Oil Cooler Mixer Valve

Basically a secondary thermostat for the oil cooler, it is built into the lower radiator hose on the LR3. If it fails(or its o-ring seal) it will also allow coolant to flow when it shouldn't be flowing, causing extended warm up times(in the eyes of the PCM, not always actually extended amount of time)

About 95% of the time it is the main thermostat, but every once in a while, the main t-stat seal is fine, and it is the OCMV. I always prompt customers with the possibility, and suggest the t-stat replacement, and inspection, and then replace the OCMV if necessary.

 

OK good to know, this thing gets crazier all the time, gonna do the main one,engine light has not returned, I really think it is just due to the cold cold weather as I sit here watching the snow

 

The cold weather can make it set the fault easier, but ambient temperature is accounted for in the fault judgement.

Do the main one(as mentioned above, double check that you don't have any leaks starting to form from the housing first) and go from there.

 

ok swapped in the new t stat, the old one had the bulged seal like was suspected, is there a trick to bleeding this I cannot get the stat to open, I run the engine and temp gauge reaches just below 3 o clock heat is super hot out of dash and all hoses are hot except those coming from the stat housing


engine fan is cycling like normal too


I opened the bleed but nothing since coolants not flowing there, the overflow cap is off and bottle is almost full up

 

Is this on your 05? Does it have the bleeder T in the small hose coming off the t-stat housing? - The early ones didn't have that bleeder.

I personally use an Air-lift to suck the air out and vacuum fill it, so I don't have much to offer as far as bleeding it any other way, but you should be able to fill the expansion tank, and open that bleeder(or remove the small hose) until coolant starts to escape. The top of the expansion tank is the highest part of the cooling system, but not by much.

Also, make sure you lower the level to correct before capping it off and calling it a day once it's bled. I've seen way too many of these come in with a completely full expansion tank(mostly due to Low Coolant messages being topped off) which is worse for the system than the tank being almost empty.

 

I do have the bleeder. I put the tank cap on ran it and loosened the bleeder till only coolant came out, on mine that bleeder sits way higher then the tank or at least looks that way


the big hose coming from the stat is still not hot, the big hose on the pass side of rad does get hot cold with fan cycle

 

Well new thermostat and housing and this code is back, now it was in 20s last nite when wife left work so i hope it is that , rover runs at proper temp

 

2008 LR3 4.4L V8. I'm fighting with the P0128 code. I replaced just the t-stat, but the code returned. I then replaced the t-stat with the outer housing (not the whole assembly), thinking it might not be seating well, but that didn't fix it. Replaced the lower radiator hose, based on the thread above that mentions the OCMV...but when I inspected the old hose assembly that goes to the oil cooler, there were no valves in there, just an open flow to and fromm the cooler. That didn't fix the problem. Today I replaced the Coolant Temperature Sensor, cleared the code and still have a pending P0128. Using iLAND, the live stream data from the ECU shows that the temp does not go above 80deg C and the Factory Service Manual shows the T-stat isn't even supposed to start opening until 88d C.

Any thoughts?

 

I know this post is old (and I didn't get any replies), but for anyone trying to tackle the problem: save yourself the headache and just buy the entire t-stat assembly to begin with. My problem was fluid flowing around the thermostat because the housing itself was deteriorated inside. Truck came up to temperature and no issues after replacing the entire assembly.

 

I'm having similar issue. on my 2011 Range rover HSE P0128 keeps coming back. Thermostat has been replaced 3 times. This time I drove more then 300 miles before it came back.
Today when I scanned It had P0128 and B1D27-15 (intermittent) codes.
I don't know what to do.
Does anyone know what could be the issue?