altitude adjustment on the sd22

[TrouseLife]

I just moved up to Colorado and can't seem to figure out the sweet spot for altitude adjustment on my 82 diesel 720. It has been idling high no matter my adjustment and either blows heavy black smoke at idle and while driving or blows white smoke while idling but not driving.

 

I checked the manual, but it reads "see chart below" without any altitude chart around. Went from ~1000ft in the southeast to 7000ft in Colorado.

 

Just playing around with it each drive into town until I can figure it out.

 

Any suggestions?

 

Thanks in advance.

Trouselife

[datzenmike]

Wayno?

[DanielC]

Wayno probably knows, but I am guessing he lives below 500 feet from sea level.  He may live below 100 feet.

[ggzilla]

170 ft - use the normal setting.

 

Set the locknut and pushrod length to spec, then only turn the adjustment screw.

[MikeRL411]

I just moved up to Colorado and can't seem to figure out the sweet spot for altitude adjustment on my 82 diesel 720. It has been idling high no matter my adjustment and either blows heavy black smoke at idle and while driving or blows white smoke while idling but not driving.

 

I checked the manual, but it reads "see chart below" without any altitude chart around. Went from ~1000ft in the southeast to 7000ft in Colorado.

 

Just playing around with it each drive into town until I can figure it out.

 

Any suggestions?

 

Thanks in advance.

Trouselife

 

For what it's worth, a properly tuned Diesel will puff white smoke at idle and show no smoke under acceleration or in gear.  Diesel mechanics tune engines to this standard then purposely detune to blow black smoke on idle and under acceleration because that's what semi drivers want.  They think it shows more power! 

 

I guess it goes with the "Truckers' Breakfast" served just West of Great Falls Montana.  A loaf of bread,  A side of bacon.  A dozen eggs. A pot of coffee.

[wayno]

I just moved up to Colorado and can't seem to figure out the sweet spot for altitude adjustment on my 82 diesel 720. It has been idling high no matter my adjustment and either blows heavy black smoke at idle and while driving or blows white smoke while idling but not driving.

 

I checked the manual, but it reads "see chart below" without any altitude chart around. Went from ~1000ft in the southeast to 7000ft in Colorado.

 

Just playing around with it each drive into town until I can figure it out.

 

Any suggestions?

 

Thanks in advance.

Trouselife

First thing I would do is check to make sure that the line going from the throttle body/carb looking thing to the injection pump is in good condition and has no leaks from cracks and holes, this is a vacuum line, and when the butterfly valve inside the TB closes, it pulls the injection pump back to idle, if it has a leak from a crack in the line or is loosing vacuum, it will idle weird, because it is being fed fuel but cannot get air.

It will blow black all the time if that hose is compromised, as it will be floored all the time, and it will idle like shit.

There is a smog screw on the side of the injection pump, basically it is for making the fuel mixture richer or leaner, but it sounds like you have other issues to me.

The front injection pump hose is a breather line(open to air), while the back line(closest to oil filter) goes to the TB/carb looking thing.

[Robert]

 

First thing I would do is check to make sure that the line going from the throttle body/carb looking thing to the injection pump is in good condition and has no leaks from cracks and holes, this is a vacuum line, and when the butterfly valve inside the TB closes, it pulls the injection pump back to idle, if it has a leak from a crack in the line or is loosing vacuum, it will idle weird, because it is being fed fuel but cannot get air.

It will blow black all the time if that hose is compromised, as it will be floored all the time, and it will idle like shit.

There is a smog screw on the side of the injection pump, basically it is for making the fuel mixture richer or leaner, but it sounds like you have other issues to me.

The front injection pump hose is a breather line(open to air), while the back line(closest to oil filter) goes to the TB/carb looking thing.

 

 

Are you talking about a new hybrid diesel engine that has a throttle and runs with vacuum?

 

You cannot make a diesel engine idle rich.

[Robert]

This engine should have a high altitude compensator already on it. It is either malfunctioning, missing, or you have other fuel issues.

 

 

 

Black smoke at idle is not altitude related. Is it possible the humidity change is what your noticing?

 

 

How about engine timing?

 

I would check those first. Timing will make black smoke on a diesel. Too much fuel at idle is impossible.

[wayno]

 

 

 

Are you talking about a new hybrid diesel engine that has a throttle and runs with vacuum?

 

You cannot make a diesel engine idle rich.

No I am not talking about the newer hybrid engines, I am talking about the inline injection pump on the US model 720 1981-86 SD22/25 series diesel engines, the throttle is run by vacuum, if you unplug the line going to the throttle body while the engine is running, the engine will start running like crap, it will sound like it wants to run away, but it cannot get air, so it will blow mass amounts of black smoke, as the injection pump will be floored because the line was removed, but it cannot get any air because the pedal is not being pressed.

The SD series engines in the US do not have a throttle cable going to the injection pump, there are no cables of any type going to the inline injection pump, only one vacuum hose, and one vent hose, it has a diaphragm that controls the throttle.

[Robert]

 

No I am not talking about the newer hybrid engines, I am talking about the inline injection pump on the US model 720 1981-86 SD22/25 series diesel engines, the throttle is run by vacuum, if you unplug the line going to the throttle body while the engine is running, the engine will start running like crap, it will sound like it wants to run away, but it cannot get air, so it will blow mass amounts of black smoke, as the injection pump will be floored because the line was removed, but it cannot get any air because the pedal is not being pressed.

The SD series engines in the US do not have a throttle cable going to the injection pump, there are no cables of any type going to the inline injection pump, only one vacuum hose, and one vent hose, it has a diaphragm that controls the throttle.

 

 

Ya, that the one I am talking about. Seen one not long ago, and it throws the diesel mechanics for a loop as it did me. We joked about it being a new Hybrid although they are old.

 

These do have a high altitude valve and should not need adjusting when you drive from point a to point b though.

 

IF it is not correct when he moved to Denver, then the valve is bad. I am sure you know that diesels are not as easy to adjust mixture as gas and since he already moved the adjuster, replacing the Alt valve will not fix his problems anymore....it needs to be taken to a Diesel mechanic and properly adjusted after replacing whaveter parts not working.

 

 

Oh, just to add....yes you are right on the vaccum line and that would definately be the simpliest check, but it would not have run properly before he moved.... Thats why i am thinking its more than the hose.

[Robert]

 

I just moved up to Colorado and can't seem to figure out the sweet spot for altitude adjustment on my 82 diesel 720. It has been idling high no matter my adjustment and either blows heavy black smoke at idle and while driving or blows white smoke while idling but not driving.

 

I checked the manual, but it reads "see chart below" without any altitude chart around. Went from ~1000ft in the southeast to 7000ft in Colorado.

 

Just playing around with it each drive into town until I can figure it out.

 

Any suggestions?

 

Thanks in advance.

Trouselife

 

If its blowing black smoke sometimes and not others as you say, I would say its not needing adjustment. Like the gentleman above says, check hoses for leaks. There is a Altitude compensator on your engine and should be able to be driven to different altitudes without having to go to a mechanic and adjust the pump. If it were myself, I would replace hoses, change the compensator, and adjust the pump to book specs.

 

BTW, would you like to sell it? I have been trying to get one of these for a while but everyone i meet that has one wont sell the damn things. Sheesh...people and their babies.

[TrouseLife]

So i didn't find any bad looking spots in the IP vacuum line, but I'll drop by napa after work to pick up some fresh rubber vac line to see if that helps any.

 

As I've continued tinkering, I've gotten a large cloud of white smoke every crank and on idle. Only getting black smoke while climbing hills now.

[Robert]

 

So i didn't find any bad looking spots in the IP vacuum line, but I'll drop by napa after work to pick up some fresh rubber vac line to see if that helps any.

 

As I've continued tinkering, I've gotten a large cloud of white smoke every crank and on idle. Only getting black smoke while climbing hills now.

 

 

Well I would like to say its the colder dryer air in Colorado that your noticing the moister in the exhaust...but "large clouds" may be signs other more serious problems. Keep an eye on the radiator fluid level.

