Billowing smoke, losing power, but only sometimes

[CassT6]

My 2000 5.9 Durango has been running great since I gave it a tune-up a few weeks ago. Saturday morning as I was driving to town, it suddenly began billowing very large thick smoke with a bluish tinge. This was a massive, shameful amount of smoke that stopped traffic. This continued as I attempted to make it to town (about 5 miles). It was not so bad just cruising at low speed, but any time I had to accelerate at all it was really bad. Then it died. It did start right back up but had low power as I pulled it into a parking lot. This seemed catastrophic at the time. I left it in that parking lot and bought a car, convinced the Durango was toast.
Later that day when I went back to the Durango to get my stuff out, with the intention of calling the junk yard and having the thing towed away, I decided to start it to demonstrate how awful it was.
The thing started right up and ran like a new one - no smoke, good power, no knocking or unusual engine noises. I decided to drive it home. It ran great for til I was about to pull in my driveway, then it started blowing smoke, lost power, and died. After that it wouldn't start.That was Saturday afternoon.
This evening I started it again just to see what would happen. It again started right up and seems to be idling along fine. I don't trust it to drive at all but obviously the problem is not as severe as I feared. What would cause symptoms like this to come and go? Something about it warming up? Could a sticking valve cause this level of dysfunction? The PCV valve is broken off from where I tried to replace it but cannot get it out of the grommet on the valve cover but it did not break off where debris could have fallen into the valve cover so I don't think that it necessarily related.

I would like to keep the Durango around for hauling stuff and as a spare vehicle, if I can. Educate me, please.

[gmtech1]

Originally Posted by CassT6

My 2000 5.9 Durango has been running great since I gave it a tune-up a few weeks ago. Saturday morning as I was driving to town, it suddenly began billowing very large thick smoke with a bluish tinge. This was a massive, shameful amount of smoke that stopped traffic. This continued as I attempted to make it to town (about 5 miles). It was not so bad just cruising at low speed, but any time I had to accelerate at all it was really bad. Then it died. It did start right back up but had low power as I pulled it into a parking lot. This seemed catastrophic at the time. I left it in that parking lot and bought a car, convinced the Durango was toast.
Later that day when I went back to the Durango to get my stuff out, with the intention of calling the junk yard and having the thing towed away, I decided to start it to demonstrate how awful it was.
The thing started right up and ran like a new one - no smoke, good power, no knocking or unusual engine noises. I decided to drive it home. It ran great for til I was about to pull in my driveway, then it started blowing smoke, lost power, and died. After that it wouldn't start.That was Saturday afternoon.
This evening I started it again just to see what would happen. It again started right up and seems to be idling along fine. I don't trust it to drive at all but obviously the problem is not as severe as I feared. What would cause symptoms like this to come and go? Something about it warming up? Could a sticking valve cause this level of dysfunction? The PCV valve is broken off from where I tried to replace it but cannot get it out of the grommet on the valve cover but it did not break off where debris could have fallen into the valve cover so I don't think that it necessarily related.

I would like to keep the Durango around for hauling stuff and as a spare vehicle, if I can. Educate me, please.

If that PCV valve is stuck, it could cause the smoking issue. Allowing too much crankcase pressure to build. Haven't seen one cause a no start though. I'd replace that valve and see what happens.

[shorod]

The first thing I'd do is check the oil level and make sure it is fine. When it runs dry of oil, it may stop smoking too. And replacing the broken PCV valve would be a wise thing to do as well.

When it was billowing smoke could you tell if the smoke smelled like burning oil or more like unburned fuel?

-Rod

[CassT6]

Thanks for the responses! I couldn't be sure if it was fuel smoke or oil smoke. Kind of bluish dark grayish. It smells at the tailpipe like it is running rich but that is when it is not smoking.

I have been told it's sticky valves/loose valves/catalytic converter. Nobody knows. I can't see it being valves since it has never done this before and was so extreme when it did happen, but I'm no mechanic. Just seems to me like that would be a gradually worsening thing. Tomorrow I intend to get out there and check into it further.The first thing I will do is get that broken PCV out. Then check oil level. Then bang around on the cat converter and see what I get. Will definitely post back here, and continue to watch this thread for more advice.

[shorod]

A bad catalytic converter would not cause the smoke (either blue or gray) but it certainly could be destroyed by running that exhaust through the converters.

-Rod