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Over heating!

pair8hd

NAXJA Forum User
Location
Derby, Kansas
I did do a search.

I have an '88 (w/ stock rad.)& '90 (w/ GDI 3 row) XJ. They both started overheating during this 100 degree+ weather we have been having. It seemed the closed systems on both of them were leaking and had air in the system. So I converted them to open systems like described here, Easiest and Cheapest Open Cooling System .
I am still overheating on both XJs and have coolant spaying out of the overflow bottle. The '90 XJ has a water pump and fan clutch that is about a year old and I have never changed the '88's water pump. Driving on the highway keeps the temp down on both of them but it's the stop and go that makes them overheat.

Any suggestions?
 
try replacing your fan clutch if you run fine at speed then stop and go you heat up its usally an indicator for the fan clutch not locking up....
luck
themud
 
Make are the electric fans coming on long before it boils.

Also, are you sure it is boiling. I've seen two this week that had blown head gaskets and would build up enough preasure to blow it out the overflow. Even sounded like boiling water.

Slow speed = air flow. Check the drop accross the radiator. If I remember correctly I was getting a 30 degree drop during my overheating day's and it still wasn't enough.

Make sure the rad and A/C condensor aren't plugged with bugs. Mine would alway's fill between the two.

Good Luck,
Lincoln
 
Two questions:

(1) In doing this "conversion," did you remove or bypass the stock plastic bottle on the firewall?

(2) I've never seen a catch bottle quite like that one. Do you fill it halfway when it's cold? How/where do you add coolant if your system is slightly down on coolant?
 
pair8hd said:
have coolant spaying out of the overflow bottle

What is your cap rated at? Should be a minimum of 16 lbs to hold the proper pressure.
 
Re: Re: Over heating!

MaXJohnson said:
What is your cap rated at? Should be a minimum of 16 lbs to hold the proper pressure.

True. But the article he followed (typical JU advice) said nothing about removing or bypassing the stock plastic bottle on the firewall. If that's still in the circuit, its pressure cap may be leaking and not allowing the system to hold pressure.

An overflow/recovery bottle is intended to be filled 1/3 to 1/2 full when the system is cold. I see no way to fill or to check the level on the bottle shown in that write-up. I do not understand how it can possibly be used as an overflow/recovery bottle.

Which is why I initially responded with questions rather than answers. I think we need to know more about how the system was modified before we can offer any useful help.

I just have to say that, on the basis of the link provided, that's about the most half fast cooling system mod I ever saw.
 
Re: Re: Re: Over heating!

Eagle said:
True. But the article he followed (typical JU advice) said nothing about removing or bypassing the stock plastic bottle on the firewall. If that's still in the circuit, its pressure cap may be leaking and not allowing the system to hold pressure.

An overflow/recovery bottle is intended to be filled 1/3 to 1/2 full when the system is cold. I see no way to fill or to check the level on the bottle shown in that write-up. I do not understand how it can possibly be used as an overflow/recovery bottle.

Which is why I initially responded with questions rather than answers. I think we need to know more about how the system was modified before we can offer any useful help.

I just have to say that, on the basis of the link provided, that's about the most half fast cooling system mod I ever saw.

The pressure bottle is gone. The new heater valve is used to take it out of the loop. I know the article didn't address this but I knew what the valve was for.

The JAZ overflow/recovery bottle is junk, but still serves it's purpose. For the price I paid for it I should have just gone with a conventional clear bottle from the bone yard.

Speaking of JU (your people miss you Eagle ;) ), here's a better write-up that addresses taking out the pressure bottle,http://www.jeepsunlimited.com/modules.php?name=News&file=article&sid=42 .
 
A couple of minor things to checkout:

1) After my trip to Moab last year I had the same sort of overheating as you, fine on road - overheat in stop and go. I replace the fan clutch. It didn't make a difference.
I mount my Hi Lift on the front bumper. I oiled the jack while mounted on the bumper before we left for Moab. The wind blew the oil all over the left side of the radiator. While in Moab this attracted a whole bunch of that red Utah dust clogging the radiator. The AC coil appeared fairly clean but I could see the red dust caked solid on front of the radiator. Washed it out and problem solved.

2) My Grand Cherokee does not like a rich mix of antifreeze/water. It will run very hot if I have something like a 70% mix of antifreeze. It's happy at 50%. Antifreeze itself doesn't transfer heat as well as water.
 
Re: Re: Re: Re: Over heating!

pair8hd said:
The JAZ overflow/recovery bottle is junk, but still serves it's purpose. For the price I paid for it I should have just gone with a conventional clear bottle from the bone yard.

Okay, no OEM pressure bottle.

The JAZ bottle has no way to check level visually, and I see no fill cap. When cold, do you fill it partially, all the way, or not at all?

The coolant expands when it gets hot. That's why the stock bottle was to be filled only halfway, and why on the open systems the overflow/recovery bottle is only supposed to be filled halfway. As the system gets hot, the "excess" coolant generarted by the expansion goes into the overflow bottle. When the system cools down, that small rubber/copper disk in the center of the radiator cap acts as a one-way check valve to allow the "excess" coolant to be sucked back into the radiator. If the JAZ bottle isn't large enough to handle the volume of expansion, there really will be "excess" and that will be dumped. Then when the system cools down the system will suck in air.

Methinks you probably need a larger expansion bottle with a real fill cap.
 
Re: Re: Over heating!

MaXJohnson said:
What is your cap rated at? Should be a minimum of 16 lbs to hold the proper pressure.
WTF?
I just bought a factory radiator cap from the dealership, and it says it calls for a 14 lb cap.
It's what it says on the cap. I haven't put it on yet, maybe I should take it back and question them again about the difference in the pressure ratings. I'm confused!
Dan.
 
I am having a heating problem also but mine gets hot when I am on the highway. When I get over 65 mph my temp gauge goes up to about 220 and if I go over 75 it gets close to 240. It hasn't overheated yet but I am concerned about it gets too hot for to long. Over two years ago I had a new radiator installed and last year had it rodded out because I had the same problem last year when it got up into the 90's. If it is 85 or lower my temp is fine but if any higher then that it starts getting over 210. It runs fine in town and just sitting.
 
old dutch said:
Replace the water pump.
Perhaps Try:
A 150 thermostat.
Aux Oil Cooler.
Vent in hood.

DO NOT TRY a 150-degree thermostat. It's way too cold. The system is designed to run with a 195-degree thermostat. The computer switches from open loop (warm-up mode, pre-set fuel map) to closed loop (responds to O2 sensor and other data inputs) at somewhere around 160 to 165 degrees. Therefore, a 180 is the lowest thermostat you should consider using, and there's really no reason to run anything other than what the factory calls for. With a 150 in there you'll always be running in warm-up mode.
 
Ladeback XJ said:
I am having a heating problem also but mine gets hot when I am on the highway. When I get over 65 mph my temp gauge goes up to about 220 and if I go over 75 it gets close to 240. It hasn't overheated yet but I am concerned about it gets too hot for to long. Over two years ago I had a new radiator installed and last year had it rodded out because I had the same problem last year when it got up into the 90's. If it is 85 or lower my temp is fine but if any higher then that it starts getting over 210. It runs fine in town and just sitting.
If you figure this one out, let me know. I'm having the same issue. Just about everything in the cooling system has been replaced. Next is a new lower radiator hose.....Eagle has previously mentioned that if the internal spring in the lower hose collapses it can cause an overheating condition while driving at highway speeds.

Tom
 
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