Just my opinion. I am not "Officially" a diesel mechanical. I'm a diesel enthusiast. Primarily the 7.3L. But I've worked on various aircraft, grew up working everything that broke, and do all my own service and maintenance one everything I own. Oh, Early years I was into early Ford Mustangs. In my middle years I was into Jeeps and mud riding and rock crawling. Depending on what coast I was on. And in last probably 22 years or so have got into having fun modifying 7.3L PSDs. That's my disclaimer. This is only my observation of this discussion. And my opinion. I spent time on this actually because I still can't learn enough. I hope to learn more from this. That is why I read a lot of forums. I'm a lurker. I read a lot. But do not post often. So...
Best advice I can give now is take the turbo off then the exhaust manifold..
Agree, I would start by pulling the turbo. But would not pull the exhaust manifolds until I digged a little deeper tand did further testing o hopefully find more evidence to narrow down potential issue. As, R&R the exhaust manifolds in the truck is a real PIA.
Pull the turbo. Inspect where the Up-Pipes come together at he turbo, baby's butt. It should have dry black exhaust residual on the inside. Like in picture attached.
Failed Turbo Shaft O-Ring
Down Pipe - Up-Pipe Exhaust Inlet at turbo
However, if the exhaust side of turbo at the down pipe is wet and oily, and the turbo exhaust exit side has obvious oil in it. You most likely have a failed Turbo Shaft O-Ring
However, if the exhaust side of turbo at the down pipe is wet and oily, and the turbo exhaust exit side has obvious oil in it. You most likely have a failed Turbo Shaft O-Ring
Turbo Exhaust Side of Turbo
If oil is found at the exhaust collector, baby's butt, inspect the down pipe side at the turbo as techmech mentioned above. If it is sure enough a turbo shaft seal failure you will know. There will be oil residual where the downpipe connects to the turbo. And oil at the exhaust pipe joints under the truck. See attached below.
So, if it was me, after pulling the turbo and you found oil in
"Both" of the exhaust outlet and the exhaust inlet, I would start by removing the up-pipes first. Inspect the up pipes to see if the same oily substance is found on the driver's side or passenger side pipe. Or both.
Make sure there is no oil getting into the intake manifold. If the exhaus on the 7t side of the turbo is wet but the cylinders are dry then yes it probably is the turbo. The intake manifold gasket does seal on the crankcase side as well but under boost pressure you would have lots of blowby if they would be leaking. Those gaskets are typically very good.
I not sure I follow or understand point above. It's known that the 7.3L PSD will build some up oil residue, not excessive, at both the intercooler and turbo CAC boots. Which will at times, you may already experienced this, blow the CAC boots off the intercooler at higher boost pressure. It is normal for oil to collect at the lower CAC boots and in the bottom of the intercooler. Which will over time lead to, usually only a slight amount, of oil at in the Y-pipe at the turbo and intake connection. This is normal. And does not cause the issues you describe. But if you have sure enough a lot of visible oil, like liquid form, you have other issues.
The reason this oil collects here, IMOP, is the 7.3L, and all other diesels, have all the the internal parts designed to extremely tight specifications.
AT...operating temperature. That's why heavy equipment, OTR trucks, evern jet engines, warm the engines up to operarting temperture after starting and before they put a load on the engine. When these engines are cold the bearings, rods, piston and rings are loose and have gaps at the respective mating surfaces. And as they heat up they expand and the gaps will tighten, seal, and meet up together to the specifications the engineers designed into the engine. All this to say, the oil found in the CAC and intercooler etc. is primarily coming from a slight amount of oil blow by at start up. And is magnified when they are cranked and go and engine is loaded up before it has has a chance to reach operating temperature. Also curious, albeit not important, but pretty sure the intake manifolds are mounted to the heads. Not the crankcase. And yes the adhesive sealant ford useup s is pretty stout. You pretty much have to chisel the intake manifolds loose to remove from the heads.
That said, and why this lengthy response, is I'm trying to get my brain wrapped around a damaged / defective the oil ring. The oil rings function is to insure/maintain the proper amount of oil / lubrication on the cylinder walls. With exceptional machine work of trueing and boring the cylinders. And with perfect gapped and installation of all rings, and the engine warmed up to operating temperature, the oil ring is only going pass the amount of oil it was engineered for to apply to the cylinder walls. I can't think of or recall where the oil ring on the piston was upgraded to increase the performance of oil application to the cylinder. Not to say there are not applications where this is down. Just not anything I'm familiar with. So a damaged oil ring to me would not add or pass more oil on the cylinder walls. It would pass less. However, it probably could at some point damage the cylinder walls to the point the compression rings can no longer seal and hold the pressure on the power stroke. But that is a different issue to address.
Thus, in my simple mind, a defective or improperly installed piston oil ring wouldn't exceed or apply more oil than a good properly installed oil ring. A defective / broken oil ring would not properly maintain the oil in a consistent uniform coating on the cylinder walls. Thus wouldn't pass more oil. But, there would eventually be other issues at some point. And if the
compression rings are installed correctly to spec they should prevent any oil blow initially. The "power stoke" applies considerably more pressure on the piston and compression rings to make power than the pressures fluctuating inside the block.
So my thought is, if in fact, perhaps an improperly installed oil ring, or one that was damaged during installation, then this oil ring could potentially could score and damage a cylinder wall pretty quick. Which could lead to some blow by in a cylinder Due to compression rings would not seal correctly if the cylinder is damaged. So, if that is the case, this is not a repair that you could properly fix by removing the exhaust manifolds. And R&R rings on one, or more, pistons. The engine would have to be removed to have the engine cylinder repaired properly.
So, what I would do, or did, before I started tearing down the engine. I would look further to verify if in fact it is a piston oil ring issue or something else. Because it may determine if it is an in the truck repair. Or if you may have to pull the engine to repair the block.
Here are a few things you can do to see if you can determine which, cylinder or cylinders, and the potential cause:
- If you don't have a scope instrument to inspect the cylinders see if you can find a loaner somewhere. to inspect the cylinders. Pull the valve covers and the glow plugs. Rotate crank until each cylinder is bottom dead center and run the scope down the glow plug hole and inspect the cylinder walls for scoring and for sign of oil residual or burning on piston tops. They should all look similar as nice and clean and shining if engine well maintained. If one or two cylinders are different than the others they may be suspect.
- I would do a compression check on all cylinders. They all should have pretty much the same compression. At least within 10% of each other.
- If nothing was found after those checks I would go ahead and do a cylinder leak down test. Maybe even do it first. Again if one or two of the cylinders do not maintain the same pressures as the others they may be suspect.
All this to say, in my opinion, if a defective oil ring is the cause, re-ringing one, or more, pistons is not going to fix the issue. If happens to be a damaged oil ring. The issue is going to be damage to a cylinder wall. Thus, you will not be able to do an in frame repair. Because engine will have to be pulled to properly repair.
Just my thoughts. But I would start at the turbo first. And then checking the cylinders. Pulling those exhaust manifolds while in the truck will be a tough PIA job. Just to find out you have to pull the engine anyway due to a damaged cylinder.
Blue
