Light Colored Smoke

[Hinomotoman]

I just overhauled my Mitsubishi K3M. When the engine is put under load, it pours light colored smoke. It's hard to tell if it's white, blue or a combination. I have 450 lbs. compression on all 3 cylinders. No coolant/oil cross contamination. I did coat the cylinders with 50W motor oil when assembling. It has new pistons, rings and was machined to match the new pistons. The engine has been run about an hour since overhaul. Could this be the oil burning off the cylinders after 1 hour of running? Any ideas?

Eugene

 

[Ilikeurtractor]

Is it possible you could post of video of this? A lot of times smoke analysis can be difficult. It depends on the amount of smoke, engine temp, and even the background you look at the smoke against among a lot of other things. Dark backgrounds will almost always show some white smoke especially on engines not up to "working" temp. Most, if not all of this is water vapor from the combustion process condensing on the way out of the stack and should not cause concern. I wouldn't think there would be any of the 50W oil left on the cylinders that you used for assembly after an hour of run time.

 

[Hinomotoman]

It doesn't smoke unless I'm going up a steep hill or the engine bogs down for some other reason. You can't see through it. It's that thick. If the tractor is sitting still and you run up the RPM's, it doesn't smoke. I have no way of posting a video but it's thick enough to embarrass me in front of the neighbors.

Eugene

 

[Ilikeurtractor]

Would you call it more gray or white?

 

[Hinomotoman]

It's really hard to tell , it's very close to both. If it's grey, it's a very light grey.

Eugene

 

[Ilikeurtractor]

Not really sure what to tell you since your compression is good for each cylinder and we are assuming no coolant getting into the cylinders. Was the smoke purely black before under the same circumstances? Supposedly stuck rings could cause white smoke but I think that should show up in low compression. Maybe even air in the fuel lines but I don't have personal experience with either of those. Bleed the fuel lines one more time to the pump. Other than that I'm thinking I'd run it in some more and keep an eye on it. How does power feel when it's doing this?

 

[aczlan]

Can you do a leakdown test?

Aaron Z

 

[houstonscott]

You might have some oil getting by rings until they seat. Keep rpm's low, don't stay at same rpm for more then 15 minutes. Very speed. Keep loads light for as many hours as you can tolerate. Let those rings seat. Don't put it under heavy loads for 50 hrs. HS

 

[Hinomotoman]

Not really sure what to tell you since your compression is good for each cylinder and we are assuming no coolant getting into the cylinders. Was the smoke purely black before under the same circumstances? Supposedly stuck rings could cause white smoke but I think that should show up in low compression. Maybe even air in the fuel lines but I don't have personal experience with either of those. Bleed the fuel lines one more time to the pump. Other than that I'm thinking I'd run it in some more and keep an eye on it. How does power feel when it's doing this?

I don't know how the engine acted before. I bought it not running knowing it needed an overhaul. It has plenty of power at all stages. The air in the lines might be something to check into. I bled it up to the injection pump and hit the starter to bleed injector lines and it started. It starts in 40 degree weather without the glow plugs.

 

[Hinomotoman]

Can you do a leakdown test?

Aaron Z

I don't have the gauges for it but I will get some. What will that show me?