dyte2004

jeep cherokee 4l i6 runs at 210 dude water under pressure wont boil at 212 and with the correct mix of antifreeze will also raise the boiling point if you are boiling over at 210 you have a pressure leak maybe rad cap or a blockage somewhere you may even be getting exhaust gas in there pushing the pressure up check you dont have a faulty gauge first
i also have a open system and my pressure cap is on the rad the overflow bottle is actully a expansion tank it has more collant in it when hot than cold as the collant is sucked back in via cappillary action as the rad cools

1987 new toy

All right here are some picks of the swap, You will need to relocate the coil to put the bottle where they put it on the newer models. I removed the plate the coil was bolted to and beat it srait with a sledge, so i could bolt the coil back to it just inverted so that the new over flow tank would sut in there lift up your relay station and bolt the overflow tank bracket in place and then set the relay station where the slot is for newer models fuse box goes. your relay station will be rivited to the inner fender large screw driver or chisle and a hammer will pop the rivet. then bend that backwards and you can use that hole to bolt it to the new bracket, so it does'nt bounce around. Also I bolted the starter cyliniod to the fender for added room.[/IMG]

1987 new toy

cant get the pics on my reply go to my albums and I have the pics there. Let me know if you need anymore if you decide to do it.

darknezz

gj reading my last post...

anyway i took advice again of a earlier post on here and put a hose clamp around the cap to hold it on, its snug now. today i just drove home from work and got some taco bell and it got over 210 just in the drive thru... ITS NEVER gotten near 210 before so I dont know if something got f'ed up or if its just cause summers here.... whatever it is I need to fix it

bobzilla850

Water doesn't boil when its under pressure.

darknezz

omfg I KNOW

i guess ill make a new thread cause you guys arnt reading my later posts

Eli Lilly

Right, because there aren't already 250 searchable threads on cooling problems...

-E

dyte2004

do you know how to test` the fan clutch if not here how spin the fan with the engine off and cold it should free wheel then run the jeep up to temp switch it off and try spinning the fan it should be a lot harder to spin

jeepkid03

Sounds like you might have an air bubble in the system. My 1990 XJ did the same thing. Those plastic coolant bottles are a POS. Its better to just get a new one than try to force a new cap on it incase the threads are screwed. Heres what you do. Park the jeep so that the front end is the highest point. A small hill works good for this or even ramps. Run the jeep for a bit then shut it off. I opened the coolant resevoir cap and some air came out. You can also remove the coolant temp sensor. Be careful because coolant might come out. I advise you to do this after a cold start, not whent he engine is boiling hot. I did this a couple times and topped off coolant as needed.

Worse case scenario you can convert to an open system. Theres a few write ups I've seen on this site, as well as Jeepforum.com, and NAXJA.org.
I'd go for the 3 row radiator from radiator barn. With your jeep previously running at a cooler temp, either your T-stat was broken (i've seen them bad right out of the box) or your coolant temp sensor is bad.