4BT work truck suddenly blowing smoke, need diagnosis
 

Hi, my name's Alex.

I'm a welder and blacksmith. I drive a 79 F150 that I've owned for 8 years, and two years ago I put a stock 4BT, and a ZF5 into it, to improve fuel economy. I've loved every minute of it, and was getting 21-22 mpg, with rock solid reliability, until today. I'm right in the middle of installing the biggest job I've ever done, three months of fabrication leading up to it, and today my truck started BLOWING smoke from the exhaust. :scare2:

I have a low hood stack, so I can see my exhaust very well. I was driving to the site this morning, and I noticed a few puffs of white smoke here and there when I first got on the road. I didn't think anything of it, because it was one of the first cool mornings we've had this fall, and i figured it was just a little moisture in the exhaust. Then I noticed that I could see my exhaust more than I usually can. It wasn't smokey, but it was visible, which it usually isn't. I still didn't think much of it. I drove half an hour to the site, shut down normally, and parked. I had to move my truck twice for other trucks to get by me, so I ran it for about a minute each of those times. Late in the morning, I had to run out to get some supplies, and when I got a few minutes into my drive, my exhaust started getting more smokey. The smoke looked a bit blue. When I came to a stop and pushed in the clutch, and the engine dropped to an idle, it started giving off big milky puffs of white smoke, with some blue or grey mixed in. I drove to Lowe's, and it got very smokey. It was leaving easily visible clouds of bluish smoke behind me. When I idled in the parking space, it put out quite a bit of milky white and blue smoke. When I started it up after Lowe's, it blew more white and blue smoke when it started and as I drove away, but at the end of the fifteen minute drive back to the site, the smoke cleared up VERY SUDDENLY. At the top of the road to the site there was a big cloud from where I let off the gas and put in the clutch, and by the time I got to the bottom, my truck was running so clean that my friend didn't know what I was talking about when I told him that my truck was having a problem. I worked for a couple more hours, and started my truck up to go home. It gave off more smoke with this start, and over the half hour drive home. It also started making popping sounds every once in a while, like something was igniting in the exhaust maybe. The smoke usually seems to be intermittent, like it's not coming from all the cylinders. You can just see clear and smokey patches alternating when idling. I got out and looked at the engine while it was still running, and smoking, but when I got back in the drivers seat to keep testing it (no shutoff, continued run), and I drove 3-4 miles around my area, there wasn't any smoke or noise at all!

Does anyone know what's going on?

I'm already deeply screwed with this job, but if I keep driving my truck and ruin the engine, it'll obviously be much worse.

I appreciate any help, Alex

Alex it sounds like an injector leaking Intermittently. The white smoke is probably unburned fuel and can wash the oil off a cylinder wall and score the piston. You Might try some lucas fuel conditioner there is a chance maybe it will help. Injector nozzles or complete injectors would be a good start otherwise.
How many miles on this 4BT? got any gauges for boost? is it still making normal power?
take a sniff of the white smoke and see if it smells like raw fuel.

I'm having the same issue, only with a F350 (recently replaced stock exhaust with 4" Diamond eye w/cat deleted, and Airaid cold air kit). I thought it might be the EGR, so I replaced that, smokes a little less but not cleared up by any stretch. Not hijacking, but following.....

Based on the description, I'm gonna guess turbo seal leaking oil into the exhaust.