6.9 IDI Burning Oil Excessively

[PossumF250]

My 6.9 IDI burns almost a quart of oil to a tank of fuel, and all (or most) of that oil seems to be getting sucked through the CDR valve. When I realized the inside of the intake manifold was coated in oil, I replaced the CDR valve, but the problem continued. I thought the oil might be overfilled because when I changed the oil, I found it took almost 12 quarts to read full on the dipstick (when checked warm, not cold) instead of 10. This is with the Motorcraft IDI oil filter, not the bigger Powerstroke filter. However, I let it run "low" a couple times to what should have been around 10 quarts, and, based on the gray smoke that continued to come out the exhaust, it did not stop burning oil.

Does anyone have any ideas as to why it is sucking oil through the CDR valve, and why the owner's manual-specified 10 quarts barely shows up on the dipstick?

 

[IDIBRONCO]

Are you sure that it's all being sucked through the CDR? This rarely happens although the CDR gets blamed for it a lot of times.
I can't even begin to offer a guess as to how/why this happened. I've run across two oil pans that took an extra two quarts of oil in order to fill a new engine. At a glance, they didn't look any different than the others did. I only knew it when those engines need the extra two quarts.
There is one other possibility that I can think of. I can't remember which is which for sure, but one type of dipstick is longer than the other one is. I think that the Later ones are longer. These are the ones that have a bracket that runs over the top of the valve cover. If you have a short dipstick in a long tube, this could explain the extra two quarts of oil too.

 

[PossumF250]

I'm not sure all that oil is being sucked through the CDR. All I know for sure is that when I remove the air cleaner and the CDR valve, I see a significant amount of oil inside the intake manifold and CDR.

Maybe there's another issue contributing to the oil burning? Valve seals? Piston rings crossed my mind too, but with the oil fill cap off while the engine's running, there's no noticeable blow-by, so I'm thinking that's unlikely.

I've run across two oil pans that took an extra two quarts of oil in order to fill a new engine. At a glance, they didn't look any different than the others did. I only knew it when those engines need the extra two quarts.

I wondered if the oil pan could possibly be larger, so thank you for confirming that larger oil pans do exist. The engine is a junkyard replacement of unknown age and mileage, so anything is possible with regard to the dipstick, tube, and oil pan.

 

[rhythim]

I'm kinda there with you on my '85. Has either 122k or 222k on it, but given how good the interior is I lean toward 122k. It drinks about a quart every 500 miles or so. Virtually no smoke out the tailpipe unless my foot is in it, no out of the ordinary oil in the intake, no blowby to speak of, and it isn't putting any on the shop floor while it's parked. Haven't checked compression, but like you I don't think that's a problem due to lack of blowby.

I've never had an engine that used oil that I couldn't figure out why until this one, and it bugs the crap out of me.


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[Farmer Rock]

What brand of oil are you guys using?I had this happen to me with shell rotella,and it seems to be a known thing that these trucks burn shell rotella oil like gasoline in a big block truck.It drove me crazy for a while,since it was just all of a sudden and it went through more oil then fuel.




Rock

 

[PossumF250]

I'm kinda there with you on my '85. Has either 122k or 222k on it, but given how good the interior is I lean toward 122k. It drinks about a quart every 500 miles or so. Virtually no smoke out the tailpipe unless my foot is in it, no out of the ordinary oil in the intake, no blowby to speak of, and it isn't putting any on the shop floor while it's parked.
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Minus the lack of oil in the intake, that's exactly how mine is too. I forgot to mention that earlier, but the exhaust smoke is really only there when my foot's in it or I'm driving on the interstate (so my foot's in it constantly).

 

[PossumF250]

What brand of oil are you guys using?I had this happen to me with shell rotella,and it seems to be a known thing that these trucks burn shell rotella oil like gasoline in a big block truck.It drove me crazy for a while,since it was just all of a sudden and it went through more oil then fuel.




Rock

I'm using Delo 15w40. I went with Delo because I'd heard these trucks love to burn Rotella like you're talking about.

Also, I don't know what was in the truck when I bought it, but I've only used Delo since buying it, so I have nothing to compare to in terms of how much oil it burns when using different brands. Could it be worth switching to see if something else works better?

 

[quickster]

Minus the lack of oil in the intake, that's exactly how mine is too. I forgot to mention that earlier, but the exhaust smoke is really only there when my foot's in it or I'm driving on the interstate (so my foot's in it constantly).

