cooling system problems

Alright, I'm officially at my wits end. I have an 87 cherokee and had been having problem overheating. Here's a list of what I have done:

new CSF radiator because it the old one was bone stock
new waterpump because I have the autozone lifetime warranty and was free
new factory 195 thermostat
new fan clutch. Not sure the old one was bad but was also bone stock, so wth
new hoses because old ones also stock and really needed them anyway
new bottle and cap
new heater control valve because I broke the old one when replacing the hoses
Before changing the above I drained the system, filled with straight vinegar, ran for
a day and then flushed, filled, ran for awhile several times until entirely clear.
I also flushed the heater core per the link I found on here previously.
Refilled with 50/50, burped the system with the nose parked downhill and removing temp sensor. Runs fine for awhile but after getting on the highway, the coolant would expand to the point that it filled the bottle full and then would pop the cap loose and overheat.
Finally got tired of this, went to the boneyard and got a bottle and cap from a Dodge Intrepid. Was an easy fit with an adapter or two. Now instead of popping the cap and overheating, it fills the bottle full and then starts pushing it out the overflow line and continues this for as long as you run it. Won't overheat from this until you have lost too much coolant. Here's the wierd thing, and I remembered it doing this on the XJ bottle too: after shut down and cooling off even over night, the coolant never returns to the block, radiator, ect. If I park it nose down hill and remove the temp sensor, the coolant will drain out of the bottle and I can fill the system to the proper level. Why do you think the coolant won't contract and return back to the block, rad, hose,etc?
I haven't had time yet to take it to a rad shop and get the coolant sniffed to check for HC but does this sound like a possible head or head gasket problem? I can't understand why the coolant is "backing up" in the bottle and not returning to the block.
Any ideas?

i had the EXACT problems you have!
I ended up getting rid of the bottle set up(you could try the volvo conversion)
and i removed the air conditioning condensor because it was WAY more plugged up than i thought.Hasnt overheated yet.

Whats weird is that your coolant doesnt return to the block.I would make sure that you have unrestricted hoses, especially the smaller one that runs along side the head to the water pump from the bottle mess.I only say that, cause i used a leak sealant years ago to try to fix a rad. leak and it ended up plugging the small hoses.

Have you noticed oil in the coolant or vice versa?

You could also drill a small pilot hole at the 6 and 12 o clock position of the thermostat to try to bleed more air out

No oil in the cooler or vice versa. When you say yours had the EXACT same problem, do you mean that coolant stayed trapped in the bottle?

i might be wrong, but im going to go with air in the system. anouther way to bleed it if you dont want to drill holes in the tstat(the easy first time way) is to start the jeep, and with the heater on high, let it build pressure, and then pull the RETURN line from the heater core off just far enough to hear the hiss of air comming out, then put it back on.

Becarefull, you will burn the hell out of yourself if you do this with head in ass or buddy bull shitting with you, trust me. That water comes out hot and fast. Once you get it bled down, it should stop doing that crap to you.

Of course, if you have plugged hose, or a stuck tstat(or backwards) or anything like that, you will still have problems too.

oh, and correct me if im wrong, but your year of jeep should have a closed cooling system right? Do you have anything open, or is everything on lockdown?

Yes it is closed system and everything is tight. If there was air in the heater core could it stay trapped when I bleed it mucho times by pulling the temp sensor with the jeep steeply nose down?

i would get the coolant "sniffed" we had a jeep in the shop awhile back that was doing the same thing. it ended up being a cracked head causing compression to push the coolant into the bottle. you can test this by putting air into the cylinders and watch for bubbles in the coolant. also listen for the air escaping.

I just had the exact same thing happen - partly. earlier this year I bought a new coolant expansion tank and cap because the old tank was cracked around the neck where the cap screws on. I didn't think much about why this was and just replaced it.
So now, a few months later and I stop the jeep and gush, there's coolant pouring out the cap....W....T.....F.....??
I figure I didn't tighten it down properly or something so after it cools I remove the cap, put it back on carefully and tighten it down. i noticed that it did not want to thread on properly at first but with a bit of work I got it on square and it snugged right up. went for a drive, stopped and gush - coolant pouring out all over again....W ....T....F...?
I take a closer look and I see that the cap has been pushed up - it is no longer snug against the tank. - excess pressure? why? how?
Then I see it - there, on the hood, the sound barrier insulation is all shredded right above the coolant tank cap and the paint underneath is worn away to bare metal. That's why my previous tank was cracked around the filler neck.

