MJHSC400

I did search this topic on several forums, and then on a few other forums, then google...

I am posting it again for discussion purposes hoping to get answers and maybe others will gain some knowledge from it too.....

My 92 SC400 has the white cloud burnoff at startup---

Some say that the power steering ACV, air control valve can go bad and allow the vaccum hose to the manifold to ingest p/s fluid and burn a white cloud off..

What I am wondering is if the SC400 has the same p/s system as the LS400 and the same inherent problem..

Also if there is a workaround or quick fix, or just a really good way to determine the problem--

I just don't want to accept that the valve guides or seals are leaking on a 1 owner dealer maintained car even with 153k miles-- since Lexus spent nearly half a billion dollars designing this great engine...

I have not done a compression test yet, but it's in the plans...

I am just hoping to find that it is the power steering fluid burning problem before I ever do a leakdown test and fix the problem and curb the smoking on startup..

My biggest headache is that when I went to test drive the car, he started it up and it didn't smoke 1 penny, and the exhaust smelled clean and properly burned.....

To get it home all the way from Dallas and find it doing this on startup is frustrating to say the least, especially since I still need to replace the engine mounts and rebuild the entire front suspension, do struts, and do some rear bushings as well..... This car is racking up a long list of expensive work to do..

The white smoke does have a distinct smell, but I havent' smelled enough exhaust to determine if it's coolant or what-- it smells sweet though for sure, but also alot like a rich fuel mixture.... I guess from open loop cold startup...

MJHSC400

hmmmmm

5spdSC300

iTrader: (1)

For starters, there is no way the engine can suck in any power steering fluid from a broken power steering ACV. It does sound like you have leaky valve steam seals which is a common problem for higher milage toyota engines. Do you get a puff of white smoke on cold starts? Does it usally happen when the car has been sitting a for a period of time, like over night, then started? Time allows the oil slowly seep through the leaky seals and during start up, it burns all the oil which is what caused the puff of smoke on start up.

MJHSC400

This Thread notes a similar problem.....

That is why I am inquiring other SC owners to find out if the power steering system is the same or similar to that of an LS400 first gen...

5spdSC300

iTrader: (1)

It never crossed my mind that PS fluid could go through the ACV when they decide to take a crap. My experience with ACV's when they fail are the nipples on top for the vaccum lines like to break off probably due to age since they are plasic.

My question is if PS fluid is being sucked into the engine through the ACV, wouldn't there be ps fluid constantlly being burned which would cause the car to be smoking all the time and not just sometimes? Depending on how bad the leak is through the ACV, your ps fluid would be low after sometime of this happening. Have you checked you ps fluid level?

Your symptoms still sound like valve steam seals and at 150k miles, they are due if they have never been changed. When exactly does the car smoke, how much, and how often? Also take note if it's mainly happening on cold starts.

MJHSC400

according to the thread, the smoke only lasts a few seconds-- and mine is the same--

How much would valve seals on a 1UZ run for parts/labor?? Just wondering in case it turns out to be the seals.....

5spdSC300

iTrader: (1)

Yeah i read the thread and it just didn't sound right that it would only last a few seconds if it was constantly sucking up ps steering fluid .

Im not sure how much valve seals on a 1uz would run but im sure it'll put a nice dent in your pocket . When the seals start to go out, oil seeps through them into the combustion chamber. This only happens when the motor is cold. Once the car is fired up, all the oil is burned for a few seconds and stops because the seals start to expand due to the motor warming up.

MJHSC400

I know this is what valve seals do, I just wanted to be sure it wasn't p/s fluid by some tiny chance......

Seals are 4.50 each, so 32*4.5= $145.00 just for the seals-- But the heads don't have to come off, so when your in there you may as well send your exhaust cam off to get it reground with more overlap--

I'm not sure what a mechanic would charge, but $10 ~ $15 per valve seal sounds about right --- $450 ~ $600 for the whole job-- Oh, I forgot the new shims-- they should run another $150 for the proper shims to bring the lash back to spec..

But the good news is if the compression is good, there's no need in swapping the whole motor-- This will get her back in good shape....

A lot of change, but considering a car note is often $450 or way more, it's not too much to spend on a $55,000 car in my opinion.....