Blue/ white smoke ISX15

[Therealarw]

Hi everyone,

I currently have a truck that is giving me some issues.. I have a Cummins ISX2350 that has NOT been deleted and the driver has been telling me that it's puffing blue and white smoke out of the exhaust and will regen quite often. It had an injector code so I had just replaced it just to make sure because blue and white smoke would be raw diesel right? I've also heard of anti freeze being a possible issue to? Where would I start with something like this? ECM hasn't been altered in anyway and neither is the exhaust. No other codes are active by the way. Thanks in advance for the help also Rawze Community.

[tree98]

I would start by pulling the aftertreatment system apart and inspecting the DPF and DOC. The DPF is likely cracked if it's puffing smoke. You're either going to have to replace the DPF or at the very least get it baked and flow tested so either way it's gotta come off.

The DPF collects the smoke that the engine is producing, while you have the cans off, start the engine and see how much smoke the engine is actually producing. Might be a lot more than you thought.

Having a look at the face of the DPF can tell you a lot about the possible source of the smoke your seeing.Blue colored smoke is likely from burning oil, does it use quite a bit of oil ?Take pictures of the DPF face and post them here.

Has it been using coolant?

Will the engine pass a leakdown test using insite?? That's extremely important on these common rail engines.

Leaky injectors can cause severe damage, everything from heavy fuel impingement to catastrophic fuel pump failure.

Also don't use aftermarket injectors!! That's a huge mistake on an ISX, I know they are expensive from Cummins but trust me it's worth it in the long run.

How many miles are on this engine? The fuel pumps need rebuilt every 400K miles too by the way.

There's a list of things that will get you started.

[JimT]

When does it smoke? All the time or only while attempting to regen? Is it a few puffs of smoke or a full blown smoke screen? Mostly white/light grey smoke with a slight bluish tint is probably fuel. Heavy blue smoke usually oil. White smoke without a blue haze might be water/coolant or just a heavy ash load from the DPF. You'll also be able to smell the partially burnt fuel at or around the exhaust. Even after the fact as the unburnt fuel vapor tends to 'cling' to the surroundings, especially on a weed burner exhaust.

In addition to what Tree listed above there are a lot of things that could cause fuel smoke, including a leaking doser (7th) injector, a DOC that's no longer functioning properly, an otherwise properly functioning system EXCEPT for an exhaust leak prior to the DOC.

It's also possible that you have more than one leaking injectors or maybe the valves aren't seating properly. When was the last time the overhead was adjusted?

And of course there's probably the first thing Rawze would ask: When was the last time you did an EGR tuneup? Cleaned the system, replaced sensors.

As far as where to start? Start simple, start at the beginning (intake) and work your way back (exhaust). Post some more detailed information here and do an overhead adjustment and EGR tuneup, then start working your way back along the exhaust. Check the doser injector for leaks and/or soot buildup. Check the piping from the back of the turbo to the DOC for exhaust leaks or signs of wetness coming from the engine (coolant, oil). Next inspect the DOC and DPF faces. Take some pictures and post them here, also hop on quickserve and find the service bulletin that details DPF inspection. Using Insite perform a fuel system leak test. Even if you do find a leak it may have nothing to do with the exhaust smoke though.

At that point you should have either found the problem or gathered more information to help identify the problem. I will say that whenever I hear frequent regens coupled with unburnt fuel smoke from the exhaust pipe, my first thought is a DOC that isn't working properly, either due to reaching end of life or due to something impeding it's ability to properly oxidize the incoming fuel. But you can't jump to the end first.

[Therealarw]

(11-26-2023 )tree98 Wrote:  I would start by pulling the aftertreatment system apart and inspecting the DPF and DOC. The DPF is likely cracked if it's puffing smoke. You're either going to have to replace the DPF or at the very least get it baked and flow tested so either way it's gotta come off.

The DPF collects the smoke that the engine is producing, while you have the cans off, start the engine and see how much smoke the engine is actually producing. Might be a lot more than you thought.

Having a look at the face of the DPF can tell you a lot about the possible source of the smoke your seeing.Blue colored smoke is likely from burning oil, does it use quite a bit of oil ?Take pictures of the DPF face and post them here.

Has it been using coolant?

Will the engine pass a leakdown test using insite?? That's extremely important on these common rail engines.

Leaky injectors can cause severe damage, everything from heavy fuel impingement to catastrophic fuel pump failure.

Also don't use aftermarket injectors!! That's a huge mistake on an ISX, I know they are expensive from Cummins but trust me it's worth it in the long run.

How many miles are on this engine? The fuel pumps need rebuilt every 400K miles too by the way.

There's a list of things that will get you started.

My fault I should have included this also.. We had pulled the old motor out of it which was another ISX15 but it never had any issues as far as puffing white smoke out of the exhaust so I never really thought about pulling the exhaust apart or any of the aftertreatment. It's actually got a brand new fuel pump on it that's why I wanted to make sure to do the injector which was replaced with a genuine Cummins injector. I will talk to the driver tomorrow about it and see what kind of details I can get. The motor we put in it came out of a wrecked truck, it had been sitting for a little over a year

[Therealarw]

(11-26-2023 )JimT Wrote:  ... When was the last time the overhead was adjusted?

And of course there's probably the first thing Rawze would ask: When was the last time you did an EGR tuneup? Cleaned the system, replaced sensors.
...

Yeah so I had ran the rack on the engine prior to putting the motor in the truck, made sure everything was gone through. I actually have never done an EGR tune up but I did think about doing that. I was just curious on how easy is that to do? Is that something I could do or does it have to go through some special cleaning process? What about the EGR cooler? I haven't really dug too deep into the intake side too much but if this is stuff that should be done I'd just like to know if I'm able to service these parts myself. thank you guys!

[Rawze]

NOT doing a thorough EGR-tune-up on it every year = Noting but DPF and other emissions system problems. It is simple as that.
ref: http://rawze.com/forums/showthread.php?tid=7&pid=9#pid9


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and as far as the smoke is concerned...


Is it only when it starts going up a hill.. and it blasts all out real heavy for a bit, and then goes away?.
ie. (Doser injector needs cleaned/replacing. and/or .Not igniting the fuel properly during passive regen cycles).

or...

is it only when it first cranks up and then fades out as engine the warms up?.
ie. (Valve guide seal issues).

or...

is it all the time?.. somewhat light?... heavier when you get on it?.
ie. (Broken piston ring or excessive cylinder wear from sitting and rusting up internally. and/or. form oil starvation or abuse of some kind).

or ... something else?.