I noticed blue smoke coming out of the tailpipe today... uh oh.

It's only at very certain times though... maybe that can help diagnose what the cause is. The truck was warmed up (had been driving for at least half an hour on the highway). Though, warm is only N on "normal" on the gauge (see my other post). It happens when switching from engine braking -- down a hill -- to accelerating, at the bottom of the hill. It only does it under very light acceleration -- once you hit the pedal harder, and the turbo kicks in, it goes away. And it only happens if you've been engine braking down hill, then switch to light acceleration. When going up hill, switching from light to heavy acceleration and back doesn't produce and smoke (at least visible in the rear view mirror, like it was when switching from going downhill to flat). But, for a few seconds, it was pouring out light blue smoke enough to obscure part of the road behind me.

I do get black smoke if I lug it, or accelerate really hard, but generally, no black smoke.

 

sounds to me like valve guides and or stem seals.
Rob

 

Sounds like a turbo seal.
You have one of these too? I swear, you and I keep winding up with very similar vehicles, although I ditched the Subaru. Family doesn't fit in it anymore.

 

yeah.... I still have three subarus too (though the newest one is for sale -- only keeping the old ones).

I've got a little more info on it... it seems to be very related to throttle position. At fully off of the throttle, no smoke (or very little). On the throttle, no smoke. It's when I'm just barely on the throttle that the big cloud comes out. By modulating the throttle, I can get very distinct separated puffs instead of a long blue cloud.... not that that is very useful, but it's funny how controllable it is.

And.... I don't think it was doing this before wednesday this week. It didn't come on slowly, but all of a sudden.

Z

 

So.... if it's turbo seals (I've been reading a lot, and it seems that it likely is). Especially, since it only does it after the engine is very warm -- like 30 miles into a drive.

Where do I get new seals/rebuilt turbo/etc..... is this a dealer only item? How much are we talking?

And, on a related note... how long do I need to let the turbo cool down after parking the truck, before turning the engine off? I had been letting it idle for a minute or more, but I'm thinking perhaps more like 5 to 10 minutes -- when I got home the other day, the exhaust was HOT -- like too hot to hold your hand 8" away from the tip of the exhaust. It took a good 5 minutes+ to get back into the normal idling temperature range. I don't have an EGT, but maybe I need one? I'm wondering if I may have contributed to cooking the turbo seals but shutting it off hot? (I live at the top of a good 4,000 foot elevation gain, BTW, so when I get home, the turbo has been under pretty good use for about 20 to 30 miles usually).

Thanks

Z

 

What brand of turbo kit do you have?
Rob

 

No idea.... as far as I know, it's the factory turbo (it was sold as a 1994 model year, even though it was manufactured in late 1993).

 

I always wait until my pyro is at 300* be it 3 minutes or 7 minutes all depends on if I was on the turbo, I try to go into idol mode about 1 mile before I hit my destination too keep idol time down...

 

Take the turbo off and have it rebuilt. A quick search on Google shows a few in the greater Denver metro area, it's a pretty specialized industry.
As far as the exhaust heat, that sounds excessive. If you have a non-contact pyrometer (laser thermometer) try to get a reading of the exhaust pipe temp right after driving, it'll be less than the actual exhaust temp, but will give you an idea. You may have an overboost issue.

 

Update -- it looks like the CDR valve may be bad -- it's sending a lot of oil into the intake. I've got a new one coming in from fordpartsgiant.com (have to give them the ford part number to find it). We'll see how it runs with that replaced

 

I saw your update on gmail, I didn't know the CDR could make it smoke like that. Mine gives a little haze while the RPMs are dropping after revving it up, but it doesn't smoke on long downhills.

 

My rig had the same symptoms (started as white smoke while engine braking) and went downhill from there...ended up being a HG.

 

Update -- not getting any better

I replaced the CDR, but no difference. It does light blue smoke on downhills and while idling once warm, and heavy blue smoke under light throttle -- but no blue smoke on heavy throttle. And a little blue smoke when cold started, but not bad for a diesel at least.

And... as of the last few days, the oil pressure is not looking good now. It used to sit in the middle -- now it's down by the N in normal, and if I am at high boost on the turbo, it'll go down even more -- about a letter's width below the N. Goes back to the N as soon as I let off on the throttle. How the heck can turbo boost affect oil pressure? I did check, and it's got enough oil (kind of black, I know I need to change it - I added a quart today to get back to full). Oil pressure does not seem to change with engine RPM or temp otherwise. But it's definitely not where it used to be -- could be a bad gauge I guess, but I'm kind of worried now that something major is failing.

Anyone know a good diesel mechanic in the Boulder/Denver area for these engines? My usual american vehicle mechanic does gassers, but not really diesels.

 

if the truck is burning oil ..ushould see it on dipstick as oil loss... oil pressure can drop under hard excelleration due to blow by pressure in block. all engines have some blow by...if it was some kind of oil leak in the turbo it would smoke all the time... valves are oiled by splash in valve cover valve guide seals can break and fall off. alowing oil to migrate down valve during decelleration.. hard to see oil smoke at startup, the only other time oil moves down the valve,,if you are not burning oil...it is fuel related..likely a injector...it will ether go away or get worse...wait and see..good luck

 

From what I have seen, the only time you'll see blue smoke from oil ingestion is on overrun. Mine does this a little, if I rev it and let off it'll give a puff of blue. I cleaned the CDR (there is oil in the intake) and it helped a little but the CDR probably needs to be replaced.

I don't know which turbo you have, but you should be able to pull the adapter from the turbo to the intake and see if there is oil in it. There likely will be some even if the turbo is good, but in your case there would be a fair bit of oil with signs it had been moving, possibly pooling if there's space for that. If it's just a film then I wouldn't worry about it as a source.