Oil in air intake - Banks turbo

[Frank M. Hardcastle II]

I have oil in my air intake on top of my motor. The only place it could come from is the turbo. Mechanic yesterday replaced AC11 glow plugs with AC60 and replaced the glow plug controller and glow plug switch/sensor. I had it run to a switch on the dash just after I bought it 2 years ago because it came on all the time even during the heat of the summer after the engine had been running for an hour or so. Finally, The dash light quit coming on 2 days ago and the truck wouldn't start unless I plugged in the block heater to an extension cord. Figured it had finally given up. Well the mechanic told me I had cut the wire with the emergency brake somehow and he fixed it. Well I had already bought the above parts and figured some if not all needed to be replaced anyway due to the previous problem with my hyperactive glow plugs so I told him to go ahead and replace them that way I wouldn't have to do it later. While there in there I asked about the oil in the air intake on top of the motor. The mecanic said he thought the seals on the turbo needed to be replaced and that in order to get to the back two glow plugs on the passengers side he would need to remove the turbo. He said he would also need a new gasket for the turbo when he reattached it. Waiting to here back from Banks on the cost of the parts. Really would like to know if this sounds right. My fuel mileage has been around 13 mpg even after I put in a 3.54 rear end and a NV4500 5 speed. Seems low to me. I've noticed that it uses about a quart of oil every 3000 miles. If its burning the oil that might explain the oil usage and maybe the fuel mileage (thats a guess, please feel free to chime in). He also said he advanced the timing one click. I don't know what that means but the truck sounds and runs the same. Am I in for trouble? Please share your knowledge because I don't have any.
Thanks for taking the time to read this.
Frank

[DmaxMaverick]

Where is the oil in the intake? Is it a coating on the inside of the intake manifold? If it is, it's probably normal. The CDR returns crankcase oil vapor upstream of the turbo. The 6.2's have notoriously messy intake manifolds, with or without a turbo. Worse with EGR, which you shouldn't have. Check the turbo compressor wheel for movement. It should spin easily when warm (some resistance but smooth when cold is normal), should have no end play (or extremely little, barely detectable), and side to side movement should be minimal, not able to contact the compressor housing at any point. 1 qt. oil consumption in 3000 miles is also normal (actually, not bad at all).

[Frank M. Hardcastle II]

Where is the oil in the intake? Is it a coating on the inside of the intake manifold? If it is, it's probably normal. The CDR returns crankcase oil vapor upstream of the turbo. The 6.2's have notoriously messy intake manifolds, with or without a turbo. Worse with EGR, which you shouldn't have. Check the turbo compressor wheel for movement. It should spin easily when warm (some resistance but smooth when cold is normal), should have no end play (or extremely little, barely detectable), and side to side movement should be minimal, not able to contact the compressor housing at any point. 1 qt. oil consumption in 3000 miles is also normal (actually, not bad at all).

The oil is all over the inside of the lid on the intake that connects to the turbo and along the circular edge that the lid sits on. Sorry I don't know how to get to the turbo compressor wheel or for that matter what it is. Please pardon my ignorance. The closest I can get to anything would be inside the air box where the K&N filter is. Thanks

[DmaxMaverick]

A generous coating of oil is normal in the areas you describe. Happens after miles and time. Clean the cover very well, and check it after about 3000 miles. There will be more oil.

This is a Diesel engine. If you had a really significant oil leak into the intake, the engine would not turn off. And, in many cases, will run away until it self destructs. Oil, any oil, is fuel. One qt. in 3000 miles is no where near significant consumption. One qt. in 1000 miles is acceptable by some folks, including GM in many cases. Much depends on type of use and driving habits. You're not close to alarming, regardless of how you use it. My 1985 6.2 uses about a qt. in 5-6000 miles, and has since new. The 1995 6.5 uses about a qt. in about 3-4000 miles, and always has. Both have very messy intakes, and always have. It's just the way they are. There's a few things you can do to minimize it, but they seem to run the same, clean or messy (to a point, of course).

The turbo compressor wheel is the impeller on the intake side of the turbo. You can view and access it when the duct is removed. The intake side is the shiny (or was, at one time) aluminum half of the turbo. The cast iron rusty part (or gray, if new) is the exhaust turbine. When you remove the duct and can see the wheel, you only need to grab the nut in the middle of the wheel. Move it all around, as you can, and give it a spin (don't press on the blades). Move in and out (push/pull, end play), side to side, making sure it is not able to contact the compressor housing at any point. Also look for evidence of contact, like score marks on the inside of the housing or chips missing on the blade edges, where the wheel would hit, if it could. If there is evidence of contact on the housing, but not on the wheel, it just means there was a previous failure, and it was repaired. These turbos (as with most any turbo in use) are amazingly durable. Many never wear out. I know of several million mile + class 8 trucks with original turbos, and they run under heavy load (boost) most of the time. Clean air, ample oil supply, and reasonable temperatures are key.

[Robyn]

The turbo in the GM rigs has a Bronze bearing that is fed with full line pressure oil right off the main oil gallery.
As long as that oil flow is constant and reasonably clean the turbo will live a LOOOOOOOOOOOOOOOOOOOOOOOOOOONG time.
One secret is to let the turbo cool a little before shutting the engine off after a hard run.

This cool down allows the oil to carry heat away from the bearing area and for the cooler "Idle speed" exhaust flow to cool the turbine down too.

Hot shut down without allowing for a little cool off can cause the oil thats left in the tubo bearing to boil and burn, eventually turning to a carbon over time.
This will and does cause the oiling of the bearing to become compromised and the result is a failed turbo.

At 200K miles Plus I ripped the turbo apart while doing a rebuild on my 94 Burb.

There was a small amount of carbon right behind the turbine wheel (Hot side) and some crud internal but nothing really frantic.

The oil residue can be caused by (As Maverick mentioned) the CDR venting and this is normal.

There is also the possibility that the oil seal on the compressor side of the turbo is allowing oil to seep past and into the air flow.

If this is a Banks turbo the inlet side of the turbo has a rubber "Boot" or hose attached and this can be removed to inspect things.

As was mentioned the GM 6.5's are notoriously sloppy with oil even when the engines are in good shape.

My 94 has been very clean since the rebuild. This is a result of a very good set of rings and minimal blowby.

The CDR valve is designed to allow for a small vacuum to be pulled in the crankcase. This vacuum keeps oil leaks to a minimum and also takes a lot of the load off of gaskets and seals that would otherwise be subject to a lot more seepage.

If the CDR becomes dirty and non functional it can allow too much vacuum in the crankcase and also too much oil vapor "Pull Over".

An engine that has a little too much blowby will also be a lot more sloppy in the intake.

I had a 93 6.5 TD that I bought new. At the first air filter change, I was apalled at the amount of oil in the turbo inlet.

All pretty much normal.

Try removing the oil fill cap with the engine idleing, there should be a light amount of oil vapor emitiing from the opening. If the vapor is more like gray smoke and in large quantities therein lies the issue.

Excess blowby will result in a far sloppier intake.

Keep us posted..

best

Robyn