blue smoke revisited

[GMichaels]

Since it has gotten cold my truck when first started smokes pretty bad. after about 20 min it will clear up. when it is warm out will smoke a little then clear up in about 5 min.



When I asked this question before the conclusion was injectors.



I am about to purchase some stock used injectors, but do not want to go throught the expense and time of changing them and end up with the same problem.



Could this be a problem of low compression when cold and the diesel fuel is not burning fully? When first starting and weather is 40 degrees or below the truck will smoke and will run rough.



what do you think still injectors?



1993 dodge, 360get, 354 no mods

 

[KWeber]

From what i've read it sounds like the timing is not advanced enough.

BTW, why are you installing stock used injectors, instead of upgrading?

 

[Bob Beauchaine]

Sounds like timing might be too advanced. The KSB solenoid advances timing about 5 degrees when the engine is cold. You might try disconnecting the wire from it after you start it but when it's still cold. Then drive it and see what the smoke is like - if it's reduced then advanced timing is probably the culpert. The KSB solenoid is on the drivers side of the pump and has 1 wire running to it. Good Luck.

Bob

 

[WashingtonFLHTRider]

Having not see the first post I would ask the following questions.

Are your grid heaters working properly?
Are you letting the truck idle for long periods of time waiting for it too warm up?
How many miles are on the truck?
How cold is "cold"?

Just for grins I unplugged my grid heater relays the other morning. 28 deg outside. Smoked just like my ol' BC3 400 Cummins. Hook them back up and very little smoke.

These engines require some load to start warming up (more so the colder it gets out). Not meaning people should go out and hammer on them when cold, but working them lightly until you start to build a little heat.

I have heard that turning on your exhaust brake will speed up warm up times. I don't have one so I don't know.

I would not bother with the used injectors unless your getting a good deal on them. If you are then find yourself a local diesel shop that does injector work. Have them checked out, cleaned & snap checked as needed.

I fought a smoke problem on my 3406B CAT engine for sometime. After rebuilding the engine we thought it must be a fuel problem. Well come to find out it was low cylinder presure when cold. The exhaust valves on the back two holes were leaking and causing my cold smoke. Infrared heat gun pointed at all 6 holes and comparing the temps comfirmed we had a problem.

So yes it could be your injectors. It could be your injectors combined with another problem. If it is a high mileage engine you could have 2 or 3 things combining to make it worse.

 

[Mopar Man1]

I'm having the exact same problem on my 93 D350 CTD 5spd. Doing it in time inverals just like your truck too! I don't see how it could be injectors on my truck seeing how it's been took very good care of and it only has 88k on it My grid heaters work on mine,they kicked on a few mornings ago when it was real cold out. I checked,I do not believe that my truck has been turned up what-so-ever so I don't see how it could be the timing(but it may have been turned up but it don't smoke like it and the pump doesn't look like its been messed with. It don't see to be hurting the motor at all but *shrugs* Help me and this ole boy out



Jimmy

 

[BushWakr - RIP]

Please, if you're going to spend some $$$ on injectors, get some upgrades... it really is worth the money. If you go that route you can keep your stock ones, have them cleaned and reset and put away for future need. BTW, have the pop off pressure raised to about 255 or 260 bar tool. (stock they are 245 I believe)



The problem(s) you describe can be injector related but indirectly in my opinion... if you have some bad injectors that are, say, sticking, then you have in effect retarted your timing due to the delay in opening. That coupled with the poor injection quality/cloud will cause coarse fuel to enter a cylinder that is basically cold to begin with.

That is why the KSB is used. It not only increases the injection pressure but it also forces the timing into "advance" setting by changing the relationship between cam and roller ring start point.



The symptoms you describe don't really seem like injector problems on the surface though... the fact that the conditions and symptoms are affected so noticably eg:20 min/5 min. kind of thing. .



My first thought's would be to confirm/re-confirm the function on your KSB;grid heater relays;grid heater elements.

Next would be the timing issue... your situation really seems to rest in this general area...

While there can be some variance here... normally the slots in the inj. pump flange will only allow so much advance.

I'd guess that about 17-18* advance is attainable using the pump rotation method, couple that with roughly 5* advance provided by the KSB/mechanical piston advance and you are at an approx max timing of 22'ish degrees.

That is a fair bit, but not enough to cause the problems you are having... . at least I don't think so. . hmmmmmm... bob, do you agree or no???



Once you've checked the items above then I'd run a major dose of fuel additive. Aim for something with good detergent content and high cetane improver.

That will serve two functions... one, obviously, to clean out the system from the pump right through to the injectors... sometimes even the delivery valves can get contaminated by crappy fuel.

Secondly the cetane improver is going to eliminate poor fuel grade cetane value and improve the burn quality of the fuel so that you'll be able to rule out the incomplete burn symptom... . that can cause some of the smoke and issue's you are having in my opinion.



Are we correct in assuming your lift pump is ok???

It should provide about 8psi at idle and no less than 3psi at WOT (that's according to "the book")



pb...

 

[GMichaels]

ok, I plan to purchase used stock injectors due to lack of money, will cost about 100. 00 for used. Seems like upgrades are about $400. 00 and up, would love to upgrade, but need to determine the condition of this engine first and then save some money.



The mileage on the truck is 277k... maybe more, don't know for sure.



Grid heaters appear to worrk, can hear the click of the relay and the volt meter dips. what is the best way to check this out?



cold is 40 or below, looks like a smoke bomb (at idle) and runs rough at this temp



I will have to do some reading on the KSB solenoid, will disconnect and report back with results.



I will have to check the lift pump.



I will try the fuel additive with certane ??? improver, Now I may still have some summer blend fuel in the tank. .





so looks like grid heaters, ksb.



One thing that maybe related is when first starting the truck will idle at 750, after it gets warm will idle around 900, was going to ask about this down the road...



Thanks

 

[JLEONARD]

One thing that maybe related is when first starting the truck will idle at 750, after it gets warm will idle around 900, was going to ask about this down the road...

When the cylinders are cold they cannot combust all the fuel... hence the smoke and the "low" idle speed. When the cylinders warm up enough to burn it all, the idle naturally goes up as the smoke clears.

Drippy or "lazy" injectors that no longer give a god spray pattern will accentuate this.

 

[Bob Beauchaine]

I see that you've got 277K on your truck - your pump could be near the end of it's useful life. Thus it could be getting sloppy inside - these pumps don't usually give a lot of warning before they go. At 30 to 40 degrees I see some white smoke for 3 to 5 minutes and thats all and I, like Bushwacker, run some pretty serious advance. When I first start my truck at 32 degrees and under it will run rough for about 30 seconds then it smooths out and runs normally. I agree with Pastor Bob that - non or poorly functioning grid heaters coupled with too much advance could be a problem. Try the cheap ( $$$ ) fixes first and see what happens. Once again good luck.



Bob