Is there a diesel mechanic in the house?
February 26, 2017 11:49 AM   Subscribe

I have a 2004 350 4-W drive pickup with 220000 miles on an . It smokes, but intermittently. I don't want to be a 'coal roller'!! I know there's some maintenance to do, but male friends have suggested it could be two separate issues: Could it be rings, could it be injectors, or could it be both? More below the fold.

I can start it cold, and it may or may not smoke, usually lightly. I can drive it 50 miles on the interstate, and it will not smoke. When I get into Boise, it will smoke heavily (belching black) at lights, if I happen to stop and leave it running, or if I shut it off, go into a store, and restart it while it's warm.

I lubs my big white beast, and I want to do right by him. Should I replace one or another--rings or injectors--and wait to see if that fixes it for another 50000 miles? Or do I bite the bullet and replace both (empty the savings account) on the premise that it will need done soon anyway, and it would be cheaper paying for a mechanic's time just the once?

Any opinion if I should sell the beast as is? I'm sure I wouldn't get much selling it to a private party. I really don't want to finance, so I'd be looking at a truck (4WD, towing package) that would be in the $5000-$7000 range, which again, will have high mileage.

The tranny was rebuilt last summer. 4WD was serviced at the time. Brakes and suspension have been redone within the last year. All the minor reoccurring maintenance has been done in a timely fashion.

Wut to do???
posted by BlueHorse to Travel & Transportation (4 answers total)
Black smoke is usually over-fuelling. If an injector is leaking that would produce this issue and is BY FAR the cheaper of the two options to try first. Theoretically rings can do this, but I'd have thought that injectors were more likely.

Is it a turbo? Because lack of boost can also cause this (ie you get too much fuel despite the metering being correct because you have not enough air volume), so boost controller or an intermittently leaking intake air pipe could also be doing this. I have had a car on a dyno that blew a boost line and it went from 'everything is fine' to "WHO TURNED OUT THE LIGHTS *COUGH*COUGH*"smoke instantly.
posted by Brockles at 12:01 PM on February 26, 2017 [3 favorites]

Could be the MAF sensor playing up. Cheap(ish) to replace, but you can often clean them (carefully!) with isopropyl alcohol and they’ll be fine for ages. Have you checked the obvious things like the air filter & the oil levels?

Black smoke == more fuel than there is Oxygen to burn it. Which means that something is causing the imbalance. Either there’s too much fuel getting in (bad injectors) or too little Oxygen (bad MAF, bad turbo / turbo lines, clogged air filter, EGR problems).

Unlikely to be piston rings, as oil getting into the cylinders usually results in blue smoke, not black.
posted by pharm at 12:06 PM on February 26, 2017 [3 favorites]

Take it to a diesel specialty mechanic and don't suggest either remedy. Choose one that has a dyno so they can replicate the driving conditions. A 2004 will have computer controlled injection, so it is probably a bad sensor (not the rings, that would be blue smoke).
posted by 445supermag at 2:49 PM on February 26, 2017 [1 favorite]

Sounds like injectors or other fuel system to me, an old ute of mine did very similar things. I didn't have the money to fix mine and a bottle of injector cleaner was a surprisingly effective short term treatment.

There's no need to guess though, a diesel mechanic should be able to tell you fairly definitively either way.
posted by deadwax at 9:15 PM on February 26, 2017

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