Smoky Jimny

My nice Danish friends pointed out to me that my Jimny released some smoke after going downhill using the engine and low gears to reduce speed down the many hills on our trip a few weeks back. The engine oil level has gone from full to low on the 3000km's since before the trip and the last oil change, so I am thinking it could be the valve stems leaking. I have used a Castrol fully synthetic oil so will try to change it soon for something better, but i fear the inevitable job of doing the stem gaskets. Is this common on the m16?

I did run it too long on the oil change before this, did not make a note of the km spent on that oil change, but could be two years and 16000km's. Regret not being nice enough to the engine.

A quick compression test will tell you if it's the stem seals or something more serious. You can do the seals without taking the head off. Disconnect the battery, remove the rocker cover , then one cylinder at a time take the sparkplug out, drop piston to BDC, and patiently feed 2 meters of 6mm flexible rope in through the sparkplug hole, bring the piston back up towards TDC until the engine locks, your valves for that cylinder are now locked in situ by the rope so you can now replace the seals without the valves dropping. A good quality nylon rope is best as it won't fray.

Rope is a good tip, sounds way easier than a air pressure tool.
Car still runs very well by the way. it pulls off uphills way better then other jimnys even with my trailer.

Will try to borrow a compression tester to rule out the piston rings and valves, good tip, thanks!

Check the easy stuff first - are the PCV pipes clear, and is the one-way valve working? 

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Check the easy stuff first - are the PCV pipes clear, and is the one-way valve working? 

Aha! Yes I was wondering about this, if they could play a part in regulating the pressure making the engine suck more oil in.
Must admit i do not fully understand their function, and they where very clogged and then cleaned when doing the engine swap. 
Will check!
Do they clog more from driving more with low rpms?  The car now has way better low rpm torque so do not need to shift down as much as before and generally it is in fifth from 60kmt and up. Even overtaking often in fifth. Do rev it up and drive "hard" as well, but mostly day to day is in fifth gear. and my long drives this summer with a trailer and loaded with camping gear as well..
Could the m13 ECU and the m16 engine also make the m13 valve and pipe clog more easily?

I can't add much to diagnosis but I do firmly believe in the advantages of an Italian tune up, aka giving it opportunity to visit the redline in the first 3 gears every so often. A good thrash down the local dual carriage way works wonders.

it gets that ever so often, but I'm 53 years old

Edit: And the nearest local dual carriage way is only 5 hours from here haha. (If not counting the very steep uphill in the under sea tunnel)

If the PCV breathers are blocked, it can do funny things - in theory the crankcase should normally have a small through airflow from the clean air intake tract, into one side of the rocker cover, and out to the intake manifold (lower pressure sucks it through because of the presence of the throttle valve). At higher loads, blow-by increaes crankcase pressure and it only blows one way.

If the system is clogged, oil mist gets forced where it shouldn't, you get oil leaks, or odd idling problems because the metered airflow is no longer correct.

As it's only a couple of hoses and a ball valve, it's easy enough to check and flush with carb cleaner if necessary.

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it gets that ever so often, but I'm 53 years old

Edit: And the nearest local dual carriage way is only 5 hours from here haha. (If not counting the very steep uphill in the under sea tunnel)

The more I learn about where you live the more I think I should learn Norwegian and emigrate! But then I remember the laws and rules you have to endure when you want to modify your Jimny.