smoking 3.4L engine after highway run

[okkanui Lurker Find all posts View Profile Close okkanui]

I had a similar problem occurring on my 120 petrol (a few years back when I had it). Turned out to valve stem seal wear. After the engine had been running for a while the oil is more "runnier", which allows it to seep past the valve stem seals and into cylinders after you turn engine off. Hence why the initial smokiness when you next start.

Another indicator of valve stem seal wear is that the engine will also smoke a little when you lift your foot off the accelerator because of the higher vacuum that results from intake air-flow being restricted.

[shawie Lurker Find all posts View Profile Close shawie]

I had a compression test done on mine in April as we had just got back from a massive trip to the middle of QLD from Wollongong and it passed. It's funny it did the same thing again after a week away with the camper trailer last week id be interested to hear how you went Simon.
Thanks

Craig

[Adelgigs Lurker Find all posts View Profile Close Adelgigs]

Thanks for the comments guys.
After driving 7+ hours driving on the weekend with new plugs and a decent dose of injector cleaner in the tank, it appears a whole lot better. No major smoking although still a bit on a cold start. As mentioned above the cleaner wont have any major effect for some time but I reckon the plugs will have helped (perhaps weak spark and unburnt fuel going out the back). The wear on the old plugs was amazing. No noticeable drop in oil dip stick level.
But no doubt a compression or leak down test will tell the tale, but I'll run it for a bit and monitor what goes. I've also got a timing belt and water pump kit to put in when I find time.

Simon

[croozza Avid PP Poster! Find all posts View Profile Close croozza]

The compression test will not tell you about bad fuel injectors, The white smoke is fuel, this will not show up in a compression test, you are just throwing money out by doing it. You are better off spending that money on a professional job with cleaning the injectors ultrasonically