Maybe my understanding of the injectors is not right, and my hypothesis is off. I don't know what else it could be though.

 

I would guess your injectors are worn too. I'm not sure about the compression test. Did you pull the idm relay when you did it? Did you pull all the glow plugs and test one at a time? Having open cylinders makes it easier to spin over and cant get compression from the adjacent cylinders. Usually a bad head gasket but very unlikely on the 7.3.

 

Did you pull the idm relay when you did it?

I'm assuming this is so the injectors don't try to fire? I did not have the valve cover harness connected when I did it, so this would essentially do the same thing correct?

 

Have you checked the turbo?

 

I did not pull the IDM relay when doing the compression test. What would that do?
I DID pull all 8 glow plugs so it could spin freely.
Turbo and pedastal was replaced a couple thousand miles ago as part of trying to fix this. Downpipe is dry.

 

It keeps the injectors form firing and pumping fuel into the cylinders. It could skew the numbers.

 

Oh then yes. Same thing.

How many miles do you have on the injectors.

 

I'm not sure, that's the thing. I'm taking care of this truck for a friend overseas, and he bought it with reman engine that only has about 80k miles on it. But I don't think the injectors were changed because there is nothing about it on the receipt.
The truck has 280k miles or so.

At least 1 of the injectors has been replaced (not the suspicious cylinder) because it's got a brown top instead of the gold-ish color.

 

Well, I presented this situation to a guy I know who works at a diesel shop that does powerstrokes, and apparently all the guys there think that the 420 cylinder is the only good one, and the rest are burning the 3qts/fuel tank.

Does everyone else burn this much oil who has this compression?!?

 

I have a hard time believing that 7 out of 8 cylinders are just plumb worn out and dump 3qts into your cylinders. Especially with 80k on a stock engine

 

But in Michigan like Massachusetts the trucks rot out before the engine is junk so you could probably find a junk yard 7.3 for about $500 or craigslist parts truck.

 

I've been told that a good OBS 7.3 engine should net at least between 380-400 psi, and that anything below about 375 or so indicates a tired engine. Of course, there are several ways to check compression, so it depends.

Bad compression from worn rings and cylinder walls and/or valves can cause oil burning.

The quality of remanufactured engines can vary widely.

 

Ok, so they're probably a bit lower compression than they should be.

What kind of boggles me is why don't I have a bunch of blowby if 7 cylinders are bad enough to use that much oil?
To me (and it's very possible I just don't there to be an issue with the cylinders) it just doesn't add up.

I think I may try replacing the 420 cylinder injector.

 

Update of sorts. Finally got the oil changed and some archoil added to the oil.

1. Opened the fuel bowl to change the filter and found out it was a Wix cap and filter unit so I put it back in to wait until I get something besides my Motorcraft filter. The fuel in the bowl wasn't exactly clean green. Not dark but advice is needed (see pic)

2. Runs smoother with EBP tube cleaned! However! Still very low on power, like no difference between 1/4 throttle and full throttle. Unplugged the ebp sensor: no change except for a little rougher idle.
Replugged in ebp sensor and unplugged newly installed MAP sensor: CEL comes on and plenty of power, how it should be. Replugged MAP sensor in and CEL goes away and back to no power still smooth. Advice please there also!

 

Hopefully this picture is clearer. I hope not O-rings. But could be?

 

What did the side of the filter look like? If it was black/brown then I'd look into injector O-rings. As far as the map sensor, you could check to see if the sensor is bad by replacing it, or you might have boost issues, turbo worn? Compressor side dusted? Pop off the air duct and check the turbo for play. The stock filters are known to be insufficient and full of leak points in the stock filter housing.

 

Would be nice to put a boost gauge on it. I’d get a new map sensor too. Maybe I missed it but this truck throws no codes and has no visible oil drips or leaks? When my ccv gets a kink in it, the truck will puff blue smoke. Maybe your ccv filter is clogged. If unplugging your map gives it power then it’s defaulting to the preprogrammed fueling tables. Wouldn’t this imply that the injectors can perform properly when given the correct load calculation?

 

I agree, this truck CAN perform properly, but something is telling it to defuel. Seems electrical/sensor related vs mechanical/physical issue.

CCV doghouse is clear, hose isn't kinked, just verified all that.

A question I have: WHERE does the vacuum/boost hose from the MAP sensor go TO?

 

The filter was dark in some areas. It's yellow to start with so I'm not sure if it was just dirty or also oil stain.

