ok i just bought a 97 cherokee off of a "friend" two days into driving she overheats i flush the system and get nothing but black and brown liquid and the radiator has clumps in it....replace rad tstat and flush whole system runs like a dream below 210 all day in the woods and out driving on the highway i step on the gas a little to pass someone about a minute later i smell anti-freeze park it up and see my freeze plug is pouring out coolant now my question is is this a sign of a bad head gasket or could i have not burped the system enough when i fixed it and caused an air bubble in the system to pop it? ive already put more work into it in a week than i planned should i fix the freeze plug and cut my losses or is it nothing to be worried about?

 

Air wont cause a freeze plug to leak. most likely it rusted out from all the junk in the system. Replace all the freeze plugs and keep goin, has nothing to do with head gasket. Flush your heater core real good to, itll probably be clogged from the junk that was in the system,

 

As far as I know, coolant coming from the freeze plug is not a sign of blown headgasket.

 

thanks im gonna get a kit and replace all of them i didnt even think they were beat from all the crap that was in the system i actually did a bypass on the heater core becuase of how bad it was thats something ill focus on in september haha

 

Yeah, Like mentioned above. A bad head or head gasket will not cause the freeze plug to fail. If you had that much crud in the cooling system that will cause the steel plugs to rust out and fail. When you replace the freeze plugs make sure to buy the brass plugs and not the steel ones. It sounds like you will have to do several flushings of the cooling system. Flush the system until you get clear water coming out. Then put it back together and run it for about half an hour let it cool and flush it again. Don't bother putting in coolant in until you get all the crud out. You may have to do this several time. BTW, Flush the radiator separate from the engine. Also on an open cooling system you don't have to burp the system like you do on the closed system. But you do have to recheck the radiator level for a couple of days to make sure the level is good. Good luck!

 

I had a very similar problem withover heating. Thought that maybe the head gasket or the head was cracked. Something I was told is that when you're flushing with cold water the thermostat will close trapping all of the loose gunk with the thermostat. I was told to flush without the thermostat in.

 

The t-stat should be closed by the time you are ready to flush it anyways. As soon as the engine cools the t-stat should closed unless it isn't working properly. This is why you will have to remove it before you try to flush or you won't have any flow.