Rx 400 thermostat change

[JSeaman]

Has anyone changed the stat on an rx400 and if so did you need to remove all the hybrid system?

[ColinBarber]

It's a major pain. Wipers and motor all out to remove the top cowling, drain engine and hybrid coolant, disconnect/remove the power steering ECU, remove air box/filter - and yes the hybrid inverter needs to be removed.

I think you want to be sure the thermostat is faulty before doing this, not just replace it on a whim. 

[JSeaman]

Wow that sucks, I have the fans kicking in, no heat in the cabin, one cold hose and one hot one so I figure it's the stat

Is there a decent service manual around anywhere do you know?

 

[Herbie]

Just PM'd you with some info that may help James.

[JSeaman]

That is hugely helpful, thank you so much for that! I'll give it a try and see how I fair, many thanks

[welland]

12 hours ago, JSeaman said:

Has anyone changed the stat on an rx400 and if so did you need to remove all the hybrid system?

Is there a single thermostat, or two: one for each coolant circuit?

[ColinBarber]

16 minutes ago, welland said:

Is there a single thermostat, or two: one for each coolant circuit?

Single. The hybrid cooling system has a separate pump and uses a separate core within the same radiator assembly but there is no need for a thermostat to regulate an optimum temperature as with the internal combustion engine - the colder the better to keep the electronics and motors cool. 

[JSeaman]

Well, the stat is changed - not too bad a job after all, only took an hour to strip it all down.

I tested the stat and it opened but slowly and slightly so wanted replacing but wasn't enough to cause the symptoms. Moved over to the other side of the engine and the water pump is weeping so that's now being done along with the timing belt. Thanks again to Herbie for making this a lot easier than it would have been!

[Herbie]

You're welcome James, glad I could help.

[JSeaman]

Well, things were going well but hit a bit of an obstacle. The timing belt and and the water pump are done but it says Check Hybrid System and Check VSC System when I try and start it. I've put a charger on the 12V cell in the engine bay but it's reading 12.3V so don't think it's too low

[Brandipity]

On 8/31/2020 at 9:17 AM, Herbie said:

Just PM'd you with some info that may help James.

Hi Herbie, the thermostat on my wife’s 06 400H has decided to stick open, and I’m looking to replace it. Would you mind relaying this info to me as well? Thing looks like an absolute nightmare to replace.

[Herbie]

8 hours ago, Brandipity said:

Hi Herbie, the thermostat on my wife’s 06 400H has decided to stick open, and I’m looking to replace it. Would you mind relaying this info to me as well? Thing looks like an absolute nightmare to replace.

Hi Brandon,

Just sent you a PM which will hopefully help.

[Burtwyn]

Hi all, 

 I know this is an old post, but my mechanic thinks my thermostat has failed too. I've had a cracked radiator and the car is still overheating after replacement. The bottom radiator pipe is remaining cold leading him to think the thermostat has gone. @Herbie would you be able to share the details on replacement with me too please. TIA :-)

[Herbie]

2 hours ago, Burtwyn said:

Hi all, 

 I know this is an old post, but my mechanic thinks my thermostat has failed too. I've had a cracked radiator and the car is still overheating after replacement. The bottom radiator pipe is remaining cold leading him to think the thermostat has gone. @Herbie would you be able to share the details on replacement with me too please. TIA 🙂

Just sent you a PM now Roger, hope it helps.

[htyler]

Hi Herbie. I know this is an old topic but I'm researching best method to replace the thermostat in my RX400H. Local garages do not want to touch it. Could you send me the info you have shared with others please. Many thanks