99 XJ w/ 4.0L 120K; Had a major service a while back checking EVERYTHING, flushed radiator, new hoses, compression test, major tune, etc. Now I am adding coolant every couple weeks. At least a quart.
No oil in the coolant, no coolant in the oil, no leaks under the engine.

Where's the coolant going?

Also recently replaced the radiator cap with the stock unit direct from the Jeep dealer.

And the truck runs great!

Any help on where to look?

Thanks

 

i got a small leak myself i suspect maybe the thermostat housing or waterpump, Check where the bottom crank is and the oil pan and see if theres a little bit of coolant there. Do you notice a drip anywhere?

 

Fire it up and look at
radiator
connections
radiator
underneath rad cap
water pump weep hole, underneath water pump, tube for heater core hose, rad hose connection
heater core connections at firewall, water pump tube, and t stat housing
t stat housing heater core connection, underneath t stat, t stat hose connection
look on crank pulley

Sometimes it might only leak at higher pressure, rev it up a little bit and watch

 

Is there an odor of coolant in cabin? If so, the leak could be in the heater core.

If the freeze plug on rear of engine block is leaking, coolant will pool inside bell housing which hides the leak when parked.
If there is an issue with cylinder head, coolant could be entering exhaust. The ethylene-glycol will eventually foul oxygen sensors and give a CEL code. (this is the issue with my jeep, however it runs great)

 

I drove mine for a year and a half with a cracked head and very little weekly coolant loss and it ran great. I never did get a CEL code for the O2 sensors but I'm sure it was coming at any time. I did not know it could foul the sensors, thank you.

 

Thanks,
I check these things. No smells in the cabin but definitely that hot engine smell up front after a drive. Looks like the thing could hide head trouble for a long time, If I got current leak-down test, wouldn't that give me a yes or no regarding serious head issues?

 

If that smell is somewhat sweet it's coolant.

 

A block tester will check for exhaust gasses in coolant. Available at most auto parts stores. http://www.blocktester.com/instructions.htm