Newbie on Cummins here-

I am looking at a beautiful '03 6spd Quad cab 3500 dually w/ only 109k verified miles.

Looks like new in and out (corroborates low miles), and runs great, especially compared to my Powerstroke.

Only fly in the ointment is there is smoke in the engine compartment. A rather generous amount. NOT from engine degreasers or oil leaks on the exhaust manifold, but it smells EXACTLY like blow-by.

If I remove the oil filler cap, I get the same smoke, which I consider typical since every diesel I've ever owned has had some blow-by out of the valve cover. Putting my palm over the oil filler shows NO pressure in the valve cover, BTW.

I have asked around, and everyone says the Cummins has NO crankcase ventilation system where crankcase fumes are sucked into the intake and burned, but that the crankcase is openly vented to the atmosphere (w/ just a cup to catch any oil condensation).

They saw that Cummins rings seal so perfectly that there is no need for crankcase ventilation, and ZERO gets past the rings to make any fumes, so if you see ANY smoke when removing the oil filler cap, or from the breather the engine is SHOT.

I admit I know nothing about the Cummins, but I would be shocked that the EPA allowed open crankcase venting to the atmosphere in 2003, and I am hoping the problem is a detached breather line or something simple.

BTW, the engine idles so smoothly, you can't feel any vibration through the manual gear shift lever, and the engine has great power, with no visible smoke from the exhaust at all at idle.

Can anyone tell me how the crankcase is really vented on the model in question, and if even a little smoke is indicative of a trashed engine? I'd really love to buy this truck (super clean, leather interior like-new, etc.), but if the engine is shot at 109k miles, obviously I'll pass.

Thanks,
Bob

 

The engine is not shot more then likely, every motor has a small amount of blow by, It just depends how much

 

Yes, I AGREE about some blow-by being normal, but what concerns me is not the blow-by from the oil filler (valve cover), which seems to be what I'd expect in amount, but the noticeable cloud of smoke in the engine compartment at idle with the oil filler cap on.

Are there faulty hoses or anything that could cause this? I do not see or smell smoke from the engine compartment on the Cummins engined vehicles I see every day on the street.

Is the Cummins crankcase openly vented into the engine compartment w/ no removal of crankcase fumes into the intake?

Thanks,
Bob

 

First, all engines, including Cummins have blowby. This situation is not an indicator that your engine is worn out.

This fumes in the cab thing has been covered many times. Mainly back in '03 and '04 when the 3rd gens came out. There seems to be no absolute resolution to it, but one way is to route the blowby tube back to the rear of the truck with a long hose.

It seems to happen most when the heater fan is on and air is picked up from the cowl area and blown into the cab. Or maybe when the wind is just right and the fumes get blown to that area. It also has been suggested that some oils, like Rotella, have a stronger smell that contributes to it.

 

Thanks-So what you are saying is that there IS NO system on these trucks to draw crankcase fumes from the crankcase into the engine where they are burned?

With the hood open or closed, smoke IS VISIBLE at the front of the truck. Is this "typical" or would this fact scare YOU about this engine? I am not saying big clouds of smoke, but certainly visible smoke even w/ the hood closed.

I have no heartache with routing the smoke aft, but I am concerned because I have not noticed visible smoke from the engine compartment of other Dodge Cummins trucks. I just want to make sure I am not buying a lemmon!

OR that I'd be failed by the State Emissions Check for "visible smoke."

So we are down to guessing if this one is "excessive." This is an '03 model, so I guess SOME smoke is typical from what you say.

The question is then the difference between "SOME" and "TOO MUCH"?

Maybe I should have a Dodge dealership look at it? Or an independent Cummins tech?

BTW, I did a SEARCH but failed to turn up anything useful. Since you say it's been covered many times before, maybe you can suggest search terms or a way to find these threads? I want to research this as much as I can...

Thanks-

 

My '04 has no system to draw blowby into the engine. Just an open tube to vent the crankcase. Not sure how long that setup was used.

I never see any visible smoke in mine. But there are some fumes. At idle the amount is minimal, the fan is turning, and the engine is drawing in a lot of air, so I don't notice it. Running hard, it just blows away underneath.

When I say it was covered, I mean many complained about the smell of fumes in the cab while running the heater or sitting with doors open and stopped, etc. This was several years ago and seemed to just get dropped after while. There was talk about whether it was the oil or paint burning off the engine or what.

