alright guys i need some help. I just bought a 99 XJ, it was pissing antifreeze from the radiator pretty bad. So i through a new radiator in it. I drove it all the way from grand rapids back to spring lake it overheated once and i stopped at a gas station and i didn't have enough coolant in it topped it off and drove the rest of the way no problem. I went out there and played with it a little bit the day after i got it home and it decided to overheat again. it slowly goes up to 210-220 and then jumps all the way up 250-260. suggestions? i replaced the thermostat, put on a new temp sensor and did a fresh oil change.

Did you make sure that you have ALL of the air out of the system? What is the shape of the water pump?

Is the electric fan coming on? Should kick on at I think 219, or when A/C is turned on..
Hows the fan clutch?

Theres not much to the cooling system...

Thermostat, Water Pump, Radiator, Fan(s), Sensor for e-fan, Fan clutch. Heater core.

I am not one for throwing parts at the yeep, But you need to keep cooling system up to par,

Since you just got it, Why not throw a new water pump at it, Very e-z to do.. and you will know for sure it is good..
Ant..

how would i know if the water pump is gosing bad?i believe i got all the air out of the system. i replaced the thermostat, the radiator, the temp sensor the fans work great.

i also flushed the heater core some nasty brown stuff came out. i also i have no heat.

replace the water pump.

also if you replace the heater core do the evaporator core while you're in there.

Well if you are still over heating, Mine as well change the water pump, I just bought a 99 xj as well, The water pump was so rusted there were no fins at all, 100% rusted off..

How do you know the fan clutch is good?

If after changing water pump, Still over heating , You could have bigger issues.. But hopefully water pump swap will do it..

Just a thought

Ant...

Fan shroud intact/in place?

That "nasty brown stuff" could be the remains of the water pump impeller.

i was fixing to say... nasty brown stuff usually equals corroded water pump fins... pull it!!!

I hope you did flush the block 3-4 times to get all the rust out of it also. If the heater core had that much rust in it I suggest another round of "Good Cleaner" not the cheap junk going through everything, heater on high heat setting also. You want a lot of cleaner to flow into the heater core, drive it for 1/2 and hour then drain, see how much more rust comes then and flush till all runs clean again.

Don't know if you did or not but while your at it might as well replace the radiator hoses and heater hoses if they are cracked or less than pliable for good measure.

Water Pumps are cheap you might as well replace it and know you did a complete job.

Is it still loosing coolant? The pump impeller may be gone but it's not large enough, even when completely dissolved, to turn 3 gals. of water brown/rusty.....brown/rusty water in the cooling system is from the cast iron block/head internally not having enough rust/corrosion protection in the coolant due to years of neglect. Cast iron naturally rusts when unprotected.

i think the guy that had it before me put some of that stop leak BS in it to try and stop the radiator from pissing fluid. I think that what the brown **** was because it didnt look chunky it was just a nasty color. im going to flush the whole system right now and see what that does for me then im going to do the water pump next.

When the stop leak is used according to the directions, it does not turn 3 gals. of water brown/rusty. Be sure to flush the block/head separate from the rad and separate from the heater core.....in other words, the 3 components should be flushed separate of each other.