 

Does it smoke white when warmed up?

Black smoke upon hills not uncommon but depends on how much.

 

Sounds like you may notice these things now that your in a higher altitude and not that they are abnormal. Altitude valve may have been stuck and now losened. But I am guessing here.

 

 

 

These guys in this forum work on those motors alot.....down a ways they explain how the motor adjusts to altitude and repairing of those issues.

 

http://www.binderplanet.com/forums/showthread.php?t=32773

[ggzilla]

Nissan SD engines used two different injection pumps. The common type has a manually adjustable altitude compensator.

[Robert]

 

Nissan SD engines used two different injection pumps. The common type has a manually adjustable altitude compensator.

 

 

I would disagree.

 

Couldnt find a model without one, and all from Cali. are equipped. I would say it has one, and they are more common. Maybe the Fork Truck engines may be absent of one, but ours here has it. Its a smog control device.

[wayno]

 

 

 

I would disagree.

 

Couldnt find a model without one, and all from Cali. are equipped. I would say it has one, and they are more common. Maybe the Fork Truck engines may be absent of one, but ours here has it. Its a smog control device.

What are you disagreeing with here, as I can prove there are 2 kinds of injection pumps, here is a common inline.

 

 

and here is a VE type.

 

I don't know about the VE type, as I have not really looked it over real close, but the inline pump is fairly simple on the outside, so maybe you could take a photo of the altitude adjustment screw or whatever it is and enlighten me.

This is the smoke screw, it makes the engine run richer and leaner.

 

There are not a lot of things on these pumps to adjust externally.

[TrouseLife]

Wayno, I cant say I know what Robert is talking about, but I've definitely got an inline IP. Ill get a paycheck tomorrow and see about finally buying some new vac hose.

 

Also, my engine manual mentions multiple styles of IPs. Just saying.

 

Every start of the engine is getting more difficult (taking three or four runs of the glow plugs and at least two times to hit the starter), and there is no time between cranking, warning, and driving that I'm not blowing a cloud of smoke... either white or black.

[wayno]

Did you overheat the engine?

How old are the glow plugs?

I have had a couple engines that were just wore out, they smoked badly upon start up, they would not stop smoking, and it smelt weird, I overheated one, that one was never the same after that, I removed that engine and put a rebuilt one I had in the truck, I plan on rebuilding that engine, as it is a SD25.

Here is a couple photos of the smoke.

 

I will admit that this engine even though a SD25 was a gutless wonder, it had no more power than a SD22, I suspect that it was because veggie oil was put through it for a while, it's very hard on the injection pumps, one day I will compression test it, and decide what to do after that.

There are a lot of reasons why you can have the issues you are having, I don't know all of them, but if that vacuum hose has a crack/hole in it, it will cause a rich issue as the injection pump will be partially or fully floored, it needs vacuum to be pulled back to the idle position, also there is a diaphragm that is controlled by the vacuum line that could have cracked or have a hole in it now which will cause the same issue, as air escaping past the diaphragm will also let it move to the floored position.

Keep this in mind, when the engine is not running, the injection pump is floored, as there is no vacuum, if the hose going to the venturi in the carb looking thing is compromised, it will not have vacuum at the injection pump, so it will be floored, if the diaphragm is compromised, it will have low or no vacuum control and the injection pump will be partially or all the way floored, if the venturi is plugged it will not create vacuum, and the injection pump will be floored.

The injection pump throttle control is very touchy, very little movement makes a big difference, there is a plug between the 2 lines connected to the injection pump, in the photo below is a pump partially pulled apart, just to the left of the vent line is a bolt with a phillips screwdriver head, this is where you are supposed to fill the cavity in the injection pump with cod liver oil, I am not completely sure of the reason why it is filled, but I suspect that it keeps the diaphragm soft, and it is likely also a dampener.

I cannot claim to know a lot about these engines, I seem to know enough to get them running, and enough to be able to figure out fuel starvation issues, I even rebuilt one, and it runs(the green engine in the photos above), low compression, wore out injection pumps, and bad glow plugs will give you headaches.