Smoking with 15w40, no smoking with 10w40 !
Turbo Mini Forums

Hi,
I don't have stem seals on the valves, I could not install them with SW5 (10mm lift) and intake guides installed 3mm higher.

The engine smokes in idle (after a minute) with 15w40 but does not smoke with 10w40. I had 10w40, then changed to 15w40 and then after 1000km changed back to 10w40.

How to explain that ?

The idle intake pressure is exactly the same, 26-30kpa depending on electric devices switched on.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

could the 10w40 be running out of the head faster cos its thinner ,so it doesnt sit around the guide so much ?

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

this seems silly to me, no seals fitted what guides do you have in??? what make
also what springs are you running ?????

i have run lifts much higher than this with NO! problems whatsoever

Why have you installed the guides 3mm higher ?

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Guides are new std for a std 998 head (std valves and the rest). They were "bored" to get 0.05mm play, as they collapse during installation (done by a workshop).

Springs are double from Swift they sell for SW5. I don't see relation between smoke and springs.

I installed them higher to free the air passage a little bit. Only the intake side. And I forgot that I needed 2mm for seals :) .

I also suspect the thinner oil evaporates faster, but even leaving idle for 5 minutes and then accelerating hard does make any smoke. I'm not sad but I'd like to understand.

It's not the turbo, I rebuilt it and I took it apart once, there were oil in the head but absolutely nothing in the turbo and intake.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

the engine is seeing vacuum on idle and with no stem seals on the intake valves the vacuum will be drawing the oil thro the guides i suspect, i never fitted exhasust stem seals on turbo head with the fatter valves but you defo should have them on the intakes.

no longer a series, but still 1.3 turbo.

Finally physical laws came back :).
We had 2 hot days and engine started smoking in idle. But much less than with 15w40.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm