I have a 2002 F350 7.3L w/superchips programmer, k+n cold air intake.
Does NOT smoke a lot from tailpipe
Not running rough since I changed my oil to rotella 5w-40w synthetic.
Appears to have good amount of blow by coming from the oil fill when engine is warm.

Can Bad Injector O Ring(s) cause blow by and oil consumption?

 

There has been several post about blow by this month and it comes down to most were not as bad as seen.You can remove the fill cap and turn it upside down on the fill tube while the motor is running.If it vibrates off that is good.If it immediatly blows off that could be bad.
Serious blow by and oil consumption would mean bad/worn pistol rings.

 

Truck has 154,000 miles. I had lukes oil stabilizer in it (about a gallon).
Truck ran horrible, exhaust smelled, and hard start on warm/cold days.
I am assuming this was because I had to much lukes in it.

I Flushed the system, changed the oil filter, oil to rotella 5w-40w synthetic.

Started it up today with 70f temperature outside with no issues. Matter of fact, from a cold start it literally took a couple of minutes to warm up and ran great.

I put lukes in it hoping to reduce the blow by/oil consumption. I took a 200 mile trip a couple of weeks ago and found I was 2 quarts low in oil. No oil leaks, I am hoping It did not burn the oil.

Oil Fill Cap does not blow off, but there does appear to be a very light puff in the blow by when the engine is running.

 

Check your fuel bowl for oil could explain whereits going and why the exaust smells!

 

So in other words it can cause oil consumption but not blowby.

 

Yesterday I had the fuel filter changed (the one at top of engine). It did look dirty and black. Could that be a sign of bad injector o-ring(s)? (blackish fuel filter)

 

Yes that sounds like a good possibility!

 

If you've been running it since you changed the fuel filter you could pull the filter out and check it again. If there's oil in there it would be black again already. I've never experienced this so I'm just kinda going by what I've learned on here!

 

If I decide to do a compression check, would a bad injector o-ring give me a false positive of premature ring wear?

 

No. I think. Anyone else have any input on this. By the way why do you think you have blow by. Have you done the blowby test? Take your oil fill cap off and place it upside down on your oil fill tube with your truck
Running and see if it wants to blow it off the tube. If it just rattles off from the vibration of the motor that's ok but if it is actualy forced off that would indicate a wear issue with the piston or rings.

 

If the injector is properly seated (the hold down bolts at 120 in/lbs) the copper washer between the bottom of the injector seals the hole in the injector cup and the top of the head where the injector nozzle reaches into the combustion chamber so a bad injector o-ring will not give a false compression reading.

The top injector o-ring is to keep the HPO from leaking from the top of the injector bore and the second o-ring to keep the HPO from leaking into the fuel side of the injector. The third oring seals the injector in the injector cup keeping the fuel contained between the second and third o-ring. If the second o-ring leaks then the HPO will get in the fuel and be injected, along with fuel, into the combustion chamber which causes high oil consumptio. The reason fuel will no get into the oil side of the injector is due to the fact that the HPO pressure is subtantionally higher then the fuel pressure.

 

Robin, I'm really hoping your theory is why my oil consumption is so high. Next GTG at my house I'll swap them out and see what the results are.

 

If your compression is good this just may be what's happening. When you put your foot into it there's easily 2400+ PSI of oil pressure against the top and middle o-ring. Lots of oil can pass by a bad top or middle o-ring and it could lower your peak HPO pressure depending on the size of the leak or number of bad o-rings.

 

Ok, bad injector o-rings .... with oil consumption, is more than likely the problem before ring wear on truck with 154,000 miles?

Is there anything I need to be aware of if trying to replace the o-rings myself? (special tools)

Also, do you happen to know what fitting I would need for compression test (7.3L) and what is the correct reading?

 

I can not answer your question or whats going on, however, i've done some extensive reading, for the last 6 months, to know, that you should not be adding anything to your oil...