Black smoke/RPM question

[Delicious Clint]

New to the forum AND to this style of vehicle (no, I cannot explain WHY I bought it but if you have any insight, feel free....) but am mighty happy to have a great cross-country trip under my belt that got me comfortable with the rig. I'm young enough (early 40's) to have SOME memory of smoky diesel engines but most of my adult life has been spent with very clean diesels. This is obviously not one of them.

I can see and understand the correlation between RPM's and smoke -- my M109 lays down a helluva smokescreen when dropping down to 1500 rpm going uphill. Typical example: hitting a hill on a 2-lane road at 50mph/5th gear/2200rpm. By the time we slowed to 46mph/5th/2000rpm we're putting out a haze. Backing off on the accelerator allows me to drop speed/rpm down to 35/1500 where I can engage 4th gear. If I don't back off, we lay down a pretty good smoke trail (black) lugging the engine over the top of the hill. Yes, it is obvious to me that lugging the engine down under 1200 rpm is awful and I don't do it. Dropping to 4th and hitting the accelerator usually gives a blip of smoke and if it's a moderate grade we'll go right up at 38mph/4th/2000-2200rpm. If we have to drop again it's the same thing....when rpm drops into the teens, we start laying the trail for everyone following behind. When the rpm's are between 2100-2300 we're clean and happy.

In reading the forums I believe I understand this to be fairly normal. The color is fine. The engine is responding as expected and seems to be running great although I think my idle is a little low -- 600-700 when starting/cold.

Is there anything that can be done to minimize the "dirty" look of these engines? It is a bit embarrassing to run around this gorgeous country spewing crap. It certainly makes me more aware of keeping my rpm's in range but the gearing is a bit awkward for that -- this truck could really use additional gears!

This is the perfect truck for what I am going to be doing with it (Baja, Nevada, remote canyon camping with river crossings) and it's function is NOT to be run in the city, anyway. But any input on how to reduce excessive smoking would be much appreciated or any pointers on something that I may well be missing in my inexperience.

Thanks!

 

[Floridianson]

Yea go to resources then to TM's then second page trouble shooting the 465.
There you will learn how to check boost numbers at low end and high end.
Did you or anyone turn up the motor.
Also got to shift and keep it at 2600 through the pull. Drop a gear as soon as you can to put it back on red line when needed.

 

[AaronW]

-- this truck could really use additional gears!

Don't forget you have Low 4th and Low 5th for use in these situations.

 

[WillWagner]

Sounds completely normal. These aren't like modern diesles that like to work down at 12 to 1500 RPM, they like 2000 and above. They smoke, nuttin' you can do about that. If you take into consideration the year the Multi ws made..1980 ish...it is WAY cleaner than the Cat, Cummins, Mack, DD, etc engines that were new then. The truck does definatly need a gear between 3rd and 4th, 1000 RPM is a BIG split.
600 is a bit low. The idle is easily adjusted, should be aruond 800 hot.

Sounds like you have some good plans in store! Before you cross the southern border in it you should check things out first. You might cross into Baja, but not back into the U.S. I have read stories, but it might be just internet gossip.

Welcome! Download the TM's..they are on the old site..and read them. You'll find these are easy to work on and a blast to drive. Wait, you found that out already!

 

[frodobaggins]

Does yours have a turbo ?

 

[DieselBob]

The military installed turbos to help cut down on the smoke screen. Even called them “clean air kit”.

 

[Delicious Clint]

Ahhhhhhhhhh......I begin to see and, no, this is not the turbo model. Just helped a friend pull down his barn and was going through the rpm/smoke correlation with my Lovely GF on the way home, with at-hand examples. It takes some familiarity to jack the RPM's -- frankly, it's easier when using hearing protection because you're listening to the lower note of the engine rather than all the higher noise. I definitely reference the tachometer when driving (as well as having the visual reminder).

So.....taking a non-turbo engine to turbo? My buddy with the barn (errr...ex-barn, post-M109) suggested a propane feed but as a non-engineer I believe this may be outside of my immediate realm of expertise.

Off to the search function for turbo questions....

 

[Delicious Clint]

And thanks to everybody -- your answers are awfully helpful. I've never driven anything quite like this thing and it's good to have the backup. A few years ago we drove a converted city bus down Baja for a surf trip -- better top end, worse low end, same mileage...a little smoother! This is a whole 'nuther ball of wax. Off to research more on the site....looks like I have a new leak on the engine today. I think we might have knocked one of the oil filters loose in Wyoming.

 

[wreckerman893]

Things to remember about diesel engine smoke........white smoke usually indicates oil burning in the cylinder....bad rings or oil getting into combustion chamber from another source..if an engine is "using oil" (you have to constantly add oil to maintain the correct level) it is prob burning oil or you have a bad leak.

Black smoke usually indicates incomplete combustion, either too much fuel or too little air.....have you checked the air filter and made sure it is not clogged. If it looks dirty blow it out with an air hose. Some deuces have an air filter indicator mounted on the dash.....they can fail and give you the impression that you filter is good when in fact it is clogged.

As stated above the turbos were added to reduce smoke not to increase horsepower.

I have a non-turbo M275 and it smokes a lot more than my turbo deuces.

 

[wb1895]

Ditto on the non-turbo deuce. I have a '71 deuce that is a non- turbo, and I just look at it as my contribution to mosquito control