Every time I shut the hood, it would make contact with the coolant tank cap ON ONE SIDE ONLY and force it to be skewed on the bottle. this has destroyed the threads on the plastic coolant bottle and so it no longer can hold normal pressure.
I know many people have complained about this closed cooling system but my turbo Audi has the same kind of system and it has never been a problem - there have been problems, but not because of that type of system
Could it be that all of these problems are because of the hood contacting the coolant tank?
The tank is mounted on a metal plate that I am going to lower tonight (which I can do now that the ABS pump is gone) and see if that makes any difference

As for why your coolant is not returning to the engine....sorry, can't help.

slider said:

i would get the coolant "sniffed" we had a jeep in the shop awhile back that was doing the same thing. it ended up being a cracked head causing compression to push the coolant into the bottle. you can test this by putting air into the cylinders and watch for bubbles in the coolant. also listen for the air escaping.

Click to expand...

You can also "sniff" using the smog machine to detect CO (carbon monoxide). If it is a cracked head exhaust gases will get in there and cause excessive overheating. A radiator pressure tester would also indicate a very high and creeping up to dangerously high pressures...be careful here...hot, boiling coolant can burn you.

fuzzydog: I don't know if you have already bought a replacement tank/cap or not but I had bot one and four EXTRA caps from quadratec and every one of those caps would pop loose. The one that shows in thier catalog is "star" shaped (but black) like the original factory cap that I had no trouble with for 15 years (my rig is an '87 I bot it in 1989). The factory original cap was "star" shaped but was white in color. To get the system to hold pressure I used to take a pair of channel lock pliers and really put the mojo on the cap and it would not "pop a thread". My son finally broke the cap a couple of years ago and we got a replacement from the stealership. It was not star shaped, and you could not tighten it all the way down BY HAND without it "popping a thread". Then I got the replacement bottle and caps and although a couple of the extras were star shaped, not one of them can be tightened all the way down. Now granted I'm sure the extra pressure from my tank overfilling when run on the highway probably is the main cause of the cap popping loose, but I'm telling you the new tank/cap combos are worse than the original and it would be hard to convince me that they will even hold 13 lbs of pressure. Thats why I went to the boneyard and got one of the Dodge Intrepid tanks with the cap. Cost 10 bucks for both and it CANNOT pop the cap loose because of the way it's made, and with a couple of hose adapters is an easy fit. If you haven't replaced yours yet, that's what I would go with. BTW, you have to unbolt/remove the metal shelf. Good luck.

AlohaBra:
What is a "smog machine"? And where could I get access to one or a radiator pressure tester (other than taking it to a radiator shop, etc.)

Thanks for the headsup on the crappy replacement tanks. I haven't got the replacement yet (small town, eh) but I will look into the intrepid replacement.

there is a company out there that makes aluminum tanks for these.
on my 89 i filled it right through the top radiator hose and then put everything back together except for the cap. let it run for awhile after it heats up, some puking of coolant is fine. I would then put the cap on and spray down the radiator real good to get all the unseen mud out of the radiator. Never had a real problem doing it this way many times. Also 230 on trail runs with these 4.0's is fairly normal. I have the aux fan and it will usually stay under 227 on the extreme end of things. Also the coolant is supposed to stay in the bottle.

update on mine - I ended up getting the new expansion tank and a cap - I wanted to go wheeling on Sunday and didn't want to mess around with making the intrepid thing work. Anyway, I suspect I only needed a new cap - but what's done is done. The old cap would not thread cleanly onto the new tank or the old tank. But the new cap threaded cleanly onto both tanks. i installed the new tank and new cap, modified the mounting plate so it is a bit lower and all is well. Got the temp good and hot in the driveway and no leaks. went for a spirited drive and all is well - then went wheeling in the snow on sunday and got quite toasty and held the pressure well. I'm positive that my problem was because of the hood hitting the cap. I guess time will tell....

update on mine - I ended up getting the new expansion tank and a cap - I wanted to go wheeling on Sunday and didn't want to mess around with making the intrepid thing work. Anyway, I suspect I only needed a new cap - but what's done is done. The old cap would not thread cleanly onto the new tank or the old tank. But the new cap threaded cleanly onto both tanks. i installed the new tank and new cap, modified the mounting plate so it is a bit lower and all is well. Got the temp good and hot in the driveway and no leaks. went for a spirited drive and all is well - then went wheeling in the snow on sunday and got quite toasty and held the pressure well. I'm positive that my problem was because of the hood hitting the cap. I guess time will tell....