6.5 white smoke from #2 problem

Last week I bought my 98 k3500 with 6.5 turbo and 5 speed trans. I drove it for a week and refueled. About 4 miles later I got a bad miss with white smoke. I did some sniffing and found it was likely a bad injector. While idling cracked the fuel line to number 1 3 5 7 with no change. cracked 2 and the smoke stopped. Tightened. Smoke again. Repeated this 3 more times. I found my injector. with some patience I was able to replace it with a brand new one from advance auto. Got it back together. No change. Cracked the line again. No smoke. Tightened it. Smoke. I'm not a diesel guy so in pretty much lost and going by what I find on these forums. What should my next course of action be?

Welcome aboard!

Good job identifying the suspect cylinder. Textbook, to put it simply.

You have a dead cylinder. It's not making heat, more specifically, it's not making compression. Depending on your urgency, you can try some MMO (Marvel Mystery Oil) or ATF. If rings are stuck, either can help to free them, but it takes some time running (horribly) to work. Keep an eye on your coolant level and condition. A leaking head gasket often sends the combustion gasses into the coolant. A leak large enough to cause a dead cylinder won't respond to any coolant sealant remedy, so don't bother.

If that's not an option or it didn't work, I'd start with removing the valve cover, to be optimistic. Check the rocker retainers. They are plastic, and keep the rockers in position on the rack, and when they fail, can allow the rockers to walk along the rack, and interfere with valve operation. A broken valve spring is also a possibility.

Other possibilities involve getting deeper into the engine, more resembling an overhaul. Head gasket, rings, etc. or worse.

Well I'll be ordering valve cover gaskets today but until I get them I'm putting about a quart of atf to work. Thank you for the reply.

Don't use valve cover gaskets !
You will have endless leaks on the top of your engine making a huge mess
The factory used RTV/silicon.
Clean all surfaces and make sure the valve cover is flat especially around the bolt holes.
Use an appropriate size bead on the surface,set the cover on and tighten the bolts a little,let the RTV set up overnight and then finish snugging up the valve cover bolts in the morning,or appropriate time for the RTV to set up.

Yes. Do not use valve cover gaskets, as a general rule. RTV is the solution. The same applies to the oil pan. I like "The Right Stuff" in the Cheese-Wiz can (it's crazy simple, one can does both VC, or one oil pan), but you can use a squeeze tube and save a buck or two.

Now, if you're planning on repeated valve cover removal, use gaskets until the R/R is done. Clean well and seal it up with RTV as described by Yukon when you're done messing with it. Snug the bolts hand tight (with a socket/extension, but no ratchet) until cured, then to book torque. I like to remove the bolts and apply a dab of RTV on the threads before final torque (or a little less) to prevent loosening later down the road. Over-tightening only bends the covers and leaks after a while.

I would get a compression reading on the beast.

The fact that the issue just all of a sudden happened raises questions ?????????

When was the last time the fuel filter was changed ???
Any unusual noises....????? Knocking, clattering (Other than normal diesel noises)

Unplug the fuel shutoff solenoid on the injection pump and then hit the starter and pay attention to the cadence of the engine as it turns over....a dead cylinder will be very obvious... it will present as a very much out of the normal sound in the scheme of things as the engine turns over "ZA ZA ZA ZA ZA ZAAAAAAAAAAAAAAA ZA ZA.. A dead hole offers little resistance and the difference is quit noticeable..

You can learn a lot about whats going on before you start ripping stuff off

Access to the RH side of the engine (Glow plugs) is easy as pie....remove the R front tire/wheel and the rubber inner fender flap..

You can then reach many things...GLOW PLUGS...Starter front bracket and wires...all without removing the turbo and such. Sit on a bucket and work on it...

Keep us in the loop.

Seems to have valve clatter. I've driven it 40 miles or so in the last week with trans fluid in the oil. The fuel filter was changed the day I bought it. I owned it exactly seven days when the trouble started. talked to a local 6.5 killer ( he modded them in the 90-00's too much) he walked me through taking the valve cover off without turbo removal. I'm hoping to have time to tear into it next week. I appreciate the advice.