i have a 99 jeep cherokee sport.i put a whole brand new coolong system in and changed the freeze out plug twice.Now after all that i popped out again and i dont know why.can someone tell me why this is doing this lol thanks!!

 

If you mean the block freeze plugs they have to go in STRAIGHT.... There is a tool at NAPA or Harbor Freight that can help...

 

I changed my freeze plugs a while back and I've never had any problems. Did you use sealant to keep them in place? I used a socket to push them freeze plugs into the block. How long did you allow for the freeze plugs to settle before running the engine? I'm just wondering because I havn't had ay issues since I replaced the freeze plugs

 

Core plugs must go in straight, or they won't stay.

They're driven hard enough that "sealant" isn't usually required to keep them in place (but it won't go amiss to seal imperfect bore surfaces anyhow, so do use it. I like RTV Black.)

If the plug goes in easily without needing to be driven, the bore is hooped. You can try an "expandable" plug (rubber plug with expansion nut - I've had mixed results with these. Plenty of RTV to make sure it stays put in this case won't go amiss - you can't expand the thing enough to make up for the force that is usually used to drive them in place.)

I've also done the 'strap' approach to retain plugs on maximum-effort engines where I've set up high-pressure (>16psig) cooling systems - you cut a metal strap from sheet stock (I use .060" aluminum,) and drill and tap for two small machine screws on either side of the core plug in the boss. The plug gets driven in flush, the strap placed, and the screws installed and retained (LocTite #222 or fingernail enamel will work neatly - I don't suggest LocTite #242 - the screws are usually too small.) This will work best if you bend the long edges of the strap upwards just slightly (making it a shallow U shape) and putting the flat part against the core plug - this will make it harder to bend the strap and push harder against the plug in the bore if needed. I've most often formed my straps around short lengths of square bar stock to form the "U" shape. (I may still have some of those pieces in my toolbox, in fact. I've got a lot of oddball tools I've made over the years...)

But, first and foremost, check to make sure the plug isn't loosening in the bore - corrosion can cause this. I do not know if oversize core plugs are made - if they are, you can open up the bore past the surface corrosion using a brake cylinder hone to get .010" or so - flush the iron particles out with carburettor cleaner, wipe them up with a rag. Finish the bore with 120-180 grit stones to give you a smooth surface to seal against, use RTV whenever you install core plugs in any bore.

(They're properly called "Core Plugs" - if it gets cold enough that your cooling jacket freezes and pops a plug, you've probably cracked a block anyhow. The ports the plugs are driven into are remnants from finishing the casting - the sand cores are flushed out through the ports, the ports are machined to size, and the plugs driven in. The only engine block casting I can think of that doesn't have core plug bores is the third-gen Hemi casting (5.7L, 6.1L, and 6.?L.)