Bdub215

iTrader: (1)

The MAF sensor isn't located anywhere near the throttle body. PS hypervish **** off. Sent from my iPhone using Tapatalk

BDSL

There is absolutely no way your intake air can get that hot.
As I said, ambient air is 80degF. It can't climb to 170F between the air intake and the air filter...
If that is truly case, your air filter (which is made of paper) will catch on fire....

Hayk

iTrader: (1)

Heat shouldn't be an issue. Sludge is usually formed from not burning off moisture, not getting to operating temperature, and letting highly contaminated oil stay in the system for too long.

p.s.: Correct me if I'm wrong, but a MAF sensor is designed to measure volume not temperature. It doesn't have a temp sensor inside.

Power6

MAFs will often have a air temp sensor incorporated in them. Just a packaging thing, it could easily be elsewhere. 170 intake air does seem a bit wrong...you'd need one heckuva heat exchanger to put that much heat INTO the intake air.

I have not heard of a link between heat and sludge, turbo motors are not known for sludge and most certainly put more heat in the oil via turbo bearings and have way more underhood heat than any N/A motor.

Bdub215

iTrader: (1)

That's half true. If you don't follow the proper cool down procedures for a turbo motor, the turbo oil lines will start to sludge up. And it can spread to the motor if it's bad enough. Usually takes out the turbo before it does. And there's no fancy heat exchanger, it's general engine heat when the car is at idle. Soon as the car moves, that number drops fast.

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BDSL

I have a turbo vehicle and I can tell you sludge can be an issue for the following causes:
- wrong oil
- insufficient cool down period
- improper gaskets / sealants used around that area
- improper fasteners used around the coolant / oil lines causing leaks
- etc...

It is not sludge in the line. It is the bearing inside the turbocharger that is being seized up. Turbocharger can reach extremely high temperature.....+1000degF. Oil flash point is around 400degF. If the driver turns off the engine after a hard run, the oil will vaporize inside the turbocharger. Once the turbocharger is seized, the engine will run crappy. Sludge does NOT spread.

BDSL

I believe some MAF (mass air flow) does NOT have temperature sensors in them. A lot of people converted to MAP has to install intake air temperature sensor.

BDSL

If you have a proper cooling system (i.e. Thermostat, radiator, fan, line, etc), the temperature of the coolant should be maintained around 180degF. Intake air will not get to 180degF....until it reaches the pistons.

Hayk

iTrader: (1)

From my basic knowledge of turbo motors, the whole cooldown time is nonsense. I guess you could run the risk of damaging components if you're racing the car, but average aggressive driving shouldn't be a problem.. I believe all modern turbo cars come with preventative oil drains and active cool down measures to battle overheating of turbos. IIRC, there is a coolant and/or oil passage that circulates the turbo to control its temperature after shut off.

BDSL

There is a warning sticker on the visor and also in the owner's manual about this.
Depending on the turbocharger, some only have oil passage (no coolant).
Either way, one shouldn't shut down the engine right after hard acceleration or highway driving (under high load). One side of the turbo is contacted to the exhaust which gets really hot. If you see some videos on youtube, you can see the exhaust manifold (if there is not heat shield) glowing red hot...even when you pull over from the highway.

When the driver shuts down the engine, the flow of oil and coolant stops. Whatever is around the turbocharger will be subjected to the extreme heat. By idling 1-2 mins after high loading, it allows both oil and coolant to bring the turbocharger temperature down to the acceptable temperature.

There is aftermarket turbo timer that keeps the engine running for a period of time after the ignition has been turned off. But that will require the driver to leave the gear in neutral and the turbo timer might not work with the factory alarm....

artbuc

The Denso MAF sensors in my RX300 and Avalon and other 1MZFE V6 engines I have worked on have a built in temperature sensor which gives the IAT reading on a scanner.

Hayk

iTrader: (1)

That's what I meant. There are systems in place, at least in modern turbo cars, that keep the flow of oil and/or coolant, even after the engine shuts down. That's why those aftermarket turbo timers are a gimmick. MightyCarMods did a bit on this not too long ago.

There are a lot of modern turbo cars out there, and I bet 95% of their owners do not know anything about this issue. If things were really this serious, car companies would be out of money due to premature engine damage and countless warranty claims.

BDSL

But these types of turbo failure is caused by owner's negligence. All the procedures are written in the owner's manual. Its like people applying brake while going downhill for a prolong period of time...such brake failure would not be covered by warranty.

ALex4Life

I would definitely change the belts (timing and serpentine) because it's not just the mileage to worry about but it is also the age of the car. While they are in there I would have the water pump replaced along with the front seals if necessary.

As far as oil changes, 3,000-5,000 miles is sufficient. I used to change mine at 3,000 until a Lexus specialist told me I was wasting my money and these cars could do 5,000-7,500 easily on a good quality oil. I use full synthetic by the way (Pennzoil or Mobil 1). Also, not sure If you mentioned where your getting your work done at, but I would avoid the Lexus Dealer unless you absolutely have to.

Toyota dealers are capable of performing any maintenance on these cars. I had my belts, water pump, and front seals and few other things replaced at 88K for about $800 at a Toyota dealer.

Power6

This seems to be the case. But old habits die hard, this stuff wasn't always true so the idea of the turbo timer lives on from the 80s. Even then I had a Buck Grand National, it had no coolant jacket in the turbo. My version of a "turbo timer" was not to drive like a nut the last couple miles, which worked fine. Nothing like fresh air over the oil cooler to bring the temps down. I have had an oil temp gauge in this car and my WRX and you can clearly see hard driving stresses the oil temp and easy driving brings it back to normal.

I found my sisters 1.8T Beetle has an electric coolant pump that keeps the coolant moving after shut down, and the Subaru turbo motors have an ingenious high mounted coolant tank that causes a siphon flow when the motor is shutdown, as coolant vaoprizes in the turbo jacket it rises and pulls more coolant into the turbo. If you listen close you can hear the bubbling after you shut down.

I think some of you peeps are just making stuff up with this turbo sludge, the term for overheated oil flashing off and solidifying is "coking" which is what can happen to the hot oil in side the bearing exposed to intense exhaust gas heat (which can reach 1500deg for you turbo peeps who used to tune by EGT), not the same thing as sludge, it is much worse. The flash point of synthetic oil is higher than organic, so this is why we want to use synthetic oil in a turbo motor. My knowledge of slude is less so, but I did not understand it to be a heat issue. It was solved by making oil return passages bigger nothing to do with heat.