I have a coolant leak on my jeep... no visible leaks. I tested for an external headgasket leak and it seemed to pass. (no pressure on a cold engine after running for 30 sec) it does has some smoke on start up but it doesn't smell sweet just very diesely. I have to add quart of coolant every two weeks or so. Jeep has 190k eco tune. Any ideas on other things to check?

I had a stant radiator cap crap the bed a couple of months after i put it on(seems to be the theme with my coolant system). I was losing some coolant at about the rate you describe and when I would open the hood there wouldnt be anything there. bone dry. I decided to see what was going on so I took the radiator fan off and put the grill blanket on and drove up a hill and steam started shooting out from under the hood. Sure enough it was blowing off at the cap so I put the stock one back on and havent lost coolant since.

_________________
2006 CRD - GTB2056 turbo by Dieselguy86, Eco Trans Tune, Lift Pump, Week's, HDS Tstat, Racor Filter, ARP's, OME 790's+Top Plate, JBA 2.5", JBA UCA, Moab's+265/75R16, ARB Bull Bar, 4.10's, TrueTracs

Could be radiator cap but also could be one one or more leaks at the host of coolant line junctions. Before concluding it's a head issue get some coolant UV dye and a UV light (under $20 from Amazon); add dye to system; drive for say 50-75 miles; use UV light to look for leaks (likely will need to do this in garage or after dark. Be sure to check odd locations including:
1. EGR cooler and associated lines;
2. oil cooler in front of turbo and associated lines
3. drip tube from heater core on firewall under coolant bottle to see if heater core is leaking, don't think so as amount of the leak would show by smell when heater is in use if it's leaking.
4. bottom edge of timing belt cover in case water pump is leaking.

You would be amazed at how much coolant can leak invisibly if the leak puts the coolant on a hot surface.

If nothing found do coolant system pressure test.

_________________
Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs

Is their coolant in the right side of the overflow bottle?

Sent from my SM-N910W8 using Tapatalk

_________________
2006 Liberty CRD Limited

Provent @ 43,000 km
SEGR in progress
SAMCO Sport hoses @ 48500 km
Goodyear Wrangler Duratrac LT225/75R16

I have put dye in today and will drive for a few days and then check with the uv light. There is only coolant in one of the tanks.

lacrosseman2010:

Do you know, (or have you performed), any cooling system modifications like an inline thermostat valve upgrade?

Turbo-diesel-freak-

I have only replaced the entire thermostat housing.

Pressure test the cooling system to 16psi.
Walk away and let it sit for 30 min.
Come back and check for pressure drop.
Look for drips and run your fingers around every coolant hose/heater hose connection, feel for wetness.
Tighten or replace clamps if necessary.
Pull all 4 glow plugs and unplug all 4 injectors.
Crank the engine and check for water shooting out the glow plug holes.

_________________
U.S. Army Retired

YES do what Flash said , so if no leaks , proceed to next step ,drain oil and pressure test cooling system , leave drain plug out for 24 hr if coolant drips out , then you have a bigger problem LINER O RINGS got cooked and leaking coolant into oil . hope it's not the case.