JD 750 White Smoke

[Rockyroad]

I have an 86 JD750. For the past year or so, it puffs white smoke when it is idiling. When the engine comes up to speed, or is under a load, it stops and no smoke at all comes out of it. Anyone out there had any experience with this or can give any hints as to what needs adjusting.

 

[Steve_in_Ont]

From a previous and related posting on making smoke...

"as GlueGuy mentions - It is a combination of factors. One more is:

Low emissions engines ironically will tend to produce more visible smoke at start up. This is due to higher injection pressures (cleaner burn when everything is warm, but almost "puts out the fire" when the engine is cold) and retared injection timing (reduces NOx, but leads to incomplete combustion when the engine is cold). Currently off-highway engines do not need to meet the same tough emissions standards of on-highway engines. Starting in 2006 (and phased in after that based on engine HP) off-highway emissions standards will be much more like on-highway (The EPA term is "Tier III").

One more thing about white smoke at startup - In moderation, it's not really anything to be concerned about... As long as it goes away as the engine gets warm. If an engine makes white smoke in operating conditions, then there is something wrong. In extremely cold climates, the intake air can be soooo cold that this is a problem. Generally, by re-diverting the intake air to use underhood (and slightly warmed) air, this problem is gone (There is a thread in this section on "warm intake air")

Blue smoke is burned oil. Also, at low levels not a huge issue on a cold engine, but it should go away almost right away on newer engines. Older diesel engines are generally designed around a slight continued consumption of oil (The stated oil consumption on 1965 Cat 977 is 1 gallon in 8 hours of use).

While we're on smoke - Black is partially burned fuel. Many people think of black smoke as a sign that a diesel is really putting out the power... However, it is really a sign that there is too much fuel for the amount of oxygen in the cylinder... And it's just wasted. "

 

[Rockyroad]

What it is doing is puffing white smoke when idiling, even after the engine is warm. When you first accelerate with the tractor, it will put out white smoke for a second or so, then it goes away as the engine rpm's come up. It does not put out any smoke when engine rpm's are up or there is a load on the engine. I have about 600 hours on the tractor, but I have not had the valves adjusted. Could that be the problem?

The engine does not lack power and it runs very smoothly - no hesitations, etc. The engine is a 3 cyl Yanmar.

Thanks for the reply. Any other info on this will be greatly appreciated. I will also look around on the site for the discussions you mentioned.