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disapperaring antifreeze

785 views 9 replies 7 participants last post by  Dextreme 
#1 ·
I bought a 2001 TJ for my son not long ago and noticed it is losing antifreeze but not leaking that I can find. It is behaving like a cracked head or maybe head gasket but I'm not seeing any evidence of foreign stuff in engine oil. Is there anything that could cause this other than cracked head. I just checked it more closely and it appears to lose about a half gallon every 150 miles or so. Plenty of water in exhaust and after driving it about 10 miles on highway oil pressure does drop, all signs of cracked head. I'm no mechanic so just going on what I have read here and elsewhere, but was expecting evidence in motor oil if this is the case. Any ideas?
 
#3 ·
I think this is the issue especially since you said "plenty of water in the exhaust". The would indicate to me that the fluid is going directly into a cylinder and blowing out the exhaust. Pull the spark plugs and read them and you should be able to tell. This could be a blown head gasket and not a cracked head.
 
#4 ·
After your Jeep warms up do you see water/moisture coming from the tail pipe? It's not unusual for moisture to come out when cold/warming up.

Look carefully in all the usual places for coolant leak, right passenger floor(leaking heater core) around the water pump & pump pulley, around the thermostat housing, more difficult to see is the 5 freeze plugs under the exhaust manifold, check you hoses and clamps too.

Most auto parts dealers will lend you tools, borrow a radiator pressure tested, pump it up and see if you can locate a leak.
 
#6 ·
Either one could cause diminished oil pressure. I am going by your statement "plenty of water in the exhaust". I wouldn't consider that "normal condensation", but I am also not seeing what you are. Other signs could be as follows:

1. Combustion chamber producing steam from the exhaust and at least one wet spark plug.
2. Oil in the coolant.
3. Continuous bubbles from the radiator (with cap off) while the engine's idling.
4. Low compression in one cylinder or two adjacent cylinders.
 
#10 ·
When my TJ was loosing coolant (no drips on garage floor), what I did first is fully degreased the engine so it would be easier to determine what was old fluids and what was new fluids. After degreasing and driving for a day or two, I took a very bright flash light and scanned the motor....I could now see coolant running along the oil pan, traced it back up to see that it was seeping out the gasket of the waterpump. So I then knew it was time to replace the pump and thermostat.

In your case, if it does end up being a "bad headgasket"...chances are the TJ was overheated at some point. It is not uncommon for a previous owner to fix the cooling system issue that caused the overheat, but never fixed the bad head gasket as a result of the overheat.
 
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