91 LS400 Valve stem seals.
 

Hello! Is there any one that can guide on how to replace valve stem seals on 91 LS400. My car makes blue smoke on cold start for few seconds and after a while it stops making blue smoke. I have replaced pcv valve and cleaned the throttle body. I notice there is some oil in spark plug well also. It's not burning engine oil. It has 300 k on the clock. Thanks!

disconnect and plug the line going into the front of the intake...see if the smoke on startup goes away

you mean the power steering vacuum line that goes into the intake?

yes...make sure to cap the nipple on the manifold

Yeah you can actually get to it from under the car with a skinny 17 or 18 mm wrench. You don't have a lot of room but it's doable. I just did mine yesterday. You can bypass it and don't see any noticable difference. Plug the intake. And the trick to get get it off is to bust the plastic casing around the valve (only if you dont wanna buy new one) Then you can get the wrench on much easier. Then I took a punch and pushed metal valve through. And since it was memorial day didn't have access to welder. I just filled the valve with jb weld let cure for 10 hours and screwed it back in, so far no leaks.

And the simple fix in most cases is a couple of small orings. And you get to retain the functionality.

yeah it's likely you are actually burning power steering fluid, not engine oil, from the air control valve.

check this out.
https://www.clublexus.com/forums/ls-...ystem-diy.html

After disconnecting the vacuum line that run from power steering to intake did the trick. No wonder the steering fluid use to get low. I thought it has a leak in power steering hose or pump but I looked around and found out there is no leak. I am going to cap off the vacuum lines and also cap off the two prongs of the valve because I don't have time to remove the valve and plug with a bolt. Bad thing is I already bought steering pump with hoses without know the culprit was the valve. I will sell it on eBay at some point.

glad u got it figured out ;)