I have been loosing alot of water these last few weeks. Changed the oil a few weeks ago and did not see any water mixing. Before leaving for work tonight I filled the reserve bottle. When I arrived at work it was empty and the oil is brown. Mind you it was a 60 mile drive at 80 miles an hour. Did not check the oil prior to leaving. I have no steam coming from the exhaust. The engine sounds as good as the day I bought it brand new.

The water always seems to be rusty colored.

I have just over 80,000 Miles.

I had one event of over heating in February of this year when, but shut the engine down immediately. The vehicle was towed home. Replaced the thermostat, water pump, radiator and radiator cap.

Warped head or just a gasket. What do you think?

I'd bet 2 to 1 that you have a simple water leak.. A small drip now and again that you have not bothered to find!!!
A cracked head ir a leaky head gasket will ALWAYS show itself by purging the coolant system from COMPRESSION entering into the coolant system...
YOU HAVE A SIMPLE COOLANT LEAK!! Look closely and FIND IT!
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

Should the oil look like chocolate milk? I think I forgot that detail.

Is the oil over the full mark? Coolant in the oil raises the level. It is near impossible to get coolant in the oil without also filling the coolant system with compression..
It is sometimes possible when the engine is NOT running.
Your description is a valid one for a small leak at the radiator or a hose or even the coolant pump itself..
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

1 to 1.5 inches over. Milky brown color and smells different. When i pull the radiator cap off the coolant comes out in spurts.

I will look for a leak today. I haven't really looked closely for one yet. Automatically thought of the head gasket from a past chevy 2.0 4 cyl. expirence.

Sounds like a blown HG with the milkshake. Suprised on such a low milage 4.0L. Engine compression test and/or cooling system pressure test should show where the leak is.

The rusty water in the rad makes me wonder if your radiator is bad. My 91 XJ had the rusty brown water problem for a long time and finally resulted in a bad overheat one day. Replaced the rad,water pump and thermostat and things have been fine with it for a few years now. The anti collapse spring inside the lower rad hose rusts out pretty easily, mine was rusted into pieces and probobly contributed to plugging the radiator.

Took about an hour to chemically flush all the brown nasty water out of the block and cooling system.
Runs alot cooler too,below 200 instead of over 210.
Good luck, hope it's just a rad or gasket and not anything major.

If it is OVER where you had it filled... SOMETHING got in there.. Down here where it does NOT get cold enough to freeze the coolant I run PURE antifreez.. The lack of water in it keeps all rust out of the system.
I'd fill it up and run her till the pressure rises in the coolant then I'd shut her off and look for the exterior leak.. Then I'd make sure I knew what I was looking at in the oil.. Before I took it apart.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

Thanks everyone for the info. Drove the jeep home filled the radiator back up and waited for the pressure to build. Found no leaks. Is it at all possible that I am lossing the water just under the strain of driving the highway but not under round town?

Compression check can be done on that engine in less than 20mins. Thats how I found the head gasket leak on my 91 4.0. I was losing coolant; not as much as you though. Rear cylinder was 30 lbs lower than the other 5. It ran perfectly too, no smoke.
You could also run it by a shop and just have them hold an exhaust gas tester over the reserve bottle or radiator with their caps off while engine is running. This could show compression blowing into the cooling system if the reading is high.
With the engine hot, pull the plugs 1 by 1. Put a 1 foot length of rubber hose (2 feet if your not very flexible yourself) tight against the spark plug hole and smell for antifreeze odor. If so it will indicate a head gasket. If you do the head gasket, have the head resurfaced just to make sure. Good luck.

I have found slow leaks to be just that...SLOW! I'll still bet 2 to 1 the coolant is leaking and you simply have not found it yet..
Wait till noght and then get a light and look everywhere for the small green dot that will be a single drip of coolant.. Spend lots of time looking..
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />