coolant cap hiss/coolant dribble from same

[sharky88]

my 88 pioneer (4.0 2wd auto) coolant cap emits a hissing and coolant in small but noticable anounts and is dripping down the lower hose on the plastic tank onto the black cannister below and the wiring bundled below. last nite after the jeep fully cooled the tank was less than half full. after driving for 30 mins today about 15 miles slow (air temp outside 50 deg and no heater running) around on surface streets it is almost full when i parked it today. last nite i cleaned the cap bottle and noticed the bottle has shifted from the bracket and the nubs on the tank had slipped out and the tank was not secure. there is a depression on the hood insulation where the cap is making contact.I REMOVED THE CAP retightened it . so today after the drive it leaked a bit of coolant but was hissing so low i had to put my ear it to hear it. should the cap only be opened when the jeep is cold? was it simply not tightened properly? and or the cap is crapped?

it runs at 210 even lower when you get out of stop and go on surface streets. at 265 miles (xmas eve afternoon) since i bought it it started to creep just a bit over 210 (almost to 220) as i pulled up to parts store to get a new cap for the bottle as a precaution after reading the posts here(had been in heavy traffic)! mech told me if it goes over 210 pull over shut it off go under hood. i did and checked the cap. nasty hissing and the coolant had been dribbling out and down in small amount.

the jeep is new to me (3 weeks) has 197000 recent rad thermostat(maybe 2yrs 15000 miles, dont know if 160 or 180 deg) and hoses. this jeep was maintained by first owner but the second his son had it from 170K to 197k and seems to have only adressed issues when he had to. i am very concerned after reading almost every post here on overheating and anything that can affect overheating that there may be serious problems( head gasket/ cracked head). there is no coolant in the oil( on stick or at vc cap ) no oil in plastic tank checking after every use. i have changed the oil filter cap rotor plugs clean entire air cleaner. the oil had no water/coolant. the cap was crapped and since replacement it hasnt stalled as it did on first three days after cold starts less than mile from home each time. the cps has about 1000 miles on it. the idle is slightly eratic and i am concerned this is a sign of coolant entering the comcustion chambers. the plugs were not fouled and had slight whitish on ends but i read this means no leak into head as it would wash it off. i assuming the o2 sensor is crapped as it passed cal smog with very low readings except in "NO" LOW SPEED almost reading at the fail level. i understand an old sensor will cause it to run rich with the idle being affected.

before i even consider replacing the ex manifold(mech says he hears it leaking) or the rear main seal which is laying A drip a day( mech says it will go fast) on my garage floor or a fuel pump (he says its 'buzzing') i want to know if i am looking at a minor cooling problem(new cap and or bottle with expert bleeding of system or a new thermostat or even a bad water pump) or a persistant nightmare like a clogged block from the po dumping in some rad sealant before doing the rad and or carcked head/blown head gasket.

i read and reread the posts on bleeding the system and how air pockets can cause overheating. WHAT IS OVERHEATING on this truck? i have never run it for more than 2 hours straight and that was midnite road test on freeway . is the seal on the cap bad? i intend to get a cap at a dealer tomorrow and had wanted to get bushings for the sway bar etc to get rid of the old cracking rubber but..........

i have no experience with closed cooling systems having avoided them like the plague. in 30yrs ive owned a 73beetle 2 pre '81 4cyl bmws so the closed sys/coolant bottle seems to be a very real pain.

maybe it could be driven it around for the short around town light hauling and just live with it until it starts to get worse but i wont stick my head in the sand. i cant let the wife drive it at all until this problem is fixed and maybe i shouldnt either. we want to keep it but not if it will be a money pit because of clogs in the block ,cracked head and the other issues if they are real or just oversell.

any guidance will help. tia i need to sleep!

[capt. apathy]

your in the first stage of 'jeep overheat syndrom' and it will only get worse.

you need to replace the cap (and if this is the first time, then the bottle too as they changed them and the new caps won't seal on the old bottles. they barely seal on the new bottles)
and it's time to do a serious flush on the radiator, it will continue to get hotter until you get it all cleaned out( I had to flush mine several times with the long term prestone flush.)
when you fill it back up make sure you get all of the air out of the system(no easy trick), about the only way I've found is to parkit front down on a very steap hill, then remove the coolent temp sensor on the back of the head to let the air out as you fill it. fill until coolant comes out, and then squeeze the upper radiator hose to try to get as much air as you can out of it and into the head (and out the hole).
also check your computer readings and make sure your cts is working, they can get stuck at a cold temp and you will constantly run in warm up mode

it sucks and this has got to be the worst cooling system design I've ever seen, but after you are done then you will be a fully initiated jeep owner.

I'm sure your exaust is leaking, (the next most common problem) make sure they don't put the stock cast one on or you'll be replacing it again soon.

[sharky88]

thanks for the input/advice.

can i drive it very short distances since it runs at or below 210?
should i use a baster to pull some coolant from the bottle?
is opening the cap after driving putting air into the sys?

if the cap should never hiss(indicating loss of pressure) then this will be a recurring problem since anything plastic will fail when exposed to so much heat and pressure . truly a nightmare.

still looking for a shop manual and haynes but none around me locally. there are so many cherokees around here( 2 just outside my window on the street every nite and a cj or 2). you cant drive down a street without seeing cherokees every block.

now the cap/bottle i have cant be the original as i have an 88. didnt see any chrysler parts# on it or their emblem so should i assume it is an aftermarket? will a dealer cap fit? the corner parts store has no cap alone but i believe they sell it with a bottle. should i go dealer on this?

to put a new bottle on seems easy but the amount of coolant i should be filling it etc. is unknown to me.

if i put on a new bottle then pour in prestone coolant to fill the bottle half way should i then drive to the nearest hill park it facing down hill. do i have to wait for the engine to cool before opening the air escape on the cts? ( i read here to use teflon tape on the cts before reinserting)

at this point i just want it to run in spec then i can get serious with flushing/reflushing once i see that i can do the burp.

i rent parking in the apt bldg i live in and have been getting
away with oil changes and quick repairs and detailing(getting the dog hair out from the po) but draining volumes of flush/coolant must be messy. i assume you use a bucket under a lower rad hose to catch the coolant as well as a drain plug. i have read your posts on your flushing reflushing but just cant visualize this procedure.

i hate the idea of paying a mech to do a flush cap/bottle only to have him leave air with the result that i fry another bottle or get set up for an endless series of flushes at great expense if i pay a mech or risk damaging the system worse by my inexperience.

is it common practice to premix the coolant with water in a container(2 liter soda bottles 50/50) then pour that into the bottle to get it into the sys ? i read you pour into the upper rad hose.



as for the ex manifold mech said it was tiny crack he can only hear barely adding most wait till it gets louder before replacing. but he added the leak screws up the o2 sensor functioning resulting in a rich mixture(poor mileage for sure) and higher idle( i have gauges but no tach!). he says if i put in a new o2 before a new manifold it will just ruin it. he added i shouldnt use say any bosch9universal or model specific) as a replacement but a only a dealer part.( online jeep supply has a three wire for 50. mech wants 100.!

i saw the new design with the expansion features on the outer pipes. also the old desisn in ss without the expansion design as well as the cheap units painted black. this job i dont think i can do. the mech wants 400 for manifold 450 to install. another mech said he would weld it if possible but that seems like a waste of $$$$ for labor to remove weld reinstall as it will likely leak and how can he guarantee a weld job on an old manifold?

again thanks for your help capt. i want to keep the jeep but this closed cooling system seems so flawed i fear i will not be able to deal with it myself and cannot afford to pay to have it fixed over and over.

