My 7.3 just started using oil. Took it in for an oil change and was told that there was no oil on the dipstick.
I had just checked it a few days ago and it was 1/2 quart down. When I take the filler cap off I can see smoke coming out in puffs as in maybe one cylinder is leaking. Kinda like an old Lionel train. My mechanic pulled the air cleaner and smoke was coming from there as well. There was oil in the intake hose going to the turbo. He checked the PCV valve and that was not plugged. The turbo is tight also. Whatever happened just did.
My mechanic says that probably there is a broken ring or a valve problem but there is no valve noise and the engine idles smoothly.
To further complicate the issue I just added 9 gallons of B100 biodiesel to top off the tank and have driven 290 miles since I did that. That would make it a B25 blend. It is possible that the biodiesel has cleaned the system enough to allow oil past the ring(s) but not too likely.
This truck has 186000 miles.
What are other possibilities that might cause a puffing oil filler neck???

 

not sure about the filler but oil in the intake tube is normal. Theres a ccv valve in the valve cover that vents into that tube and over time you get a buildup of oil. Some oil useage is normal on these trucks, especially one w/ 186k. Have your mechanic do a compresion test, that should tell you about the rings. If it's running smooth I doubt you have a weak cylinder.

 

A small amount of blowby can be considered normal. Puffing like a train is not. What color smoke do you have coming out the tail pipe? If you've got no external oil leaks, the turbo is in good shape, you're using a bunch of oil, and have excessive blowby, I'd say it's time for a rebuild.

How many miles do you have on the truck? Here's a link that has a video clip in it showing acceptable blowby with the CCV blocked off. https://www.ford-trucks.com/forums/6...ed-to-see.html

That should give you an idea of how bad yours is. If it's not bad, then you can check the bottom of the fuel filter bowl or the coolant reservoir for any signs of oil to see if you have an o-ring issue.

 

Sounds like you have excessive blow by. The bio wouldn't have done it. True, bio fuels will clean you fuel system, but since fuel and oil are seperate systems, it didn't cause your problems. Coolant level fine? No oil in coolant? Oil in exhaust? Any leaks on ground under truck when parked?

 

injector o-rings are a common failure item

 

Track your oil useage over time. Mine recently played "disappearing and reappearing oil game". Truck runs fine, nothing wrong with it, just for some reason the oil didn't want to show up on the dipstick even though there was plenty in the engine.

Just keep driving and maintaining it, and don't have your mechanic start tearing it apart just yet. There's probably nothing wrong. Check you oil on a regular basis. Remember these trucks will burn of a good quart of oil or more between oil changes, and that's perfectly normal. Blow-by is normal too, just a long as it's not a whole lot more than what's in the video link that Chris posted.

 

The best way I know of to monitor how my truck is doing is to keep track of mileage and oil usage.
So it was a surprise to discover that there was no oil on the dipstick when I took it in for an oil change.
There is a good chance that I have broken ring and it just happened.
I checked the blowby form the filler spout again today and there is more smoke coming from mine than in the video.
And, I can feel the pressure pumping when I hold my hand over the top of the filler spout.
It is most likely a single cylinder and it will probably run for some time b4 I have to do anything. But I'm not inclined to wait too long. I'm still monitoring the oil level and intend to drive it some more and then do a compression check.
Thanks for the response

 

60cents i seen your add for the truck in the classified and no way to get a hold of you just want to find out whats up and what your lookin for you can email me at jst4bigfun79@yahoo.com

 

I had this exact problem under warranty and got a new rear seal, and turbo (twice) from the dealer. I finally changed the glow plug O-rings and injector O-rings and that fixed the prob. 5 of 8 glow plug O-rings were obviously bad. They all live under the valve covers so blow-by these O-rings will pressure up the whole case, same as a broken ring.

 

Thanks Tim
I will remember that but I sold the truck