K-man

Just got a 2003 Jeep Grand Cherokee. Was driving last night started to overheat. I opened the hood noticed antifreeze. My lower hose to the heating core blew off. After replacing it and filling with coolant i took it for a drive. Then it would not blow heat on the inside and the temp gauge was staying at cold. Then it started to over heat. Im thinking it blew off cause of some pressure back up. Is it the core itself thermostat or water pump PLEASE HELP

Flowpro

I would bet it started with a loose hose clamp that let the hose come off the heater core. Then you added antifreeze and got an air pocket in the core. (had the same thing when I changed my antifreeze a few days ago in my XJ) On a cold engine try loosening the hose clamp on the core, start it up and wait until antifreeze drips out. On mine I installed a back flush kit in the heater hose so I just unscrew the cap until fluid comes out.

A new thermostat wouldn't hurt either.....only two bolts and a few minutes to change.

K-man

Yes the bottom heater core blew off pretty much lost most of antifreeze. So i put the hose back on filled it up. I started the jeep the temp gauge was under half way i let it idle the temp didn't move. So i drove it around the block and it started to heat up and proceed to overheat. So my fingers are crossed that its air in line or thermostat. No water leaking from the water pump.

K-man

Anyone else feel free to send any other suggestions

captainofiron

sounds like an air pocket

the air doesnt let the coolant circulate properly

tjwalker

Hoping this is not the case, but there is some possibility that the overheat blew a head gasket. That can give the symptoms you are describing.

As for an air pocket, on yours this should resolve itself within 3-4 complete heat up / cool down cycles.

A new stat is never a bad idea, especially as this is a new-to-you vehicle and you may not know how long the current stat has been in there.

If symptoms persist, I would perform a compression test on all cylinders. Low compression on two adjacent cylinders would indicate a blown head gasket.

Good luck and check back in to let us know what you find.....

K-man

Ya im hoping same thing. Im pretty sure its not head gasket. Oil is very clean and as i said before the bottom hose of the heater core came lose ?is was it lose already or was it blown off. After i put anti-freeze in it idled like a champ but as i drove it it started to over heat. Only thing i didn't do is release any air pockets. That's my first thing when i get home. Thanks for the advise i will let u know how i made out

fishtaconc

Top your coolant off ,turn your heat all the way up and remove rad cap let it idle while watching the coolant level filling as needed when the tstat opens top it off again replace cap. fill reservoir to proper level

K-man

Ty everyone for ur input. Problem solved for now, it was air locked. Ill stay in touch if any other problem persist. I love my jeep its the first one i have owned. Its an 03 fully loaded grand cherokee limited with the v8 4.7 H.O. with 137000 miles on it and it runs great i love it. Again thanx everyone