puff of blue-ish smoke on startup

[saskak]

Hi all,

If this goes through it will probably be the first post after quite a few weeks! Many thanks to the new super moderator for fixing the thread posting.

I am trying to figure out the puff of blue-ish smoke that comes out (exhaust) at cold start. The car is Pug Partner (2007, 1.6HDi, 9HXC engine no FAP, ~90,000miles).

Whenever I start, from cold, there is the puff of blue smoke that clears within 1-2sec, a relatively substantial puff. Starting from warm engine, nothing. Occasionally (more frequently than not), there is judder or rough idle for ~1-2min when starting from cold (say after an overnight start) and everything clears when engine reaches operating temperature. Start is pretty much faultless, irrespective of weather temperature. I suspected glow plugs, but replaced all 4 of them, still the same puff. I had previously replaced the glow plugs relay, so that could have gone. There are no errors with diagbox.

There is no smoke under acceleration or high rpm, of course there is the normal bit of black smoke on very hard acceleration. It has not consumed oil from the last oil change and I did not overfill the oil, i.e. 3 bars below the max. I replaced all filters (oil, air, diesel) and oil ~6 months ago. The smoke and the filters do not coincide.

I was thinking that it is the PCV, replaced the valve (only the rubber diaphragm), but that did not solve anything. Also, it does not seem that there is an excessive blow-by by removing the oil filler cap.
Thus, the logical conclusion is that the valve stem seals are seeping a bit of oil. As far as I understand, the head bolts need removing in order to get to the stem seals or am I mistaken? That would probably require quite a bit of work.

Many thanks for any suggestions.

Cheers,
saskak

[cancunia]

Yes, good of Apollo to shoot a golden arrow

If you're not using oil, then it's probably not oil? The smoke is blue not black?

[saskak]

Yes, good of Apollo to shoot a golden arrow :-)

If you're not using oil, then it's probably not oil? The smoke is blue not black?

Yep, smoke is pretty much blue. Well, not dark blue, but definitely has a blue tinge and not black.
ASAIK a few drops of oil through the stem seals would produce quite a bit of blue-ish smoke, it does not need to be massive oil losses. I cannot distinguish loss of 1/3mm on the dipstick, which will probably equate to 200-300ml, probably less actually, but still a substantial amount of oil.

[cancunia]

Maybe worth waiting until it gets a bit warmer out and see if it persists.
What weight / spec oil are you using?

[saskak]

Maybe worth waiting until it gets a bit warmer out and see if it persists.
What weight / spec oil are you using?

I think it is going on for ~1-2 years now. Still does not loose oil in between service intervals. I do the Total Ineo quartz 5w30, the low sap one. I bet if I go to 5w40 it will disappear.

[GraemeT]

Hi saskak - ours does the same as yours, blue smoke/lumpy for a few seconds from cold. Oil levels fine. I just live with it and it's done 20,000 miles like this since we bought it. Passed emissions at last MoT just fine.

[saskak]

Hi saskak - ours does the same as yours, blue smoke/lumpy for a few seconds from cold. Oil levels fine. I just live with it and it's done 20,000 miles like this since we bought it. Passed emissions at last MoT just fine.

Thanks GraemeT, much appreciated. It did not used to do this. It kind of started ~1-2 years ago.
Slightly embarrassing in the morning on the driveway. It is probably valve stem seals, but quite a bit of work to get them right.

[V6BOY]

My 2007 1.6HDI has done the exact same since I bought it from 30k I guess it's slightly leaking valve stem sills.

[saskak]

Has anyone tried any of the re-seal (snake oil) oil additives? Something in the line of Wynn's Engine Stop Leak. I was thinking that it is designed exactly for exactly this, i.e. rubber components.

[cancunia]

The only snake oil I've ever used so far was on my MX5 to stop the tappet adjusters rattling when the engine is hot. It was Wynn's IIRC & did the job, not sure if that helps tho. I've since discovered that using better oil did exactly the same thing, by better I mean semi-synth as opposed to Dino.
I currently have 5W/30 in mine too but I have 5L of ECP's finest 5W/40 fully synth waiting to go into my Berlingo for the summer. According to the oil spec & my service booklet it's correct for a non DPF 1.6HDi, 5W/30 is also good, but is somehow linked to better fuel economy.
People's opinions differ, but FWIW I think a slightly heavier oil is not a bad thing for higher mileage engines in warmer weather.