Mystery smoke

[monkey h]

Hello to all

My 4.0 Chim starts smoking from exhaust about 5 mins after start up (blueish maybe but very pale) and then throws out enough smoke at idle to prompt a quizzical look from a passing fire engine. 10 mins later it is all gone and back to normal.

It's noticeably worse if I haven't driven for a couple of weeks

Any ideas would be very welcome

Thanks

[poorpeet]

Are you sure it's smoke & not steam? It takes a while to burn off all the condensation. I'd have thought that if it were burning oil it would smoke a bit all the time I not just while warming up.

[T_Pot]

not sure if the rover engine suffers this, but what you have described is valve stem seals.
oil passes the seals when not used and is burnt off once started.

[monkey h]

Hello T Pot

That seems to make perfect sense.

Thanks for help

[odyssey2200]

On the RH rocker cover of the Rover V8 was a canister type attachment with a rubber pipe on the top which was a crankcase breather.

If it blocks it increases crankcase pressure and can cause a fe problems including making valve stems more likely to allow oil/gasses past.

this breater unscrews and there is a gauze held inside by a large circlip.

Remove the circlip remove the gauze and be shocked at the lumps of smeg caught in it.
Eithere replace the whole thing or clean and repack it.

Another sure sign of this breather being blocked was a leak from the distributor drive on earlier V8s.
Valve stem oil seals or oily gases being pushed past under pressure sound likely to be your poron from what you have described.

[poorpeet]

I would have thought that any oil leaking past the valve stems and into the combustion chamber would burn and cause smoke as soon as the engine starts. It would burn off within a few moments and the smoke would stop.
If all is well for the first few minutes, then it starts to smoke, this points to something in the exhaust burning off as the system heats up.