Question about Jeep Cars & Trucks
I have changed thermostat,housing unit, radiator cap, hoses and bypassed my heater core. The fluids are full and my fan is working.
The 1999 and 2000 4.7 had marginal cooling systems. Mainly the fans.
1) are you overheating when in traffic (moving slowly). Look for fan issues - broken plastic covers etc.
2) If you are overheating while moving down the highway. Check the pressure rating of the cap. While you are at it, pressure test whole system.
3) If you have a lot of miles on the 4.7 (150K+) I personally suspect head gasket issues. If you aren't replacing the antifreeze on the recommended schedule, you could have corrosion issues.
BTW, severe overheat on a 4.7 will kill the motor quickly. Keep an eye on that water level. Those aluminum heads are notorious for dropping a valve seat and ruining the whole motor.
Its a good motor, just keep up with the maintenance and use synthetic oils.
Posted on Apr 09, 2015
A possibility is the water pump. This is what circulates the water through the engine and back to the radiator for cooling. Water pumps consist of several vanes attached to a rotating shaft. If a few vanes are broken, you'll get reduced water circulation, causing overheating.
Posted on Apr 08, 2015
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Posted on Jan 02, 2017
It appears we have an Air lock scenario and you will need to perform a system Bleed.
Park the vehicle on level ground, when cold remove coolant filler cap, start engine and leave to idle, turn heater on full and blower to max. When engine reaches operating temperature watch and listen near coolant filler, keep clear as gurgling and hopefully a boil over should occur. Top up with very warm coolant and wait as it may do it again.
Check for heat inside vehicle if warm replace coolant cap but keep an eye on temperature gauge as the ~Air lock may have moved on from heater matrix/core so proceedure needs to be carried out again from COLD.
If persistent boil ups/over attention must made in the cylinder head
or gasket area, or possibly water pump?
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Posted on Feb 05, 2009
SOURCE: engine block does not heat up
Therefore, the fan clutch is bad and should be replaced... I don't remember if I said or thought this in the beginning, or if I just thought you had checked it. Anyhow, change it and you're done!!!
Posted on Feb 09, 2009
Why was radiator replaced?Did it have heat before ? If it was plugged, the heater core may also be plugged. Try flushing it with a water hose in both directions. I dont know why the botton radiator hose would be cold, the radiator should be a uniform temp and the air coming through the radiator should be HOT, when the engine is at operating temp. What condition was the old coolant? if it was rusty, the water pump may have lower flow than normal.
Posted on Nov 19, 2009
If it is fogging your windows, you have a leaking heater core. Dash removal is required to fix it.
Posted on Jan 11, 2011
Testimonial: "great advice,,but I am not losing antifreeze from my cooling system,"
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