Have a few issues going on. Was hoping someone that has had these problems would chim in and shed light. So I have had problems with the cylinder 3 misfire due to the heat soak problem. My cherokee is a 2001 sport. Usually after I run around town and stop somewhere I'll fire it up and it runs crappy for 30 seconds or so then clears up. Usually get a cylinder 3 misfire code to pop. But lately it's even worse. Completely falls on it's face. Can barely get the idle to come up. And the check engine light flashes an few times. When I read the codes I get cylinder 1,2,3 misfires. Along with a random misfire. Anybody else have that problem? Ok also I checked my antifreeze today, it's like a deep rust color. When I bought it almost 2 yrs ago same thing. Radiator was bad. Replaced the radiator, hoses, thermostat and water pump. Flushed the whole system. It was clean. Now it's back to what it used to be. And today I noticed there was a thick sludge buildup in the filler neck. I took a magnet to the gunk and it pulled to the magnet. So I'm kind of worried about that. No noticeable flakes of metal. But it's a blackish color almost feels like fine sand between your fingers. Any ideas on that as well? Thanks guys for any help/advice!

 

I guess ill be the first to say it, seeing as you have an '01, i would check to be sure the head is not cracked

 

Would there be any obvious signs if it were cracked?

 

Yeah, everything you mentioned in your first post.

 

Lovely!! Lol. Well... It's been running strong. Aside from the occasional hiccup from the heat soak issue. Guess time will tell...

 

Any sign of coolant in the oil?

 

Nope oil is clean...

 

When it comes to vehicle problems, the saying isn't "Time will tell.", though that's true, it will.

The correct saying is, "Time will trash."


Leave it alone long enough, and you can turn a $10 repair into a $100 repair, a $100 repair into a $1000 repair.


If you have a cracked head, you can trash the engine if you don't take care of it.

OR, you can fix it before you trash the engine.


Your choice, of course!

 

YEP, coolant leaking into cylinder 3 or 4 and causing a misfire at startup is a sign of the infamous cracked head. The PO may have tried to stop it with sealer....that would explain the gunk in the radiator. When you flushed it you probably removed the sealer (temporary fix) and now it is leaking again. Possibly could be a head gasket but that is wishful thinking. If oil pressure is good a new head may be the remedy. sorry.

 

Well actually since you mention oil pressure. I recently did an oil change. Ever since doing that, my oil pressure drops really low when idle. To the point where the check gauges light pops on. Only does this after the jeep has reached operating temp tho. And no I do t have a fram filter. It's a napa gold. That was my first thing I did to see if that fixed the low pressure. Never had a problem with pressure till this last oil change. The mid fires are on 1,2,3 cylinders. Never the 4th. Yet.

 

I had a similar issue you are having. Have you done a compression test yet? I was having misfire on cylinder number 3. Pulled head and cleaned the head and block along with replacing valve stem seals. I'd say do a compression test and see what your dry and wet compressions are. Also what does your spark plugs look like?

 

Any loss of coolant? When you shut it off (if its a crack or head gasket) coolant could be seeping into the cyld and cause a misfire upon start up until it burns the coolant back out. Look at your plugs to see if any are cleaner than others, also compression check will help diagnose the problem.




I must type slow

 

I had this SAME issue. Like sandy rust in my coolant. Constant heat soak misfires and flashing check engine light. I had overheated my jeep and this ultimately was my root problem. Cracked cylinder head. Got it fixed and no more coolant loss. Took a few coolant changes to get a consistent clean coolant color. But I still get the dang "PO303" code on hot restart. Homemade heat shield over a new factory shield seems to help a lot.... (got shield at dealership for $3.....ask them to look up exhaust manifold (if I remember right) heat shield under RECALL parts). That annoying injector heat soak drives me nuts!

 

Have not checked compression yet. Plugs are new as of a few months ago. I'll check them to see what they look like now. So far no coolant loss either. It's always at the same level.

 

Maybe its not the same issue as mine was. If you have no coolant loss nor oil level changes then its beyond my experience level. Sorry dirt_biker_guy for jumping to thinking your problem was the same.


BTW your in ridgecrest area and a dirtbiker.....did you ever make it out to burrow Schmidt tunnel before the BLM closed it? (I don't mean to hijack your thread but I practically lived up there because my family knew and loved tony seiger)