That's what was happening to me. Smoke only when I got on it. My heads are in the process of being rebuilt now. Valve recession.

 

[Kevin 007]

Yea they will burn the engine oil as if it's fuel, and to a certain extent; won't show any blue smoke or any other evidence of oil consumption, aside from the consumption itself.
I have a couple that are doing the same thing and have seen a handful that have huge oil consumption problems also. Not a CDR problem in my cases. I suspect perhaps either a few broken oil rings, possibly from previous improper use of ether by previous owners etc. I wish I had time to tear down of few of the oil hungry engines to see what is going on

 

[david85]

What kind of driving cycle? Mostly highway? What RPM are you at?

Mine burned that much fairly consistently. 1L per fillup, and yes it was rotella. I tried replacing the CDR but didn't make much difference. Rebuilding the engine with new valve stem guides and seals sure did the trick though. All cylinders had >400PSI compression before the overhaul so I suspect valve stem seals were the real culprit. As these engines age, they can slurp oil down for years and still run fine.

I'm not saying to rebuild it or overhaul the heads, but if the CDR treatments don't work, you could try replacing the valve stem seals. It can be done in frame. Just be careful to keep the cylinder your working on at TDC to prevent dropping the valve by accident.

 

[Black dawg]

When you change the oil, remark the dipstick for 10 quarts and see if the consumption continues. Wouldnt be surprised if it does, I have had many 6.9s that would use a quart per tank. A local here has an 85 that he bought with 50k on it in 1990, has always burned a quart at 500 miles........I have NEVER had a 6.9 that burned less than that......with original ring gap specs and valve seals.

 

[Kevin 007]

A note with the 6.9's and their valve seal design that allow more oil to pass. (And by more oil, it's not lots. With seals in good shape, the might use just a quart or so more then a 7.3 will go thru, over the course of an oil change). They do tend to have less valve guide wear, catastrophic valve guide failures and the classic "chuff-chuff" sound that many idi's make due to a worn valve guide , compared to 7.3 idi's with the tighter valve seals.

There also is the difference in rocker design, but that is less likely to have an impact on guide wear, in my opinion and observation.

I do believe the 6.9 style valve seal is a better choice then the 7.3 seal, to allow for some lubrication of the guides which are a known wear point.

 

[PossumF250]

What kind of driving cycle? Mostly highway? What RPM are you at?

Mine burned that much fairly consistently. 1L per fillup, and yes it was rotella. I tried replacing the CDR but didn't make much difference. Rebuilding the engine with new valve stem guides and seals sure did the trick though. All cylinders had >400PSI compression before the overhaul so I suspect valve stem seals were the real culprit. As these engines age, they can slurp oil down for years and still run fine.

I'm not saying to rebuild it or overhaul the heads, but if the CDR treatments don't work, you could try replacing the valve stem seals. It can be done in frame. Just be careful to keep the cylinder your working on at TDC to prevent dropping the valve by accident.

I'm currently driving it to and from work, 45 miles both ways, 5 days a week. It's a mix of highway, city, and backroads driving, but mostly highway at 60 mph, so maybe 3,000-ish rpm (no tachometer).

I wasn't overly concerned about the oil consumption, but I thought if there was an easy fix, it'd be nice not to have to top it off so often and save some money on oil. Sounds like it's not out of the ordinary, so I'll probably just keep driving it as is for a while.

 

[PossumF250]

When you change the oil, remark the dipstick for 10 quarts and see if the consumption continues. Wouldnt be surprised if it does, I have had many 6.9s that would use a quart per tank. A local here has an 85 that he bought with 50k on it in 1990, has always burned a quart at 500 miles........I have NEVER had a 6.9 that burned less than that......with original ring gap specs and valve seals.

I will do that! Even if the oil consumption continues at 10 quarts, it'll be nice to know how much oil is actually in it when it inevitably drops below full.

 

[PossumF250]

A note with the 6.9's and their valve seal design that allow more oil to pass. (And by more oil, it's not lots. With seals in good shape, the might use just a quart or so more then a 7.3 will go thru, over the course of an oil change).

I think it's funny that an extra quart between oil changes is considered not a lot, but then they aren't called oil burners for nothing! And of course, here I am adding sometimes almost two quarts in a week.