The lower power issue is not a turbo issue.
Plenty of power with MAP sensor unplugged. Plug it in, low power, still runs smooth.
Feels like the torque of my Civic. Again, no issues with the turbo.

 

I would blow air through the map line and make sure it’s not plugged. As for the oil. I have not idea. You said you already replace the orings. What brand did you use.

 

You can use a paper clip to jump the test ports under the hood. Then count the flashes of the cel light. Vacuum line for mine originally came off a nipple on the pass side plenum. Right about center shooting outward towards the fender.

 

Vacuum line for mine originally came off a nipple on the pass side plenum. Right about center shooting outward towards the fender.

This may be my problem. My line goes something just above the left inner fender that the main vacuum pump line goes to. We'll get that fixed.

 

Making power should take a back seat to the oil consumption. I’m fairly new to the diesel world but from what I understand, you would only be able to lose that much oil trough the turbo due to a bad seal on the exhaust side, or an injector oring. That assumes you don’t have a massive external leak when driving. I’m not certain on the mechanics of what would make an injector lose as much oil as you are. I could see a turbo seal causing it but since you see and smell oil burning, It’s time to remove the injectors and perhaps rebuild the turbo.

 

The owner of this truck (before he moved overseas a couple years ago) replaced the turbo and pedastal and o rings trying to chase the burning oil. As I understand it changed nothing. I actually helped change with the O-rings. As to what brand I'm not sure, but he got them from Xtremediesel I think.

There is an oil leak on the exhaust manifolds I can smell while driving, but no drips when i shut it off. Visual check confirms some oil on exhaust manifolds at the very rear of both. Not much though.

 

So the valve covers are both leaking? I don’t mean the turbo pedestal o rings, I mean the internal seal of the turbo itself.

 

Not sure if they are. I just had them off and I tightened properly, we'll see now.
Yes new turbo: compressor side, center, exhaust side. entire unit was replaced. So unless the new turbo is faulty, I dont think it's that.

Fixed issue #2 with low power! Found the MAP sensor had a vac line going to it which was supposed to go to the HVAC box (not sure exactly what it is) which I point to in the picture.

 

Once the turbo starts to leak, and I may be wrong, but the center section must be replaced.

 

It’s possible the valve seals are the cause of your oil consumption however 3 qt per tank is a lot to go by the valves.

 

I was wondering this as well. But the valve seals seem pretty "raised" in the head and unless under the valve cover fills up with oil when it's running, I don't know how it would get past them.
But it does have symptoms similar to it. Like blue smoke on startup, then leaving a stop after an idle.

 

Ok, given the past few posts, I found something today that was interesting and possibly related.

I checked the oil today and also looked for any oil leaking on the exhaust manifolds. No more near the rear as I mentioned above. I only saw oil running down (trace of a long drip and not alot) the passenger side, directly/behind the dipstick tube area. At first I thought it was VC gaskets, but I had torqued them with a torque wrench when I had the VCs off and upon closer inspection with mirror and flashlight, all around where the exhaust manifold attaches to the head is damp. So it's leaking out at the exhaust flange.

THIS is also the same cylinder that had a higher compression (cylinder 5).

So what would cause that? Nothing from the turbo would get BACK to that point as it'd be against the flow of exhaust.
So it's either from inside the cylinder or from the valve. Could be valve seal and guide?

Again, compression was up at 420 and tested multiple times so I don't think it's a ring issue.

 

I personally dont think your compression is that bad. The 420 one stands out so thats where I would focus on first. I have had less compression on one of my 7.3's and it used no oil. I would focus on that 420 cylinder because if you are dumping oil the compression is going to go way up. You could try switching one of the injectors with that one and see if there is a change. Check your push rods on that cylinder and see if they are bent. Hope you figure it out.

 

Bad oil control rings?

 

So the truck was idling a little rough today (it had stopped running slightly rough like this after I changed the oil, but after a couple hundred miles, it back to it after it's warmed up).

Just checked the oil, and it's still using oil. I've driven about 250 miles and it's about a quart down.

I noticed this weird random smoke when I got to work this morning, so I decided to take a video after I observed it again this afternoon.
Keep in mind, there is noone in the cab, it's just idling on it's own, it's fairly smooth, but definitely could idle smoother. The smoke is definitely blue coming out of the exhaust. Has anyone seen anything like this?

Sometimes it's more frequent, sometimes not.

When I take off from a stop light, it's a continuous blue smoke of the amount in the video for about 5 seconds or so.

I haven't done anything about it yet, still trying to observe in order to fix the correct thing.

Thanks for your advice!