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horse86



Member Since: 09 Dec 2014
Location: PA
Posts: 860

United States 2014 Range Rover Autobiography 5.0 SC V8 Causeway Grey
P0128 Thermostat replacement how-to? 2008 4.4L

2008 Jag Engine 4.4L.

So I'm getting this p0128 code. CEL is on. Temp needle stays in the middle when engine is warm like normal so I'm guessing its the thermostat that needs replaced.

Is there a how-to with pics or video? I can only find videos online of the Sport or LR3 etc.

Is this an easy DIY job that can be swapped at home by simply clamping off the hose? Or is this a dealer repair where they need to re-pressurize the system etc.? 2014 FF Autobiography 5.0 SC
2008 FFRR (sold)
2008 BMW M5

Post #534303 15th Nov 2019 2:28am
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maric995



Member Since: 04 Apr 2019
Location: zagreb
Posts: 58

Croatia 2006 Range Rover HSE 4.4 V8 Zambezi Silver

Hi,
You can look in this video for supercharged rr sport. The position of the thermostat is the same as in 4.4 so you can follow this video. You only have to remove top plastic engine cover. I would drain the sistem with the drain pipe on the left bottom end on the radiator. For the filling of the coolant: top up the sistem slowly with a bleeder cap open (plastic screw on coolant tank). You will have to wait a little bit as the air comes out, the fill level will drop few times. After this, start up the engine, allow it to heat up to the operating temperature slowly without driving(don't rev it). Turn off, wait for it to cool down and top up the coolant again. That's it, don't forget to use pink coolant (I used pink shell coolant)

Filip

Post #534307 15th Nov 2019 7:12am
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horse86



Member Since: 09 Dec 2014
Location: PA
Posts: 860

United States 2014 Range Rover Autobiography 5.0 SC V8 Causeway Grey

Awesome! thank you for the input

Thats the vid I saw but didn't think it related as it was a sport

So update this morning: Drove about 15 mins (5 miles) to work and the temp needle never made it to halfway (12 o' clock)....it only made it a little past 1/3 on the gauge I would say. I'm on the right track that this would point to bad thermostat? I thought I recalled seeing there are 2 thermostats on this 4.4 v8 Jag engine (top - like the video, and a bottom by the radiator?)


Would this also effect some rough transmission shifting? I though I read that this also cools the tranny fluid?


Looked on FCP EURO and found the thermostat LR005765 and the Land Rover Engine Coolant Thermostat Assembly LR007604....Do I need to do the whole assembly or just the thermostat?


Do I need to drain the whole system? I had my rad replaced a year or so ago so I don't want to waste all that new-ish fluid...can I just clamp the hose like the guy in video?

I also have the pink/orange fluid....do you know what the Shell Pink stuff is called? Can mix that with the pink OEM coolant? 2014 FF Autobiography 5.0 SC
2008 FFRR (sold)
2008 BMW M5

Post #534363 15th Nov 2019 12:56pm
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maric995



Member Since: 04 Apr 2019
Location: zagreb
Posts: 58

Croatia 2006 Range Rover HSE 4.4 V8 Zambezi Silver

I am 99% sure that the simptoms you described are linked to the coolant thermostat. You do not need to buy the whole assembly, just the thermostat with ''o'' rings. After that clear the engine codes and go for a test drive.
As I didn't had the clamps, I drained the whole sistem, but if you have clamps you can use them like in this video above.
I used Shell premium antifreeze longlife (pink colour), and I think that this coolant has land rover approval, but I didn't look at that too much. You can mix it with oem coolant as this antifreeze is made for all aluminium engines like 4.2 is.

For the rough tranny shifting I don't know if you can blame the faulty thermostat, but it could possibly be linked as the tranny oil heats and cools with engine coolant via special radiator next to the engine radiator. You certainly need to change the top thermostat and see if the things will go for the better. Smile

Filip

Post #534655 18th Nov 2019 6:54am
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