Over heated the comanche in traffic today. Had to push her hard to get her off the road and to my buddy's house a few blocks from main road. She boiled all her water out in traffic to the point the heat was blowing cool air with ac off. What should I check? After letting her cool and filling her back up she ran like she was running out of gas for quarter of the mile to my house, then she ran fine the rest of the mile. Checked the oil and it still looks like new with roughly 1,000 miles on it and 1,100 miles since replacing the head, head gasket, water pump, thermostat and with fresh 50/50 antifreeze and water. Please help she's my daily driver since my cherokee is also suffering from leaky rad and plugged cat.

 

Stop and go or slow traffic main suspect fan clutch.

 

Even though you've said your replaced a lot of the cooling system, you should look it over again and make sure nothing is bad (like the t-stat or pump) A bad clutch fan will cause overheating at idle, as will a bad electric fan (if the MJs have those, idk.)

Did you have the head checked for cracks when you had it off?

 

PO cracked its original head. I bought the mj with a good used head in the passenger seat. Truck sat for 5 years with no head. I cleaned it up and got it running. Ran fine for 3 months. This is the first major problem I had with it. I always use the ac so the electric fan is always on. My pressure bottle never holds pressure. She usually runs below 210.

 

Still the Renix cooling system with the pressurized bottle? If so, hightail it down to Napa and get a 703-1396 cap for the bottle.

 

Also has a 195 t stat. I do add antifreeze now and then due to leaky pressure bottle. Here's a photo of what she usually runs temp wise. She usually hits 210 while sitting in traffic but cools down as soon I speed up a bit. I'm just worried about it cracking another head as the block has over heating problems in the past

 

Deff gotta hold pressure.Hows clutch fan when at operating temp ?

 

I have replaced the cap when I first got her running. Same thing I did to my 89 xj when I replaced the pressure bottle.

 

Get a bottle if it's leaking in a place other than the cap. If the cap, get the cap I posted about. If the bottle, get the bottle and the cap I posted about. Kapeesh?

 

Seems to move plenty of air. Still has the factory shroud. I keep my ac condenser clean of bugs and mud to promote air flow. Both fans seem to be moving good amounts of air. I can feel good draw of air from the grill.

 

When at operating temp shut off motor and give it a spin with your hand see how far it turns .

 

Replace bottle, got it! Anything else should I do as preventive maintenance? I'm gonna be traveling throughout the summer with the truck and I don't want it to overheat again.

 

I will give that a try.

 

Wanna end all this upgrade to open system and never look back.

 

What I am currently in the process of doing in my 89 xj with the closed system. When at operating temp the fan clutch has little resistance to spin but stops quickly when I let go. Is that possible bad fan clutch?