I have a 98 zj with a 5.9l 165k and it constantly overheats.
Info on Jeep:
I have replaced the plenum pan gasket, intake gasket(which were horrible), thermostat, burped cooling system for hours on end with numerous gallons of coolant, E-fan is direct wired on high at all times.
No matter what the temp is outside, no matter what manner I drive (highway, off-road, city), the jeep overheats, heat stops being hot and the overflow bottle boils!!!
I have tried everything to burp the cooling system and I always have the same outcome steam and boiling the overflow bottle.
What temps are you getting on the guage?
Are you running a proper coolant mix or just water?
For coolant to actually boil in the expansion tank it's got to be really hot (I don't recall the temp). Plain water will boil in the expansion tank at normal operating temps.
Had a '97 that did the exact same thing. Ended up being a cracked head. Replaced them both with new ones and problem solved.
"Si Vis Pacem Para Bellum"
"Great danger lies in the notion that we can reason with evil"
...We use words like honor, code, loyalty. We use these words as the backbone of a life spent defending something. ...I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the blanket of the very freedom that I provide, then questions the manner in which I provide it. I would rather you just said thank you, and went on your way, Otherwise, I suggest you pick up a weapon, and stand a post...
I bought the HI-WAY BLASTER HORN that's 139dB and every time I honk the horn an Angel dies.
16 - He causes all, both small and great, rich and poor, free and slave, to receive a mark on their right hand or on their foreheads,
17 - and that no one may buy or sell except one who has the mark or the name of the beast, or the number of his name.
18 - Here is wisdom. Let him who has understanding calculate the number of the beast, for it is the number of a man: (Real ID and RFID chips)
Think about it...
1. Scan for codes
2. Do a compression check with all plugs out, throttle held open with screwdriver and fuel pump relay and coil wire disconnected. Post results.
3. Is there ANY oil in your coolant recovery bottle? If so, watch for little bubbles bubbling into bottle from overflow tube. =head gasket.
4. If you have a low cylinder do a leak-down test or go to NAPA and get what they call a block tester to confirm head gasket. It samples the gas in the radiator and indicates exhaust leak into coolant.
5. Have you blown any hoses?
Fix your fan, it helps nothing running on high full time. If you are in a cold environment it can cause problems.
Sounds like you have more than 1 issue going on. The scan for codes and compression check should sort it out. Compression check and leak down kit at Harbor Freight for about 35 bucks each. Block test at NAPA FOR 40+-.
I just fixed my overheating problem I had for a week. I was driving with the temperature gauge passing the third quarter (engine smoking). I know you've done this already, but I ended up leaving the rad cap and bleeder open for about 15 minutes running. It blew out sooooo much air and bubbles while filling the rad. Engine stayed cool ever after.
Does the temperature drop while the heater is blowing?
burped cooling system for hours on end with numerous gallons of coolant
I've only used 2 gallons give er take a little . Where's your coolant going ? Makes it look like a head/gasket issue . I agree with Snowfan . Could be a cracked head also . If compression tests show an issue , and you do end up taking it apart , be sure to have the heads checked for cracks . It would be a lot of wasted time to do a gasket job twice .
Only thing that confuses me here is no mention of white smoke or coolant smelling exhaust Problem seems bad enough , these symptoms should appear . No mention of leaks on the floor , or anywhere on the engine so the typical by-pass(maybe replaced during plenum job) should be fine . Another typical leak is the timing-cover gasket . It would have to be blown completely to the point a leak would be obvious . I have one leaking for 3 yrs and still no issues other than a top up every 6 months or so . If you don't ave a puddle from it , I don't see it being an issue .