Blue smoke!

[Antharro]

Hi forum,

Over the last couple of years, my LS430 has occasionally put out a couple of seconds of blue smoke at start-up. It clears quickly and seems to be fine for a while. Once it smoked for several seconds, again at start, but it has never done that again. I hadn't thought about it until I was driving up the M3 today. I needed to accelerate hard out of a tight situation so put my foot down. The box shifted down as normal but once the revs got up, an amount of blue smoke came out of the exhaust, heavy enough that both lanes dropped back a little. It cleared within a few seconds and did not do it again for the remaining journey up to London, or on the journey back, where it behaved itself perfectly.

It hasn't had an oil change in a while, but what's in there is a decent colour and there's enough of it. The only other thing I've noticed is there is a very slight top end tap, like a tappet or valve tap. It's only really noticeable under acceleration. It still sounds quite lovely at higher rpms!

I've also found fuel consumption is down; I would expect around 25-27mpg on a motorway run - I once got 30mpg on a run to Gatwick and back to Dorset in the middle of the night! Currently it's getting around 23-24 on a motorway run.

I've read up on both this forum and the US forum, and it would seem to be either valve stem seals or the PCV valve (or both?) - what does the forum think? The car has 161k miles.

Thanks!

[The-Acre]

A PCV valve is a simple job but with a rattle it does sound like top end wear. It's vital that these engines have their regular 6k oil change so if that's not been done over the years you may be in trouble.  I once had an LS 400 that puffed blue smoke on startup then I discovered the oil hadn't been changed in 4 years so it went back for a refund.