I purchased this lr3 from my sister. While she had it, she was having overheating issues. I worked on her car before I bought it. I changed the thermostat, the expansion tank, and all of the coolant system hoses. The car was still overheating, but it turned out the system just needed to be bled. The car started overheating again and water was coming in due to a clogged sunroof drain, so I bought it from my sister.

I noticed the oil adapter housing was loose, and it looked like there was a leak comin from it. I tightened the oil adapter housing to the block. I drained the system and removed the thermostat and filled the expansion tank with water, but the system was still overheating.

The procedure I used:

Parked truck front facing up hill
Opened the bleed screw on the expansion tank
Opened the expansion tank cap
Filled with distilled water to the max cold fill line until the truck stopped taking it
I closed the bleed screw
Closed the expansion tank cap
I started the truck and let it get up to temp
I turned off the engine
I opened the expansion tank cap and let the air out
I filled the tank 30mm past the max cold fill line
I put the cap back on and let the engine cool down

I started the truck and let it get back up to temp. Before I could take it for a test drive, the lower radiator hose blew off. I thought I might not have tightened it right, so I re-fastened it and paid better attention. I repeated the bleed process. The truck started to overheat shortly after it got up to temp. I shut the engine off immediately. I opened the expansion cap and the upper radiator hose started knocking almost like an air hammer was going through the line. I could see it physically moving. I was getting a low coolant message on the dash although the coolant level was past the max fill line. I had the heater on to the max, but it was blowing cold air. The return hose from the heater core was not hot like the rest of the coolant hoses and the lower radiator hose going to the thermostat looked to be inflated. What could be causing the overheating issue? Am I just not bleeding this properly? Water pump? Clog in the system?

 

Did you check the oil level? Lack of oil can cause overheating. And if the oil adapter was lose, then there would be no oil. It is under incredible pressure right there and would have easily escaped.

As for bleeding, do not park up hill. Bad idea as air could be trapped at top of radiator. Should be on level ground with bleeding preformed from the bleeder-t-fitting on top and the bleeder screw at the expansion tank.

Also it could be a blown head gasket if the cooling system appears to be under great pressure.

 

I moved the vehicle into my garage (flat ground). The oil level was a quart low, so I topped it off. Although the bolts where loose on the oil filter adapter housing, doesn't look like any oil leaked out. It was coolant puddling under the oil filter adapter.

I retried the bleed process using the bleed screw on the expansion tank and the t bleeder at the top of the system. Am I supposed to bleed with the expansion tank cap on?

I was finally able to get the car to maintain temp so I took it for a test drive. Coming up the hill, in the division up the street, we started to overheat. I shut off the engine and opened the hood. The t bleeder valve was spewing steam. I took my sock off and used it to tighten it, but I could still hear pressure escaping. I opened up the expansion tank to relieve pressure and add more water. We sat around for a few and waited for the engine to cool. I started her up and drove up the block to park her in my drive way.

During the bleeding process I heard what sounded like a faint horn blowing. Is this what a water pump sounds like when it's done for? I'm thinking my next test should be combustion gasses in the coolant system. Seems like that problem would trump all. Thoughts?

 

The pump usually leaks, but noise is always possible. The pump is very easy to replace. You can do the initial bleed with the cap off but not driving/reving the engine. I often over-fill and then squeeze all the hoses I can access to help push coolant around. Keep in mind you can also use a shop van to pull air and coolant through the system. Ultimately you should see coolant entering the expansion tank at the very top near the bleeder screw - that coolant comes from a small hose. It should be getting pulling into a small compartment at the top of the tank when the engine is running. If not, you for sure have incomplete coolant flow.

 

Going to add something I forget about.... you said you replaced the expansion tank, OEM? If not you want to check the cap. Seller's interchange the LR3 and LR4 tanks w/caps. And even the caps themselves. The 4.4 V8 is only 16psi rated. If you have an LR4 cap, the system will over pressurize well before the cap relieves pressure. Should read 110kPa not more than that.