Blue smoke on start up? 4jb1 isuzu mu. Help

[32theworld]

Hi, I have a 1990 isuzu mu, 4jb1 2.8t manual, only done 200 thousand Ks so not bad for a old mu, been well looked after by the looks. But on start up in the morning I'm getting blue smoke? Goes away after 20 seconds of driving? Valve stem seals or rings?? Any help appreciated, also is there anything I can do to help it in the mean time?

[geeves]

When cold diesel smoke can apear blue and the 4jb1 is known for smoke cold. It might not be cause for panic.
What does it smell like?
Whats oil consumption like? If its less than a litre between oil changes dont worry about it
Most common cause of smoke on start up in an old diesel is a leaky injector letting a little fuel into the cylinder when parked This doesnt burn properly when you start the car so you get a big puff of smoke. Next most common thing is the timing but today it should be cold enough for the cold start to advance the timing so you might get no smoke

[Downhillnz]

I notice the same on mine. A lot more noticeable on cold mornings. Its far more prominent if the pump timing is on the retarded side, but it would also be harder to start than the normal half a wind.
It shouldn't miss or hesitate, if it is there might be something more amiss.

I wouldn't stress regardless unless like Geeves said, its burning a good amount of oil. Advancing the pump a little might help, helped with my Mu but that motor was very tired.

[magicdeo]

I have the same issue with my 97 4JB1T rodeo. It blows blue smoke until the engine gets to full operating temp. I wouldnt be worried if it was only for 10 seconds or so but its a bit embarrassing when it goes on for so long. I was also thinking that it could be valve stem seals?

[geeves]

sniff it. The answer will be obvious. They say oil burns blue and fuel black or sometimes white but they forget diesel is an oil so can also burn blue but the smell is unmistakable.
If oil use is minimal then diesel is next most likely

[magicdeo]

Ok thanks Geeves. Between 5000km services the oil will reduce to about half way between the high and low marks on the dip stick which i didnt think is too bad? Lets assume its diesel, why would it blow smoke for so long and not just a minute or so? Ive had people follow me when im fully loaded with firewood when the engine is hot and I can work it hard and they say it doesnt blow smoke, yet when cold it smokes for over 5 minutes. The colder it is the worse it gets too. Its not a glow plug issue as they are all fine and it gets a full glow

[geeves]

The reason is that its a 4jb. 8 out of every 10 do the same thing. New injectors and a pump service will fix it but thats an expensive repair for something that doesnt really matter unless you fail a roadworthy test