so yesterday I noticed my 06 LR3 with the 4.4 V8 was low on power when accelerating from a stop light. Looked at my temperature gauge and it was pegged at the max. I pulled over and checked it out. No steam, no coolant anywhere, everything looked good. Turned the truck back on and the gauge went back to
the middle. Worried about overheating, I drove home with a watchful eye on the temp gauge. It went back up but as soon as I got in my driveway, I heard a click under the dash and the gauge went back to the middle. Open the hood and there's steam and coolant everywhere. The T-Connector bleed screw broke. So I buy a brass union and reconnect the pipe. Turn the truck on and turn the heat on to circulate the coolant and nothing happens. No heat at all. So I replaced the thermostat today and start the truck again. Gets up to temp just fine, but still no heat. The heat was working this winter by the way. So I open the bleeder valve om
the expansion tank thinking maybe trapped air may be the culprit and after the air comes out, so does coolant which makes me think the water pump is working fine.

so summary:

overheating > yes coolant > t connector broken > replaced t-connector with brass union > no heat > replaced thermostat > yes still coolant > still no heat > bled the system of air > still no heat > coolant is now boiling.

What do I do!?

 

I had the same issue with the t connector and no heat. Mine was a pain to bleed as all are apparently. Bleed it again, it takes a bit of time, then drive it. My heat would not come on sitting in the driveway. Once I drove it a few miles it began working again just fine.

 

If you have a local shop that has a vacuum bleeder, you could get them to evacuate your coolant, observe the vacuum for a few minutes to make sure there are no leaks and then refill the system with either your old coolant if it's still good or use the opportunity to get new coolant in your system. This is about the only way to ensure you don't introduce air into the system which can be near impossible to get out.

 

+1 on the vacuum bleeder. Been using one for almost 10 years now, makes me wonder how we fixed cars without it.

 

Easy.

Look up my old posts. Do NOT use the stupid bleeder T thing.

Leave expansion tank cap off
Warm up motor, couple mins @ 3000rpm
Heater on
moment thermostat opens shut motor down as the loop opens
top up expansion tank as it drains into the loop

repeat as necessary. Simple.