ok just so we're clear, i'm a rodeo guy from the "other side." my buddy's 89 cherokee just started running rough only when cold. i put in new plugs and rotor and cap but no joy. #1 plug was covered in some hardened deposit like i've never seen in 30 years of working on cars. <img src="/forums/images/graemlins/confused.gif" alt="" /> now it's running bad all the time and i believe he's sucking antifreeze. my ? is, does the intake manifold have passages for coolant? is there a "usual suspect" for this type of behavior. i've never worked on a jeep, though i am impressed with how they hold up. i was actually looking for a cherokee when i bought the rodeo, so i really am a nice guy.....any thoughts? direction to run? tia <img src="/forums/images/graemlins/patriot.gif" alt="" />

Dude if you are losing coolant park on concrete and wait a couple of hours then crawl under with a light and FIND the leak! It will be dripping or a spot or two of coolant will be near the leak.
Engines do NOT "suck" coolant!
You could give a little better description of the way in which the engine runs "BAD".. Does it pop and crackle? Does it run up slowly? Does it idle really rough and not smooth out till 2500 or so? C'mon and give us a better hint to go by.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

it misses and chugs under load. it used to do this only when it was cold for about 15 min; now it's all the time. no antifreeze is dripping on the floor but the level keeps going down. i'm thinking possible head gasket but wondering if it might be IMG since it used to get better as it warmed up. i'm basically wondering if ther is a "jeep thing" that this rings a bell for.

Ok dude think of it thisaway!!! The compression has more POWER than the coolant pressure.. If you have a headgasket leak into the engine the compression goes OUT INTO the coolant and you get spewing all over the place! FORGET about a headgasket failure!!
If you are loseing coolant it is trickeling down the outside of the engine..SOMEWHERE! Crawl under it with a light and look VERY closely for ONE drop of coolant.. You do not have to have a puddle under it. Perhaps it is only dripping a bit while the pressure is high? Perhaps it is a leak HIGH on the radiator and only drips while the coolant is waaaay up there? You MUST look for the leak with your EYES.
As for how it is running, TUNE it up and see what happens.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

Ok BJ I must disagree a little here. Now I do agree while running the pressure in the cylinder is absolutely higher than coolant pressure, but when the engine is not running the pressure in the cooling system is higher than the pressure in the cylinder. I had 79 Honda Accord that had a leaking head gasket in cyl #2 and as long as I drove the car every day it would keep running, but if I let it sit for more than about 3 days enough coolant would leak into the cylinder that the engine would not turn over and I would have to pull the plug and crank it over to let the water out before it would start. The really quick tell tail if there is a coolant head gasket leak, when he starts the jeep does it puff ôwhite smokeö (steam) out the tail pipe for the first minute or so, what does the coolant in the radiator look like, and what does the oil look like. Eventually it will get to the point where there is oil in the water and water in the oil if the head gasket is leaking.

Now all that being said, to me it does not really sound like this guy has any of these problems. It sounds to me like his jeep needs a tune up.

Sean

BJ is right on the head gasket,dont worry about it.as for the coolant leavel conatantly going down mine does it also and have yet to find a leak.just have your freind keep an eye out for it. you can also place a piece od cardboard under the engine at nights to see where and if any antifreeze is dripping,as well as pressure test it.
as for the chugging and such test the o2 sensor,my jeep did the same a couple years ago.
here is a list of things that should be checked and cleaned,repaced or repaired as needed.

iac-idle air control should be removed and cleaned from carbon and other deposites.
throttle body should also be removed and cleaned.
check the fuel pump ballast resistor that is located on the left front fender towards the front.it is an off white block with 1 screw holding it in and 2 wires hooked to it.remove it and look at the back you should see a rope about 1/4 in dia with wire around it.make sure it isnt loose or damaged.heck it is only a few dollars i would get one.espeacially if you see the rope.the new ones are sealed in the back.
check the coil to see if it is putting out enough spark.or as BJ says replace it every 20k or so.
i would also run an oil system cleaner through the engine.gunk makes one that comes in a silver can like the old 1 quart oil cans that works really well.
i mentioned cleaning the throttle body and iac so i would go ahead and do a fuel injection service as well.what that boils down to is an o2 sensor safe carb cleaner,an additive for the fuel tank and if you can find them they make a can of cleaner that hooks to the fuel rail wher the fuel hose goes in to clean the injectors,valves and combustion chamber.
i would really start with the o2 sensor though with the rough running,and extra deposites on the plugs points to an o22 sensor that was slowly failing now compleatly gone.

I have never heard anyone actually recommend this gunk engine cleaner before. I have heard several bad things about it, and that it is basically just diesel fuel. Me personally, I would never put anything in my engine oil other than oil. The only way I would ever consider putting anything in there that was not an oil was if I was to pull the oil pan afterwards and let it all drain out, since during an oil change the oil never all drains out; you can have up to half a quart left in the pan in most vehicles after draining. Just my 2 cents.

Check the other items recommended first, O2, IAC, throttle body, etcà

Sean

Maybe so Sean... But while you were driving, it was puking it's guts out! Headgasket to cylinder leaks fill the coolant passages and radiator with compressed gasses.. after a few minutes or miles the puking starts and the radiator empties itself.. and overheating is quick under these circumstances.
<img src="/forums/images/graemlins/smile.gif" alt="" /> I did get a big grin over you draining the cylinder before starting... Thats pretty hard headed.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

i personally use the gunk every so often to clean out the engine(every 30k or so) i never had any ill affects from it. but as you said some stays in. but you have to figure a 4.o holds 6 qts you drain a quart before you put the gunk in. so you still have 5 quarts to dilute it. then after draining and replacing the filter you fill it back up with 6 qts of oil so it dilutes more.

I see no reason whatever to clean what don't need cleaning inside the engine. I would be scared as hell of chunks of crap floating around and into my pump!
We know what the inside of a 200K engine looks like... I think they should be left alone.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />