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Eye burnin' smoke!

Russell

3/4 ton status
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Hey guys!

I picked up an 86 6.2L K10 earlier on this year, and have been using it as an off road rig for most of the summer.

The truck has always produced smoke at an idle that goes away as soon as you start driving, and doesn't come back until a few minutes after you stop and let it idle.

Before I used to get a light haze behind the truck when accelerating, which is standard to these engines, but now I am getting a pretty significant black smoke even on a light acceleration, and getting a very large volume of thick smoke at idle / part throttle which burns the eyes, and does not go away until you get into producing black smoke. On the highway the truck does not smoke unless you put your foot into it / downshift to keep speed on a hill.

Normally I wouldn't worry too much about it, but my wheeling partners have been complaining about how the diesel smoke burns their eyes when I am idling around on the trails, and I've noticed a loss of mileage / power.

The part that concerns me is that the really heavy smoke is kind of on the intermittant side. Sometimes it is so thick that I have to hold my breath to run through the cloud to get into my truck and move it, or shut it down on the trail so I don't kill myself in the cab. When it is smoking heavily like that, a bit of throttle produces even more smoke, but a couple sharp revs will make it clear up a bit. Other times the smoke is still eye burning, but is light enough that it doesn't bother me too terribly much.

My first thought is worn injector nozzles making for a drippy idle / part throttle spray pattern, but that wouldn't explain the intermittant side of things.

The engine has a nice and healthy rattle to it, and I've already confirmed that my injection timing is good. I've got about 5 PSI of fuel pressure at the supply line for the IP, and have no fuel system problems. Both filters are fairly new, and clean flowing.

Any thoughts?
 
Injectors getting tired? When's the last time they were replaced or tested?
 
Is it black smoke at idle too? I know you've probably checked already, but is the air filter clean?

Does it use oil?
 
Zero oil consumption since I bought it, and the air filter was the first thing I replaced on the truck when I bought it :)

Injectors have never been checked, I'm kinda thinkin I may be needing to drop a few bills to replace them =/
 
If the injectors test good you might want to check compression. It could be getting low and that will give you smoke/low power
 
Nope, it wound up being a burnt exhaust valve on cylinder number 3. The engine started well enough that I never noticed an inconsistent cranking speed.

That engine wound up having an injection pump failure, so I replaced it with a new used engine. That engine suffered a couple spun bearings shortly after install, so I took the bottom end from the old one and combined it with the good top end / injection system from the new one and sold the whole thing.
 
Dang, I was hoping to hear about the before/after on an injector change out. I've beeen reading alot in the past few monthe since I bought my 6.5 and am wondering if my little bit of excess smoke is injector related. I read an article on The diesel page where the guy replaced his old timing chain with a DSG gear set and said it smoked less, started better and pulled better. I'm thinking about doing that first. I dunno, it's about the same price as a set of marine injectors.
 
I'm not sure I'd suggest buying marine injectors for a naturally aspirated engine. My stock injectors and 6.2L C code injection pump are plenty capable of horribly over-fuelling my turbocharged engine as it is!

Timing chain is likely a very good idea though, every single one of these engines I've opened up have been needing a new one for some time before I cracked them open. Just make sure you take the truck somewhere to get it timed properly after you finish up. I was pretty amazed at how precisely the timing is set on these engines, there is no way humanly possible to set it dead on without a timing tool.
 
Mine's a 6.5 TD. Do you think some marine injectors will over-fuel it? I was looking at the ones from SSDiesel and they said "+40 hp" which of course had my eyes all aglow.
 
Maybe 40 hp at sea level with extra boost! Way up in Colorado, you probably won't see a whole lot of gain over stock injectors. If your nozzles are finished, you'll notice a major boost in power even with stock replacements :)
 
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