War Eagle

Driving home tonight from my summer class (20 miles)...2000 XJ temp gauge intermittently pings to 250 then would fall quickly to 220. THis ping happened twice, once about 5 miles into the drive and again 10 miles in.Remained at 220 for duration or when not pinging. Almost home and the gauge pings to 250 and remains there for a little under a mile. Begins making knock when I get on the accelerator, sputtering out at low rpm's. Jeep did not want to slow down as I was almost home...after letting off the gas, it would stay at 45 until i braked, like it was on cruise control, which i do not have. Parked it, popped the hood, let it idle for like 10 secs and killed it. Overflow bottle was boiling, but filled up to the line, engine was so hot the oil was burning off the valve cover around the manifold...checked oil dipstick, no milkyness. Any ideas?

OOoooh also.... i did not have heat on the way home. Possible clogged heater core? could that cause an overheat that severe?

any advice as to things to check, things to do...very much appreciated! Tomorow morning I am going to take the rad cap off and see if its breathing through it...if it is, i have a cracked head, right?
If that goes well, check fluids, hopefully good too, then after that cooling system flush?

djb383

Help us out a little.....which list is shorter, what u have done, regarding cooling system maintenance, or what u haven't done.

War Eagle

havent done i guess...it never gave me any overheating issues other than the normal stuff when i wheel, which i havent done in a few months...i only do when its cold because of the heat soak on the trail. I regularly check my fluid levels. I do regular upkeep and preventative maintenance on it.

Turbo X_J

So you knew the engine was over heating and didn't even stop?

War Eagle

Wasnt severe until the last 3/10 mile. With that gauge at a constant 220, i though it couldve been the sending unit

esp002

Have you checked to see if there is weeping coolant around the water pump? I don't think a thermostat would be the issue if water is boiling in your overflow. Also your radiator could be clogged up or something.