It seems visible smoke at the front of the engine is some kind of problem. I wonder if there is an oil leak at the valve cover and the oil is burning on the manifold, or one of the turbo oil lines are leaking or something like that? I would definitely track it down before getting the truck. Look at the blowby tube to see if smoke is pouring out of it. If not then where is it coming from?

 

Thanks-
I have finally determined that there is NO provision to process the crankcase fumes as you say, so I guess the EPA took it easy on diesel emmission controls until very recently (2007 I believe someone said).

I've also spent MANY hours on the Internet doing searches, and it appears there are LOTS of cases where low mileage (70,000-120,000mi) Cummins engines in the '03-'06 5.9 liter period spew smoke from their crankcase breather hoses, and in some cases, oil droplets out of the breather coating the entire underside of the truck.

The only reasonable explanation is worn, poorly sealing, or possibly broken piston rings according to several folks, and one Dodge Master Technician I got a hold of. This 3rd Generation seems to be the worst w/ regard to this problem of excessive BLOW-BY..

I cannot explain why reasonably-driven Cummins engines should be doing this, unless they had a run of bad rings that got into production.

I once had a Toyota Landcruiser that from 30,000mi would lay out a smokescreen that would have done a WWII Destroyer Escort protecting an Allied convoy proud. I finally gave up trying other stuff, and pulled the head and re-ringed it in place (engine block still in the vehicle). The compression rings were absolutely like NEW, but the bottom oil control rings were completely worn out, and had no tension against the cylinder bores (which showed zero wear). A new set of rings and I was back in business w/ zero smoke, and zero oil consumption. The Toyota just got a set of bad rings when assembled.

I also had a Ford Cortina (12,000mi when I bought it smoking) where the rings never seated properly, requiring me to do the SAME thing (hone the cylinder bores and install new rings), though in this case the rings weren't worn, they just never seated from the factory.

Maybe it's just as simple w/ this truck, though I doubt re-ringing a Cummins in-place is an "approved" repair method.

Bob

 

I don't see why you could not rering it in place, they are made to be rebuilt in frame, I bet number 6 is tough to get too.

 

could be a bad injector scared a cylinder or an injector is not working right

 

Yes, #6 would be a ***** because it's under the cowling so far.

On the INJECTOR, if an injector were leaking badly, wouldn't it cause the engine to run a bit rough especially at idle? This one idles so smoothly, you can put your tooth against the 6spd gear lever and not risk cracking it. SUPER smooth at all speeds and conditions.

I wish I had actual experience w/ these engines to know what's "doable" and what's not (or is too expensive to consider)

Bob

 

yea it will run ruff, mite be a head problem. just out of curiosity does it have a k&n air filter and you live in a sandy area

 

I haven't opened the air box to see what the P.O. put in there (the truck's at an independent dealership). It's a Dallas truck, but the atmosphere isn't particularly dirty here, and the truck seems way to clean to have been used on dirt roads (the interior looks and smells new and the frame rails look clean even where a pressure washer would be tough to reach).

When I see it next time, I'll check the filter. Good point!

Bob

 

Bob,

It seems you have not determined where the smoke is coming from. You can't say the engine needs new rings just because you see smoke. If there is smoke in the engine bay and the filler cap is on, where is it coming from? The blowby tube or somewhere else? Don't jump to conclusions about the rings. Or that you can fix it with a quick ring job.

Even if it is from the blowby tube and not an oil leak, it could be piston damage from overheating, high EGT at some point, or from the use of ether. There could even be cylinder scoring. Who knows.

Since it runs fine you might look at some similar trucks to see what normal is. Or break down and do a compression check. The only thing that seems like a definite problem is the "cloud of smoke" you mentioned.

 

I would remove the rubber boot on the floor shifter, there should be another boot under this one. It is either torn or wasn't mounted to the floor properly. You will hear more trans noise if leaking or torn. Also check the seal under the hood by the cowl. Fresh air vent is located there and if you have any exhaust leaks or valve covers leaking it will allow fumes into cab. Fumes will come out vent, oil is captured and drained back into oil pan. Some diesel oils may smell you can try oil additive, Mopar "Diesel Fresh", P/N - 05139947AA.
1 - BREATHER COVER BOLT
2 - BREATHER COVER
3 - BREATHER TUBE
4 - ROCKER COVER
5 - BREATHER TUBE MOUNTING BRACKET
6 - LUBE OIL DRAIN TUBE
7 - O-RING
8 - BREATHER
9- BREATHER MOUNTING BOLT

1 - INSTRUMENT PANEL
2 - FLOOR CONSOLE
3 - BOLTS (3)
4 - SHIFTER LEVER

 

Bob