tvd51

My 91 LS400 with 150K miles currently has smoke at startup. Someone in this forum said that something to do with the idle-up valve on the steering pump. My Lexus dealer told me that they've never heard of that thing before (they think that US model may be different from Canadian model), besides the steering pump in my car is only two years old.
I really want to fix this problem because it's embarrassing to see smoke coming out from such a nice car, but I'm stuck. HELP!
tvd51

Rice

Where is the smoke coming from? Engine bay or tail pipes?
If it's coming from engine bay, then you have some oil seeping onto headers while the car is cold. Once you start it, headers worm up and burn the oil off in the first few minutes.
If it's from tail pipes, then the list of culprits is too long...

tvd51

The smoke comes out from the tail pipes (only at startup after being shut down for several hours). The usual cause of this is that the piston rings are slightly worn out and oil gets to the combustion chamber after the engine stops running. I hope this is not the case because it's expensive to fix and this engine is not supposed to have this problem at 150K.

tvd51

Lexkost

It is the valve seals......after the car is off the oil in the head leaks through the valve seals and into the cylinders and causes the smoke at start up.

tvd51

Yes. The valve seal leak is one of the common causes of smoke at startup. But, is it a common problem for LS400 with 150K miles ?
tvd51

tvd51

Good news: No longer smoking at startup after I installed the EGR vacuum modulator (to fix a different problem). Can anyone explain why ? Thanks.
tvd51

dunn378

what was the original problem you were having that you had to replace the egr modulator and how much was it? also where is it located? thanks.

tvd51

dunn378: The engine check light came on intermittently at highway speed and it turned off days later automatically. The EGR modulator is right in front of the EGR valve (they're both on the driver's side of the intake). The modulator cost CAD 160 (about USD 120), labor is negligible.
tvd51

dunn378

thanks for the info.