I can think of fisix possibilities.

Wrong water pump (look for a cast letter R on the housing, can't
remember which is which right now)
Wrong belt routing (check FSM or look at a buddies rig)
Bad or backwards thermostat (completely remove for diagnosing)
Bad fan clutch (search)
Collapsing lower hose. (watch it)
Running way to lean (pull the plugs and do a plug reading)
Click to expand...


X2 on most of those. especially the the possibilty of the wrong water pump, a reverse flow based on his last post. Has happened before to others where they were handed the wrong pump. I have heard it is possible to install the belt wrong, but I doubt he did, sounds like he has done this work before. Same for installing the thrmo backwards, unless he got distracted. I don't buy the lower hose issue, not on a new install, open system 96 at 240 F.

Since it was fine before all the cooling parts were changed, any possibility the water pump is bad (loose impeller), or that the radiator is bad (right out of the box?).

Too lean is possible, but only if started coincidently right after he replaced parts, since it was not running hot before the parts were replaced.

A bad NEW fan clutch is real possibilty!!!!!!!!!

One more idea! Try the old temperature sensor that feeds the dash gauge! The new sensor may be lying!!!!!!

The fact that the hoses are bulging, says it may not be the new Temp sensor, but it should be verified before you chase your tail any further.

Lastly, the new thermostat may not be opening all the way.
 
Since you have a 96, I would use a scan gauge and compare the cts temp with your dash gauge(oops forgot to sign in--Gradon).
 
The heater hoses bypass the thermostat and help keep the coolant near the thermostat near true engine temperature (instead of hot and cold spurts or bubbles of coolant). If the bypass gets blocked off at the heater valve, the heater core or by the thermostat gasket the temp gage will take wild swings as the thermostat opens and closes. Try turning the heater on and see what happens.
Installing the thermostat in basackwords is something I believe most every mechanic has done at one time or another. Haste makes waste.
Trapped air. Try squeezing the top radiator hose half a dozen times, with the motor running with it up to operating temperature. This often gets trapped air moving.
X2 on the reverse rotation pump, I got lucky and brought my old pump to the parts place with me and lucky again when I decided to look at the new pump before taking it home. Set them side by side on the counter and happily noticed the fins on the impeller were facing opposite directions on the two pumps.
Double check the cap.
Fan clutches also come in lefts and rights.
 
$.02-

-Misrouted hose / heater valve -(compare to another 96 xj)

-X3 Thermostat -(as above posts)

-Radiator cap not fitting properly or bad.

-No teflon sealer on temp sensor (Grounds thru threads)

-Temp sender -White connector.
--------

-Test temps with IR

-Test thermostat by boiling in pan of water. (If its really gone past 240* probably is bad)

------------------
Remotes-
-Bad hose (blocking flow)
-Radiator (even new ones are sometimes bad)
-clogged heater valve or not fully moving thru range.
-the small tube connection on radiator neck cracked and leaking air or leaking hose.

Good Luck
Orange
 
Again, all new parts, all new from MOPAR.

Heater control valve is correctly installed, and the thermostat will only fit in one direction: The right way.

Removing T-stat and installing a 180 degree T-stat results in the proper 210 bguage reading.....BUT it takes forever to get to operating temp and quickly dips below 210 when driving. Not good, considering the ECU needs to be @ 210 to close the loop and operate properly.
.....So the correct MOPAR 195 t-stat went back in. And all of the problems are back.

I am a mechanic. Not myself nor anyone else can figure this out, nor have we ever seen it before.

Keep your Ideas coming I will try an IR reading tomorrow.

Thanks for the replies.
 
so swapping the thermostat stopped the erratic and high temps? and you put the new one back in? i think your "new" thermostat is bad.
 
ResurreXJion said:
Removing T-stat and installing a 180 degree T-stat results in the proper 210 bguage reading.....BUT it takes forever to get to operating temp and quickly dips below 210 when driving. Not good, considering the ECU needs to be @ 210 to close the loop and operate properly.
.....So the correct MOPAR 195 t-stat went back in. And all of the problems are back.

I am a mechanic.

Thanks for the replies.
Click to expand...

HELLO Mc FLY

So, when you change the stat, it stays cooler? OK, now you put the NEW t-stat back in it runs way to hot..

What does this tell me? BAD stat..You havent ever had a BAD NEW stat? I only have a few, okay 30 years working on cars, but i have had a couple of BAD NEW stats..
HTH

We can only pray
 
1990JEEPXJ said:
so swapping the thermostat stopped the erratic and high temps? and you put the new one back in? i think your "new" thermostat is bad.
Click to expand...
That seems pretty obvious to all of us but the OP. Just because a T-Stat is new, does not mean it is working properly. It could be miss labeled, defective out of the box. Try another brand if you want 195 F.
 
I also think its worth a couple extra bucks to buy a "fail-safe" stat(way cheaper than a warped/cracked head or block).
 
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