I've been getting some grayish/blueish smoke on cold starts lately and decided to do some investigation to see if there was a problem or just the cold temps.

I googled it and turbo oil seal problem was pretty common so I figured it was easiest to start there. I removed the pipe between turbo and CAC and it had quite a bit of oil it in. The pipe after the CAC had a fair amount as well. I checked the oil level in the engine and it was slightly down but I can't say how accurate the dipstick is nor it was completely full after the last oil change. Either way, not much oil is entering the intake but I would assume any is too much.


Here's my main concern -

What's the likelyhood of getting a runaway from this?? Is it possible for the oil seal to fail 'more' than it already has putting more oil in the intake allowing for a runaway condition?


Obviously the turbo needs replaced but is it safe to run it the way it is until it completely fails or replace immediately?

 

I'd have it pulled. They will check that on a trade in inspection. When you said turbo seals, this is what I thought you may have checked. It happened on my 6.0L as well. I replaced the turbo on it the following weekend, so I can't tell you how long it will last, but I'd take it easy for sure.

 

Are we sure that the residual oil is not crankcase blow-by? I know there is a separator on the motor but how good does it work.

 

i had this seal replaced in Dec. and its still leaking ( bc3z 8590 L ) very little but it leaks.
? bad turbo don't understand and a runaway what is that all about sorry for the newbie ? just never heard of a runaway

 

Runaway is when the engine draws oil through the intake or around bad valve seals and actually runs on the oil. The term runaway came about because the old Detroit 2 stroke engines would literally run wild until something let loose on them. Unlimited RPM because there is nothing to govern the fuel source. The only way to stop them is to cut off the air supply.

My dad drove tractor trailers with Detroit engines in the early 70s. They had the fuel rack stick open on a 6-71 in the shop and the mechanic pulled down his pants and stuck his bare butt on the intake tube to snuff the air! I really don't think I would go that far to save somebody else's engine, but a good CO2 fire extinguisher would probably do the trick.

 

Would there be oil from the breather in the pipe leaving the turbo?

Any way to tell for sure if the turbo seal is leaking? If it's not the turbo, then what is making smoke on startup?

 

Take a look at the intake pipe prior to the turbo which is where the crankcase ventilation is introduced into the system.

 

Check here buddy....

https://www.ford-trucks.com/forums/1...ac-outlet.html

I am thinking runaway is very, very unlikely.

 

Ok, so maybe the oil in the intake doesn't mean turbo seals for sure but then let me ask this -

Why am I getting some nasty smoke (grayish/blueish burn your eyes type) when the truck has sat for a day or better. It's not pouring out the exhaust but easily visible and clouds up the garage if left inside idling. After 30 secs or so of running it's like it never happened. Nothing has changed in almost 2 years with the engine. It's been doing this for the last few weeks/month maybe but not every start.


Something has changed/broke/etc and I'd like to figure it out before a catastrophic failure that's not covered under warranty.



It almost acts like it has a couple bad glow plugs but the smoke is the wrong color and it starts just as easy as it always has.


Any insight/info is appericated, even the far out stuff!

 

Although I believe runaway is unlikely, it is possible with a bad turbo seal. I'm going to say that it is unlikely for a turbo seal to fail on its own with no other turbo symptoms. Generally the turbo shaft will have quite a bit of play in it prior to a seal failure.

 

seems to me if you are getting oil after the turbo then one might consider pulling it and having a look at it.

 

Seems like oil after the turbo is SOP for the 6.7. I don't know whether to be happy the turbo is likely fine or concerned that whatever is wrong is worse.....


Would a bad glow plug set a CEL?

 

bad glow plug would set a cel.

 

What all could be creating the smoke at start up?

Obviously oil getting in the combustion chamber - what are possible ways this could happen?

What other things??

 

Our VP at work was telling me how he needed to rebuild the turbo on his 05 Duramax. He's been talking about it for months and since he is a pretty capable guy, I never questioned him about it. Finally the subject came up one day and I asked how he knew it needed a seal and he said there was oil leaking from the CAC tube at the bottom of the cooler.

His brother had noticed some oil seeping from one of the boots at the cooler and they pulled the tube from the turbo and found oil in the tube all the way back to the turbo so they assumed it was a bad seal. After I explained to him that it is very common on these V8 diesels for oil vapor from the PCV system to condense and collect in the intercooler and piping, he did some more investigation and finally decided that the source of the oil was not the turbo. He was ready to spend $800+ for a reman turbo and probably 6 hours of his time for the swap.

With all that being said, the centrifugal oil separator on the 6.7 should be catching the majority of the oil from the PCV system. I don't know much about the system and thankfully haven't had the need to have the intake off the truck to see if there is any oil present. I guess it is possible that the separator could malfunction or maybe it just isn't all that effective. It is possible for a bad injector or two to cause the symptoms that you are experiencing.