I have another thread running on my recently rebuilt engine that is burning oil.

2003 Ram 3500 dually. 6spd manual. 119,000 total miles since nes. 9000mi since rebuild.
No Cat, no muffler (just a straight pipe where muffler used to be).

I just spoke to the rebuilder, and they say they say it's probably due to over-fueling.

Question: What are external symptoms of over fueling?

1) The engine is now using 1 qt per 650mi after 9000mi (started at 1qt per 80mi after rebuild, then went to 400mi per quart, but after 6000mi has stabilized at 650mi per quart).

2) Before rebuild the engine was not "using" oil (but had blow-by in cyls 1 and 6 due to scoring). No oil smell to the blow-by. It smelled like diesel exhaust.

3) The engine idles and runs perfectly, gets 23mpg around town, and 28mpg on long trips if I average 55-62mph.

4) I had the injectors pressure, pattern, and flow tested by an injector specialty shop to 27,000psi while the engine was being rebuilt, and they told me the injectors were absolutely like new in all respects. I asked about repairs or injector rebuild, and they said it would be a waste of good money.

I installed an Air Dog w/ a 2 micron filter to make sure no water/dirty fuel would get to the engine. Did this while the engine was out as well.

5) The new engine has NO blow-by whatsoever I can detect.

6) There is some blue smoke on start-up and until the engine warms up, and the last inch of the tailpipe looks damp. The fender gets pretty sooty within a few hundred miles after washing it. I can't smoke going-down-the-road.

Does that sound like over-fueling to anyone, or can you even tell by the way an engine uses fuel and runs at all?

The shop that did the engine said they will look at it, but if they tear the engine down and they suspect over fueling, I will have to pay for another rebuild out-of-pocket, so I want to be DAMNED sure if I can that it's not my fault before they get into it.

Thanks, guys,
Bob

 

Why do they suspect it is over fueling? What is their definition of over fueling?

Over fueling is just that, using more fuel than needed and you will see black smoke out the tail pipe.
The symptoms you describe sound like there are issues with piston ring to cylinder wall clearance. You should not be using ANY oil.

 

Blue smoke at idle sounds like possible injector issue. Any performance chips or the such?

 

Blue smoke only lasts a couple/three minutes. No smoke when warm or hot.

Engine runs smooth as silk cold/warm/hot. I've driven Cummins w/ one or two bad injectors and you can FEEL the uneven power from each cylinder.

No performance chip.

So over-fueling can happen even if you're getting 23+ MPG?

I would have thought it would have to run rich and get crappy fuel economy to over fuel. Not so I guess?

Bob

 

That's how I see it, too, but I have to be educated and ready if they try to blame it on something else as they are already talking about.

He also suspects a major external leak, but the engine/tranny are bone dry. Hasn't leaked a drop onto the garage floor in 9 months. He says it can leak where you can't see it, but you can't fool gravity forever, and a leak WILL show.

If I am knowledgeable, less chance they will try to mess with me I figure.

Bob

 

take your map sensor out and have it cleaned.. if it reads preassure incorrect it will cause excess smoke in the exhaust because it thinks there is more boost then really is.. so it adds extra fuel to compensate for the boost.. but if there isnt enough air to equal that extra fuel.. then you just blow black smoke out the tail.. you will get really good mpg if this is the issue aswell because it overrides the emission injection with an injector variance injection... kinda what a chip does.. it overrides the emission injection and uses this phase in the injection to make a little extra power that adds mpg...

 

Wow; that's a new one. I would have never guessed that extra fuel gives better fuel economy.

So it's possible to over fuel while actually going farther on that gallon of fuel than if you were NOT over fueling!

Less fuel flow=worse fuel economy?
More fuel flow=better fuel economy?

Counter-intuitive for sure!

I'll try it.

I hate to mess up my mileage but if it's damaging my engine, that's bad.
I've never used more than about 1/3rd throttle. Perhaps that's a good thing, then.

Bob

 

the engines come from the factory with 3 injection cycles...
1st is preinjection
2nd is power injection
3rd is emission injection

the 3rd injection is so late that it is always used for heat instead of power... so its wasted fuel when there is no smoke out the exhaust... what happens is when you add a programmer in the loop it moves the timing of the 3rd injection to make it more power injection and then add extra fuel to make more exhaust heat to spool the turbo up faster...

there is a safety injection cycle that is called variance injection cycle for when your building boost.. but if the map reads low then it will never think its out of this cycle.

 

The 03 and 04 truck only have two injection events.

If you really want to know for sure, you will need to do a compression check. There are tools available for this online. It is very easy to tell right away if you have a bad cylinder or not. Usually over fueling will cause black smoke and you will possibly be making oil. If the exhaust pipe is wet it is a compression issue for sure.

Hope this helps,

Ben

 

I do not think you have a fuel problem with the milage you are getting.

Blue smoke is usually oil burning. Was the head rebuilt? Were the valve seals replaced? Worn valve seals will allow oil to enter the engine when not running and cause smoke just after startup. Not sure if this is your problem but could be part of your oil consumption.

Turbo seals could also be leaking. Oil will be present in the intake before the engine if a seal is leaking.

 

Not necessarily does the both seals go out on the turbo. I've seen the hot side leak if the turbo was fueled hard.