My 2000 Jeep Cherokee (I've heard of the defective 0331 head which is why I'm more worried) has always ran a little hotter than normal under typical driving conditions (just barely over 100 degress celcius maybe about 101-102 which I believe is 210 fahrenheit on the American gauge cluster) and maybe around 105 degrees (1 line past 210 fahrenheit) when going up steep hills/offroad/in traffic when it is 20+ degrees outside. I've been looking for symptoms of a bad gasket/cracked head and the coolant under the radiator cap is greenish brown but I'm thinking it's just because its dirty as it has never been replaced by me. My coolant in the reservoir seems to go down slowly and I eventually end up adding more until it reaches the full line. The last time I filled it was in mid January and today it was just below the add line. When the engine is under load and the air vents are completely off my windshield begins to fog up in the middle, I'm not sure if this is related or if its something with the heater core as it smells very strongly of coolant when the heat is on but I haven't noticed the passenger floor being wet. I've posted a video on youtube of my exhaust here as I think there is a bit too much water coming out of the exhaust here:
So far I've looked under the oil fill cap for the "TUPY" casting but couldn't see anything and the oil inside didn't seem to be contaminated with coolant, and the same with the oil in the oil pan on the dipstick didn't appear milky. The coolant in the reservoir does look a little more brown than the coolant in the radiator cap. I looked in the reservoir and noticed a couple bubbles when I squeezed the upper rad hose but didn't see anything actively bubbling up with the engine running. I'm wondering if there is anything else I can check before getting a compression test done as I am away from home and don't really want to pay a shop as I don't have a lot of money at the moment. I'd like to know whether it is the gasket or a cracked head so I'd know if I could fix it myself or if the whole head needs to be replaced.

 

There is a test kit for exhaust gasses in the coolant. Highly recommended.

That will confirm if you have a head gasket/block problem.

However, the only way to be sure which problem you have is to pull the head.

 

From the sounds of it, you may just have a slight heater core leak that's not so bad as to be forming puddles on your pass side floor, but enough to lose a little coolant and fog the window. I may be overly optimistic though.

Do the testing as Mark suggested. You might be able to rent a compression test gauge - though it seems it's a lot harder to find "loan-a-tool"'s in Canada than it is in the states from what other Canadian members have reported.

Good luck and let us know what you find.

 

I was hoping it's the heater core (even though it's a pain the *** to replace). Interestingly I just found out yesterday that Canadian Tire loans out tools and they had a test kit for exhaust gasses in the coolant. My question is does that check for any type of leak in the head gasket or do I also need to do a compression test? I've also never done a compression test and watched a video showing that you have to take out the spark plugs but my Jeep has a coil pack so I was wondering what the difference would be if I had to do a compression test as well. I'm just waiting for the rain to die down a bit then I'm going to test the coolant, will update once done!

 

There are varied problems that one can have with a bad head gasket/cracked head. Depending on the type of failure, it could be any or all of mixed Exhaust gases, oil and coolant.

Oil and coolant mixing is something that's fairly obvious by visually inspecting the fluids.
Exhaust gases are less obvious, so that's where a good test kit comes in handy.

Compression testing will tell you how well the cylinder holds the pressure when the piston compresses the air/fuel mixture (or during testing, just air). If a head gasket has failed at a particular cylinder, the cylinder will test significantly lower than the others.

I would do both to be sure that your engine is sound.

The spark plugs are under the coil pack. There's no difference - you need to disable spark and fuel before testing anyway so just pull the coil pack off and take the plugs out normally.

 

Also, if your cooling system isn't holding pressure (as would be the case with a hole in the heater core) the operating temp will rise a few degrees.

 

The only way I know of to verify if it's cracked block, cracked head, or just the head gasket, is to pull the head off and look.

The problem is they all cause the same symptoms. With the exception of the infamous 0331 crack, of course, which can often be seen through the oil cap.