Overheating one more time

[ranchand58]

So my 2000 XJ, with the notorious overheating problem is at it again. Already replaced the radiator, thermal fan clutch, water pump, thermostat, fan relay, electric fan, and coolant, coolant temp. sending unit and oil pressure sending unit. All is well for a couple weeks, then out of nowhere the temp guage pegs in a few seconds and it is really hot. Kill the engine and let it cool 10-15 minutes. Start it up and no problem? Drive it home and all is well.

This is what I'm trying....
Removed the top rad. hose and IT WAS EMPTY. Filled it up, all seems to be ok for another 8-10 days. Then, repeats all over again.
In the meantime, noticed oil pressure was getting low, and check gauges light came on. I'm currently changing the oil pump, let ya know bout that.

No water in the oil when drained, no water seeping anyplace I can tell. What the...guess I'll pull the new thermostat and check it on the stove.

The new elec. fan has a blue and black wire going to the harness plug. Which one is hot, so I can try a bypass to see if the new fan has crapped out?

Of course now, this is no longer a job, ITS A MISSION! 172K mi., probably should bite the bullet and buy another car, but I'm keeping this one until I figure this out...

Also, the old elec. fan ALWAYS came on when the ac was turned on. This one does not, whats that about?

[4.3LXJ]

Sounds like you have a phantom leak to contend with. Better find out where that coolant is going

[Mudderoy]

How's the heat from the heater? You could have a clogged leaky heater core. You could try bypassing it just make sure there isn't a crimp in the bypass hose.

Keep and eye on your overflow bottle.

[Brasscatz]

could very well be the heater core that's leaking... not fun to replace either

[Mudderoy]

http://youtu.be/NDC2Kq5sCOg

[bigjim350]

Yep seems about right, Matt pretty much did all the work. Wanna know the best tool in the world? Its Matt!!!!