MikeW83

I wonder if it has something to do with Lexus opting to use an air to liquid intercooler, vs. the traditional air to air. Maybe they want you to idle for a minute or two before you shut it off to allow the intercooler to cool the turbo and itself sufficiently before you do heat damage? Hopefully someone with the tech knowledge will chime in here.

satlawyer

So just researching on this a little more. Apparently, not all turbos need to be cooled down...A friends VW Golf GTI is equipped with an intelligent turbo cooling system that a) keeps the oil pumping once the ignition is turned off therefore cooling the turbo down or b) is water cooled which essentially does the same thing after you switch the ignition.

Can't vouch for the veracity of the information above, but after skimming through the user manual of a 2014 Golf GTI, there is no mention of a turbo cool down.

Like others, I think the Lexus Dealership would have mentioned the cool down had this been a critical requirement.

Thoughts?

MikeW83

Well, remember this: The NX is the very first mass produced Lex to get a turbo. The last time Toyota had a turbo (internationally at least, not sure of JDM) was on the Supra. So with the NX being a brand spanking new model, they might not have enough data or training on the subject yet. I'm almost certain it's because of the Intercooler now. If it was using air to air like the VW, I don't think the manual would mention it. But because of the liquid cooling, it probably has something to do with that. This was the article I found mentioning it. I'm no engineer, so IDK. I suspect that as the NX gets many more miles and years under its belt, along with the new IS-t, we'll probably be hearing more about it. That's my take on it
http://blogs.youwheel.com/2014/08/25...utput-version/

*We also have a 2012 Tiguan with a 2.0l T, and it too doesn't make any mention of a cool down or warm up period.

jim256

Post #4 has the quote from the manual

coolsaber

Turbo cooling down is an optimum condition that is suggested but not required from the manual quote. If its recommended i dont think its a required maintenance item. I`m pretty sure if this is was required due to design, the Engine Control software would be designed to have a program to allow engine cooling after shutdown, something BMW loves with their turbos.

In the news, BMW V8 n63 (not tus) were found during testing that these engines would reach critical temperatures during operation. To prevent damage the BMW ECUs after shutdown commands the electrical cooling system to cycle coolant to keep cooling happening to prevent damage.

If the 4 Pot in the NX was found to be reaching extreme temperatures during testing you better believe Lexus would program the car to respond similarly as the BMW. But since I have not seen a thread about cooling system remaining on, i think the lexus tune is probably more then efficent to not need this

Glenn6one9

i had a greddy turbo timer, in my MR2, to keep the engine running after "hard runs"(to help cool down). I never did anything during WARM UP. Engine still on original turbo, with 123,000 miles. It's a 1991 MR2 Turbo. I'm sure turbo tech has gotten better, over 25 years. Maybe...

NXNick

This wasn't mentioned by the dealer at all. I always waited a minute or so before driving off, but didn't know about idling before shutdown. Shutting off air, radio, etc. was always normal for me---but that only took 15 seconds or so.

Guess I'll have to really be more aware of the shutdown times, being a new owner. Thanks for the info!!

Mr645

Outdated information.

in the 1980s turbochargers were oil cooled and if run hard and the motor shut off, the heat would burn the oil sitting in the turbo. However today turbo chargers are water cooled and they are designed along with the engine to allow water to flow even after the engine is turned off. Water will still move through the cooling system with the water pump and engine off. Also todays oil, especially synthetics can handle much higher temperatures without burning. Some cars even have exhaust gas temperature sensors that would limit boost if those temps get too hot. Not sure if Toyota/Lexus does this but some cars do.

SteveDeech

You need to read the history of what went into the building of this first ever turbo 4 from Lexus. I really don't think this is an issue you all should worry about. It is rock solid. Even the turbo's are manufactured by Lexus. All parts in this motor is Lexus OEM.

Unless you are beating the hell out of your NX, I would not worry.