7.3 BAD blow by, rough idle, drinks oil

[Griffin]

I just bought a 00 F-350 with the 7.3, it has 161k miles on it. It has a Western Diesel pakage on it with 4" exhaust, ram air unit, 4 stage switch on the dash. It has the larger looking turbo on it and it looks new (not sure if it is stock replacement or what, I just know it is more than double the size of the turbo on my friends 99). It runs awsome above 2200 RPM, below that it runs rough like it has a miss in it, it is also very slow to start and if it is colder than about 65 outside, I have to plug it in, or it is nearly impossible to start. It also has alot of blow by on it, and I used it this weekend to pull a car and it ran great as far as power goes, but on a 800 mile trip it used 6 quarts of oil.

So to sum it up:

Hard to start
lower RPM miss or rough running
bad blow by
drinking oil like fuel
also has a strange knock sound at lower rpm


OK, now here is what I have done to fix it but none of it has worked,

new glow plug relay
all new glow plugs
checked the wire harness for the valve covers
replaced #8 injector (computer at Ford dealer flagged #8)

I am at a loss guys, I like the truck and want to fix it, but I don't want to keep throwing parts at it.

Thank You in advance for any help.

[Maintain]

Bad blow by - check all i/c boot's. A boost leak may also explain low power.

Your friend probably has an EARLY 99, which IS a smaller turbo.

Is your truck still drinking oil AFTER the #8 injector was replaced? If so, then you probably have other injector problems.

Notice any "cackle"?

Hope this helps...

[Maintain]

Originally Posted by Griffin

and I used it this weekend to pull a car and it ran great as far as power goes, but on a 800 mile trip it used 6 quarts of oil.

Nevermind about still using oil, I just re-read this...

[Griffin]

thanks for the quick reply!
I am not exaclty sure what they mean be cackle? But I did put the anti-cackle injector in #8 however it runs the same as it did before. It has lots of power above 2200 RPM just very rough at lower RPM.

[klpaul]

Faulty injector or injectors is very likely the issue. Over the years I have faulted and replaced injectors that have failed only to find other bad ones masked. I personall reccomend changing all injectors but many think this is overkill with such a hefty cost.

[Griffin]

Would more bad injectors be responsable for the massive oil consumption and the bad blow by?

[strokermann]

personally i believe this is a piston ring issue. a simple compression test is cheap if you do it yourself. but time consuming. i am a diesel tech in the navy and we start out cheap and simple. my first bossmann told me to remeber this simple phrase KISS= "KEEP IT SIMPLE SAILOR". if you are getting blow-by and burning oil like fuel and you can't start it at temp below 65. i serisouly believe that you have ring inssues.

"So to sum it up:

Hard to start
lower RPM miss or rough running
bad blow by
drinking oil like fuel
also has a strange knock sound at lower rpm"


these are all symptons of low compression. which leads me again belive its a ring issue. also what is teh color of your exhaust. i would hope buring 6q of oil it would be blue.
I would also take a look at the fuel pump and make sure it is correctly adjusted. that could lead to rough idleing and run great at higher rpms.

this is just my 2 cents, but i could also be wrong. hope this helps in teh future if this is wrong

[Griffin]

I was thinking it was probably a ring or piston issue as well, was just hopeing to be wrong. Thanks for the information and your services in the military.

[mschn99]

Short of a dusted motor....which would be piston rings....the only other real possibility i have for you is very bad injector o rings. Its probably unlikely where it always runs poorly...bit it would be worth a shot of replacing them.

[klpaul]

Strokerman sounds correct. I did not notice the lower end knock. Even so, yes if your injector O-ring is shot it will dump oil into your fuel. It will also cause a misfire type of knock. The volume of oil is very high however. Perform a contribution balance test and then do a compression test. Let us hope that you have one or more bad injectors but don't replace them without confirming good compression.