Blue exhaust smoke on cold starts

[tommyweaves]

Hi all

My 55 plate 2.0tdi manual has now done 57k. It's always been a bit smokey on start up when cold, i.e. in the morning, but today I noticed it was getting a bit much. By that I mean I had a cloud of blue smoke, not really excessive, but enough to notice through the rear view mirror. I don't notice any blue smoke when driving (although when you're travelling it tends to disperse more and it's less noticeable) and I don't use an excessive amount of oil, about 1 litre every 10k miles.

As it's coming up to the 60k warranty mark I thought I'd canvas opinion from my knowledgable associates (that's you guys by the way).

I'm assuming it's a bit of oil (it doesn't take much oil to produce blue exhaust fumes) getting in the hot areas when it's been stood overnight. Usual suspects would be valve stem oil seals (although there's no smoke on the over-run that I'd expect with worn valve guides and seals etc) or maybe turbo oil seals.

Anyone have similar experience or got a view?

(comments from France welcome! )

[Quatrelle]

Hi Tommy!!

Couple of thoughts:
1, is the smoke on start up definitely blue and not grey (i.e. unburnt fuel)? Try leaving the ignition on for about 5-10 secs next cold start to make sure the glow-plugs are getting really hot. It's certainly the case with our Laguna. If you're still getting smoke that shoots this one down.
2, blue smoke on the overrun is usually worn bores - with the throttle shut the engine has to suck from somewhere so it tries to bring oil up from the sump. If you let it idle for a while when hot and then rev the engine, blue smoke is definitely the valve stem oil seals.

Caveat - both the above were valid about 20 years ago, but things might have changed since I last dropped a sump.

[tommyweaves]

Hi Tommy!!

Couple of thoughts:
1, is the smoke on start up definitely blue and not grey (i.e. unburnt fuel)? Try leaving the ignition on for about 5-10 secs next cold start to make sure the glow-plugs are getting really hot. It's certainly the case with our Laguna. If you're still getting smoke that shoots this one down.
2, blue smoke on the overrun is usually worn bores - with the throttle shut the engine has to suck from somewhere so it tries to bring oil up from the sump. If you let it idle for a while when hot and then rev the engine, blue smoke is definitely the valve stem oil seals.

Caveat - both the above were valid about 20 years ago, but things might have changed since I last dropped a sump.

Hi Quatrelle

Definitely blue, my first car was a mini and I got through 5 engines so had a bit of experience on different smoke signals! Hear what you're saying on bores and valve stem oil seals, but I'd expect more blue smoke than I'm getting if either of those were the cause.

Thining of videoing the next morning start up and posting it!

[Quatrelle]

Tommy

Started our 12-year-old Laguna this evening - reached in, turned the key after waiting for the glowplug light to go out, and it started idling (in other words didn't touch the throttle), and then left it idling for a few minutes. When I eventually drove off there was quite a lot of smoke for the first fifty yards, and I have to say it looked more blue than grey. I'm sure it wasn't oil - although it's done 170,000kms I never have to top it up between changes - I'm thinking products of incomplete combustion.

The plugs are turned off after a few minutes, and leaving it idling as I did obviously didn't get the engine hot enough to allow compression-ignition to work properly after they'd gone off.

Don't know if that helps, just another thought.