cooling system problem

[loggy1968]

for the last 2 months or so wj s been getting air in cooling system. I can hear it gurgling in heater core on start up in the morning, or after shutdown for more than 4 hours or so.have burped it numerous times.i also get a smell of coolant on startup for 10 to 30 seconds. can smell wether inside or outside car. cannot find any traces of leaks . didnt drive car for a few days and then expansion tank was empty. still no trace of leak . doesnt seem to be head gasket as no bubbling for coolant in expansion tank or water in oil. any ideas?

[Grippy]

Could be the pipe where the heater lines join to the core inside, ever so slight leak, that would explain smell in the cabin.

[rustynuts]

Still can be head gasket. Mysterious coolant loss need not always show in radiator cap or oil.

[bleetnblurt]

4.0 or 4.7 ? or diesel ?
did you check the leak hole at the water pump ?
are you getting a constant steam at the exhaust ?
have you checked the color of the spark plugs ?
have you checked the passenger side to see if the heater is leaking it or near fire wall?
have you listen for any "sizzle noise " while the engine stoped after heated?
have you checked the overflow bottle for any cracks ?
and checked the radiator cap is working ?
have you checked to see if any condensation at the oil fill cap ?
have you checked the top rad hose to see if abnormal pressure ? (or loss of)
have you heated it up to check to see if the overflow bottle is filling up ?
and the list goes on and on and on for checking .
buy a chem test , if you cant find the problem , could be as simple as a rad cap , or bad as a cracked head for not using (or changing) coolant fluid. GOOD coolant fluid.

[loggy1968]

Originally Posted by bleetnblurt

4.0 or 4.7 ? or diesel ? 4.7
did you check the leak hole at the water pump ? yep good
are you getting a constant steam at the exhaust ? nope
have you checked the color of the spark plugs ? pia job - will have to
have you checked the passenger side to see if the heater is leaking it or near fire wall? nothing on engine side - will have to check inside
have you listen for any "sizzle noise " while the engine stoped after heated? no sizzle
have you checked the overflow bottle for any cracks ? bottle is good
and checked the radiator cap is working ? cap works
have you checked to see if any condensation at the oil fill cap ? all good
have you checked the top rad hose to see if abnormal pressure ? (or loss of) all good while running
have you heated it up to check to see if the overflow bottle is filling up ?
and the list goes on and on and on for checking .
buy a chem test , if you cant find the problem , could be as simple as a rad cap , or bad as a cracked head for not using (or changing) coolant fluid. GOOD coolant fluid.

do 4.7's have a history of head cracking?

[bleetnblurt]

they can wear out from not using a good coolant , and any alloy head can crack , but most cases is gasket,
try going through simple things first , run the jeep to look under bonnet as it heats and is heated feel the top hose , (see if pressured ) look at the back to see if any steam , (not when first start but after temp is up)
look at the over flow to see if filling , if it does to quick , check rad cap ,
due to there is a foam under the carpet , it can be hard to see if it is leaking from the heater core , take off the kick panel and side trim to look , see if and dis color there .
if pressure is building in it look at the top rad hose to see if out of shape , and feel the bottom hose to see if hot , most times if combustion gasses are leaking into the system it will happen while driving , go for a drive , pull over look at the filler bottle (overflow) is filling up too high , check your rad cap , as well , (after it cools) the worse thing is using cheap nasty coolant , and coolant does not last forever . if you have trouble take to a place to have them check to see if any NOX/COX so on is in the coolant , or go to a bursons , repco and buy a kit and test yourself.

[fester]

Did you check under the carpet. The heater core can leak under the carpet and with the insulation under the carpet the moisture doesn't necessarily surface on the top of the carpet.