I found a leak originating from the thermostat assembly so I replaced it. Since I am sitting at 160k miles I thought it would be a good idea to change the coolant. After draining the old and flushing the system I filled with new. The problem I am having is I am not getting heat from the rear controls but I am in the front. I found 3 bleeder valves to open at different times during the filling process. The coolant exiting the bleeder valve nearest the battery is hot but the one closest to the overflow tank is cold. Do instructions exist on how to properly replace the coolant and if so could someone please share this with me? I am getting a check engine light illumination and it gives me a code of P0126, Insufficient Coolant Temp For Stable Operation. This has me a little concerned. Thanks in advance!
2015 LR4 Coolant Change Issues
- Thread starter JAMike
- Start date
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Likely an air bubble. Turn the heat up on all controls to max (front and rear) and let vehicle warm up. Play with bleeders if air near them. If you are not original owner then coolant change was probably not required because you are likely on water pump #2 or #3 by now.
I have tried setting the controls of the front and rear to hot with the fans on high until the engine reached normal engine temperature. While the engine was running i opened the bleeder valves at different times until no more bubbles bled through. I also ran the rpms at 2500 for short periods of time with the reservoir bleeder valve open. I’ve also turned the engine on and off numerous times to allow it to burp. I have placed enough new coolant in the system to hit the amount one would anticipate is needed for a change. The engine has also been allowed to cool several times over. I am still scratching my head.
jlglr4
Full Access Member
There are actually four bleeder valves: one on the expansion tank, one on the crossover pipe (top front of motor), one on passenger side closer to the back of the engine, and one on a tube coming off the top of the radiator on the drivers side near the expansion tank.
Since you replaced the t-stat, make sure that temp sensor is reconnected properly. If it’s not moving on the dash, there’s something going on with the temp sensor that needs to be addressed.
As for the bleed procedure, I’ve only done it once. Several people swear by the vacuum filler method, but I didn’t have a vacuum filler - but that might help solve your problem. The method I used is below (had my son help me). In the steps of the procedure when the engine is running, it’s essential to keep an eye on the engine temp - shut it down if you start overheating and let it cool off - and make sure the coolant tank doesn’t go empty (you’ll get air back into the system). Since you’ve already refilled the system at least partly, maybe you don’t need to do this whole procedure, but I’ll list it out anyway.
1. Loosen expansion tank and put something underneath it (or wedge it) to keep it raised about 1.5 inches from it’s original position. You just need the lip to be higher than the highest bleed point. Doesn’t take too much.
2. Loosen three bleed points - on the expansion tank, on the crossover, and back of the engine towards the firewall.
3. Fill the expansion tank to the rim and keep filing until it starts to escape the crossover bleeder - close that bleeder.
4. Keep filing until it starts to escape the bleeder towards the firewall - close that bleeder.
5. Close the tank bleeder.
6. Open the fourth bleeder near the radiator, not far from the expansion tank.
7. Start and run the engine and keep adding coolant until coolant starts to run from the radiator bleeder. Close it off.
8. Turn off the engine for a couple minutes. Set the heater on high and start the motor. Hold the engine speed at about 2000 RPM until the coolant level in the tank drops. Have someone ready to add coolant if necessary - need to keep it near the cold fill at least.
9. After the coolant level drops, raise the RPM to 3500 until hot air is emitted from the face vents. Shouldn’t take too long. Keep an eye on coolant expansion tank and keep level in the cold fill range.
10. Put back the expansion tank.
11. Keep topping off the coolant level after driving until it becomes stable.
Since you replaced the t-stat, make sure that temp sensor is reconnected properly. If it’s not moving on the dash, there’s something going on with the temp sensor that needs to be addressed.
As for the bleed procedure, I’ve only done it once. Several people swear by the vacuum filler method, but I didn’t have a vacuum filler - but that might help solve your problem. The method I used is below (had my son help me). In the steps of the procedure when the engine is running, it’s essential to keep an eye on the engine temp - shut it down if you start overheating and let it cool off - and make sure the coolant tank doesn’t go empty (you’ll get air back into the system). Since you’ve already refilled the system at least partly, maybe you don’t need to do this whole procedure, but I’ll list it out anyway.
1. Loosen expansion tank and put something underneath it (or wedge it) to keep it raised about 1.5 inches from it’s original position. You just need the lip to be higher than the highest bleed point. Doesn’t take too much.
2. Loosen three bleed points - on the expansion tank, on the crossover, and back of the engine towards the firewall.
3. Fill the expansion tank to the rim and keep filing until it starts to escape the crossover bleeder - close that bleeder.
4. Keep filing until it starts to escape the bleeder towards the firewall - close that bleeder.
5. Close the tank bleeder.
6. Open the fourth bleeder near the radiator, not far from the expansion tank.
7. Start and run the engine and keep adding coolant until coolant starts to run from the radiator bleeder. Close it off.
8. Turn off the engine for a couple minutes. Set the heater on high and start the motor. Hold the engine speed at about 2000 RPM until the coolant level in the tank drops. Have someone ready to add coolant if necessary - need to keep it near the cold fill at least.
9. After the coolant level drops, raise the RPM to 3500 until hot air is emitted from the face vents. Shouldn’t take too long. Keep an eye on coolant expansion tank and keep level in the cold fill range.
10. Put back the expansion tank.
11. Keep topping off the coolant level after driving until it becomes stable.
jlglr4
Full Access Member
Sorry - I see now that you said the engine is coming up to temp (presumably on the dash display). There are two temp sensors - one at the back of the motor on the heater manifold and one near the t-stat. I believe the dash takes the reading off the rear sensor, but I’m not sure. Just thinking the code could be coming from that front sensor if it’s not connected properly, or maybe there’s an air pocket there.
Thank you jlglr4. I will open that fourth bleeder valve on the radiator I didn't see and elevate the expansion tank.
Ktm525...if you set the front controls to "rear" then the rear controls function otherwise if it is left on "auto" the rear passengers are at my mercy.
Ktm525...if you set the front controls to "rear" then the rear controls function otherwise if it is left on "auto" the rear passengers are at my mercy.
jlglr4
Full Access Member
If you are only opening the forth bleeder (which is a good idea to try first), you probably don’t need to elevate the expansion tank as that forth bleeder is already lower than the expansion tank, and the forth bleeder is opened and closed with the engine running (i.e., coolant circulating). If that doesn’t work for you, I’d let the engine cool, then go through the whole procedure.
Right but when you say no heat do you mean the vent in the third row on the drivers side? Are you getting heat under the drivers/passenger seat for the second row?