[sharky88]

capt.
after rereading your correct me if i am wrong:

1. at the very least my cap is crap replace it.
2. there is air in my sys so get it out
3.at some point the sys must be flushed as preventative/curative step as new owner of a used jeep
and to rule out or diagnose other problems

if after i get the new cap( i will wait for sys to cool) and screw it on and i still get a leak from the tank at the hose on the bottom its a bad tank(aumming the hose is on tight and is not bad(looks new feels new)

then i follow the advice you gave on basic burping and/the flushing. have to work out the way i will deal with all the coolant mess but i cannot be dependent on a shop wwhen i have a high miles cherokee and so far i have done alot but only things i am familiar with. it is getting up the guts to disable the jeep by emptying the cooling sys.

thanks so much. i hope to laugh at this first syndrome encounter 20,000 miles down the road.

[capt. apathy]

my cooling system adventure came in august. I couldn't drive it more than 10 miles without overheating, couldn't afford to have it down, or pay a shop to fix it.

so I drained it and removed the thermostat. I then put in the prestone super flush (you leave it in for 3-5 hours of drive time).

then when it was time to drain it I pulled the top hose off the radiator, jammed the garden hose into it and let the water run out the top of the radiator. the reversal of flow seemed to losen a lot of crap from the radiator. while it was flowing I also ran a small hose down into the radiator and had it syphon at the same time, this hose would pull a quite a bit of rust and other debris from the radiator.

I did used the chemical 3 times, about a week apart. in-between I just ran water in the system, and back-flushed it with the hose once a day.

it was a pain, but it didn't have me down for long at any one time and didn't take much cash out-of-pocket.

I just kept at it and payed attention to how long it took for the temp to come up, when it started taking longer to heat up and I was getting less crap out in the flushes I decided it was good enough and switched back to anti-freeze, so far I've had no more problems. the cap still steams a bit when hot but I'm noticing no coolant loss so I just ignore it.

I got the bottle from the dealer (about $30, $11 for the cap). if you look in the bottle you'll see a post sticking up (looks like a small plastic pipe), the 2 halfs of this are cut to different levels, the low half is add, the high half is full.

it's suposed to run hot (200 or so), the stock thermostat is 190. I put a 180 in after all the flushing was over (still a little nervouse about over-heats) but now it doesn't get quite hot enough so I'm going to have to put a hotter one back in.

[sharky88]

i understand, these jeeps run hot and the stock closed sys s#x .
just came from the dealer with a new cap. 13.72...(bottle there is 52+tx). 20 min drive slow moving traffic 2 miles at 55mph and it rose to 210 but no heavy stop/go. runs at or below 210 as low as 190! (last nite i cleaned cap/seal threads on bottle and tightened it.) on return from dealer ran the same. after opening gargage door while jeep was idling in P to back in temp seemed to jump to 215-220 at shut off. now no loud hissing or significant dribble very little but it shouldnt do it. very low i mean very low sound but there was fresh coolant there at the bottle at the baseof the threaded opening by the bottom edge of the cap. some at the area below the bottle.

thanks again for your guidance/advice.



paying a shop for basic cooling system maintenace will not teach me about the jeep closed system (and other components/systems)and will not help me if i break down on the road .

capt thanks again for your guidance/advice.

[capt. apathy]

btw- for others with the over-heat problem. I think I have something worked out for getting the air out of the closed system. I should have it worked out in the next couple weeks and after I test it out will post pics of the solution.

[Bmaintz]

Honda Accords have a Value on top of the thermostat for bleeding out air pockets.... Was wondering if you could do the same for the 4.0 engine????
Bob

[redteamleader]

love the coolant sys in jeeps .... i always carry a roll of plumbers teflon tape this helps extend the time between cap & bottle change . just a few wraps on the bottle thread works great and you can keep adding unti the cap no longer fits.

[BCBlues]

Ok folks, this is what I did to my 1988 Jeep Cherokee Laredo's cooling system, and I have not had any cooling problems since. No more over heating, no more leaks, no more problems. This works, and cures the whole problem. Check it out.
http://www.automotiveforums.com/vbul...d.php?t=206558