2015 North American LR4
3.0 V6 supercharged

I just replaced the radiator and I think I'm having issues bleeding the system.

I poured new coolant both ways in the upper pipe toward the engine and to fill up the radiator. Same with the supercharger radiator, this got the back of the engine bleeder valve to have coolant come out.

The temps are not coming down after short test drives, I shut it down once it hits 225-230.

I am using the GAP tool reading both temp sensors. One is raising just like the instrument cluster but the other sensor is stuck in the 80's fahrenheit. Hoping this could be a clue to how to resolve the issue.

 

I've done tons of cooling system work on mine (hoses, pipes, pumps, radiator, etc) and except for one time, I've never been able to successfully bled air out without using a vaccum lift to suck all air out. Plus it's way faster to fill and be done this way.

 

The car can be manually bled, but there is a pretty specific procedure that needs to be followed. Not enough to just pour in coolant until it’s coming out the bleeds. See here, post #12, for the procedure: https://www.landroverworld.org/threa...-2#post-240252.

 

Thanks, will try today

 

Also, my understanding is that the two temp sensors should be different. One is measuring the temp of the coolant coming out of the radiator (cool side), and the other is measuring the temp of the coolant coming out of the block. A differential of 80 to 225 seems a bit much, but I don’t remember anymore what the differential looked like on mine. When you first start the car after leaving it overnight, that lower temp sensor should be right around ambient air temp. It will basically stay there until the engine gets warm enough for the t-stat to open, then the closed coolant passage through the block will be opened up and coolant will start flowing through the radiator and back into the block. At that point the coolant temp coming out of the radiator will rise (the radiator only takes some of the heat out, but doesn’t get it all the way to ambient temp - but there will still be a significant difference in temp.

 

Thanks, I did reach out to Gap IID tool tech support. They don't have a way to know which temp sensor is which when you select temp sensor 1 and temp sensor 2. Their software just sees two sensors and they relay the readings from each.

In the workshop manual temp sensor 1 is in the rear of the engine and temp sensor 2 is on the hose just below the thermostat.

 

Finally got it figured out. Bad thermostat. Was not opening.

I did unplug the front thermostat to diagnose which temp sensor was which when viewing them with the Gap tool.

Temp sensor is the rear temp sensor that is on the rear heater manifold.

Temp sensor 2 is just below the thermostat housing.

This is the same description as the temp sensor 1 and temp sensor 2 in the workshop manual.

By watching both temp sensors you can tell when the thermostat opens up and the sensors begin reading similar temps.

I was able to bleed the system manually. The most important thing need is patience. Many times of starting the engine, running the heater and then letting it cool down and adding more coolant and using the bleed screws. The big thing to wait for is the engine running with the heater on and listen to the coolant make the water fall sound in the heater core shortly after the low coolant warning is displayed. Shut off the engine, let it cool down and add coolant. Still a couple of time after this to add small amounts of coolant after letting it cool down from short test drives.

I would highly recommend watching the temps with a device that plugs into the ODB II port when bleeding. I also have a Blue Driver and it only reads one temp sensor. It is sensor 1 at the rear of the engine.

Per the workshop manual if the ECU does not get a reading that makes sense from the temp sensors it will give a reading on the instrument cluster based on what it thinks the temps should be on the time the engine has been running. When this happens I was getting no temp adjustments with either sensor but the instrument cluster was giving a reading. Turn off the engine and turn it back on and the instrument cluster goes back to cold. With some revs the water finally got flowing to the temp sensors.

 

The manifold ECT on mine's reading steady between 190F-210 F today, depending on whether moving or stationary.

The t-stat temp is reading between 120 F and 165F, varying wildly constantly but not in relation to heater manifold temp.

Does this mean anything?

I've never monitored t-stat temp so I've no reference but I've been trying to chase down a pressure issue and a fauty t-stat's been suggested. They've been on global backorder for the past couple of months, where did you source yours?

 

Your thermostat may be not opening fully if temp sensor 2 it is topping out at 165.

Due to the back order, I elected to put in the thermostat housing from the V8 LR4. This has the same hose connections but has a normal style thermostat (not electric) inside to control the bi-pass and open the thermostat. The thermostat housing for the V6 supercharged 3.0 has an electronic thermostat. Per the workshop manual this is so the ECU can manipulate the bi-pass and thermostat flows without having to wait for the water to heat up to "control the flow and pressure, to protect the engine components." The bi-pass starts fully open on the V8 thermostat housing so the flow is there and the thermostat is 190 degrees when it begins to open vs. "208-2015" to begin to open and "226" fully open.

I took the old electrical connector off the old thermostat housing and made a blank out of it and wrapped it with gorilla tape and then zip tied it secure. No codes, I think it was just an electrical current with no feedback to the ECU.

I like having a lower temp thermostat. I'm coming from the D2 world where Land Rover intentionally ran the engines hotter to comply with emission standards. The negative part is hotter engines over time don't last as long. I believe the same is being done with a lot of newer engines, hotter for emission requirements at the detriment of the life of the engine. Running in in the 190's.

 

I don’t believe this wild fluctuation should be happening. Sounds like either a bad temp sensor, air in the radiator making its way to the temp sensor, or a wiring problem with the temp sensor.

However, the temp sensor near the T-stat does not control the t-stat (to my understanding). This is the cold side t-stat that monitors the temp of the coolant coming out of the radiator before it joins the loop through the block. This t-stat should always be significantly cooler than the hot side t-stat, which is at the back of the engine measuring the temp of the coolant leaving the block.