A Funny, Smoky thing happened on the weekend...

[royzell]

I was towing my car trailer, loaded up the Malahat on Sunday (a sunny warm but not hot day). A long steep grade, I watched my EGTs and took it easy. At the top, just before starting down, we stopped to look at the view and take a break for about 10 minutes. I shut down the truck.

I got rolling again, downhill for a ways (by Bamberton) and took no time to get up to 60-65 mph. I was coasting along taking advantage of the free travel for a minute or so. I put my foot back into it and there was no response. I looked in the mirror and saw a huge cloud of blue smoke by the right rear of my truck.
I didn't know what I had, it scared the c@#p out of me, so I got stopped and pulled over right away. We bailed out and could see blue smoke wafting out of the exhaust pipe. I checked for rubbing tires, anything unusual under the hood etc. and could find nothing. I fired it up again and it ran fine except for pushing lots of blue smoke. After a couple minute of idling, test revving and realizing BCAA couldn't help for free I opted to get under way again, cautiously.
After 2-5 minutes of driving the blue cleared up and all was normal again. It hasn't done it again since.

Speculation as to what happened ?

[catfish101]

With these motors that don't drop the crankcase pressure to the ground they can get oiled up in the cylinders from the intake air that is blended with crankcase blowby. My 94 will do it when I haul something fairly heavy like a farm tractor.

[PLC7.3]

How full is the oil....... best to keep the level just above add....... check after a 10 minute drain down HOT.

You appear to have an aftermarket Turbo..... where does the oil drain into after turbo oiling.

R click on my name and email me I would like to see your turbo setup I will email you back.

[royzell]

I'll check oil. turbo oil drains into left head through fabbed opening in valve cover.

[444dieselrod]

my guess is that on decel you lost alot of heat in the cylinders and when you got back on it burned out some oil out of them. you might have even had some oil collect in the exhaust and it burned off too.

Diesle rod

[royzell]

It did it again. Last Saturday morning i was towing my empty car trailer on the same stretch of downhill road. I checked my mirror, huge cloud of blue smoke. Engine stalled.
I pulled over, restarted, and drove away again in a cloud that cleared up in a couple minutes. Irritating..., especially when it stalls.

[Blueovals&Blacksmoke]

do you have that tuna can looking thing on the back of where the air filter used to be? i cant remember the name of it but if they go back they will fill up with oil and dump it into the intake... i know the idi 6.9's have them but im pretty sure that the 7.3L idi's have them aswell

[Dodge/Cummins]

CDR? I think it stands for Crankcase Depression Regulator or something like that. The way I understand it is it's sortta like a PCV valve for IDIs.

Gotta' RINSE it out with gasoline, no blowin' it out with an air nossle. If the internal diaphram is broken and chunks come out of it you have to replace it.
The 7.3 Turbos have it on the driver's side valve cover. Not sure about NAs or non-factory turbos.

This is pretty basic stuff I learned about I think the first day I was on this site so you may know about it already. Especially if you put on your own Turbo "kit" and had to relocate it.

No offense to Blacksmoke, I just thought royzell probably already knew about it and I didn't want to take credit for knowing what to do with it, I learned about it on here.

It is a VERY possible cause of the problem though.

[LilDuke]

My truck would regularly do this. I figured it out as being the timing was too retarded, along with the engine cooling down too much going down hill. Note: I also had the smoke in winter/cold start.

[royzell]

Thanks guys, I'll check on the CDR and timing. The guy who installed my turbo a few years ago knew everything (he was the first to tell you that) but I've had a few problems due to the way it was installed. I'm learning more as we go.

LilDuke, were you thinking pump timing or engine timing ?

[royzell]

Hi again, I just checked for the CDR, and can find - - nothing. No tuna can. There is a hose running from the engine block behind the intake, plumbed into my air intake before the turbo. There is no filter or anything in the hose.
I just sold my parts truck so can't check against that.

Is it possible that while coasting, oil and fumes from inside the block get sucked into my intake and cause the smoke show ?

[David85]

I think its possible that you are getting liquid oil in the intake. Does the truck have a tendancy to surge at all when this happens?

Heres what I would do.

First make note of the conditions that will cause this to happen, you will need to make it repeat this for what I am about to suggest.

Get some hose thats the same size as the vent tubing that is currently installed.

Get two lengths of hose and connect one to the vent exit from the engine (you mention engine block, but I think its routed from the valley pan) and the other to the turbocharger inlet.

Temporarily install an old oil jug under the hood some where.

Now route the two vent lines to this oil jug.

What this is, is a crude oil trap. If oil is indeed getting blown out the vent hose into the turbo than this will catch it and you will have your answer of what is going on with the engine.

I had to track down a drain back problem with a diesel ranger that did what you are describing, only a lot worse. Very scary stuff.

[royzell]

Hi David, you're right,I meant the valley pan. I haven't noticed any surge, but I was coasting when it happened. I saw smoke in the mirror, put my foot down, and the engine sputtered and stalled. I'll try the hose and jug suggestion as soon as I get a chance and go back up to the Bamberton stretch of highway. I live pretty close.

[David85]

That ranger would also do it coasting or at very light load going downhill and did it once or twice running hard going flat out on the highway. Mainly did it at idle power settings though. Maybe the larger prechambers that the engine has were why it decided to eat the oil and turn it into power instead of simply stalling, who knows.... Tough little motor now that I think about it. In that case the drain galleries in the head were not drilled out to a large enough size (long story).

Keep a close eye on the oil level just in case. If you are loosing a noticeable amount after a short trip than its likely that the engine is ingesting liquid oil and not relatively harmless oil mist. I'd install an oil trap of some sort before driving it any more if at all possible just to be on the safe side.

[royzell]

I haven't had a chance to do the driving / oil jug test yet, but I just pulled the hose off the air intake (from the valley pan) and stuck a long screwdriver in it. It came out coated with black motor oil. Also, the connection where the air enters the turbo from the intercooler appeared to be leaking some black oil. I tightened the clamp.
The truck doesn't lose much oil while driving (it leaks it all into my yard). For some reason there is only the one location where I have had this experience. I have coasted down lots of other hills with no smoke or stalling.
Hmmm ??