93 GMC 6.5L Turbo, sticking valve (or lifter)
 

I have a valve sticking open (sometimes). If I get it on the highway and floor it, it will usually click and jiggle and stop sticking (for a while). I was told it was a result of the low sulfur fuel, and loss of lubricity. A diesel mech suggested putting trans fluid in the tank, which I've been doing, but not solving problem. Is there are product that might fix this problem without tearing the engine apart? PS 211,000 miles.
Thanks in advance.
dc

NO ATF. It's got friction modifier in it, and it'll plug off injectors, on top of wearing them prematurely.

Does it produce white smoke??

6.5 have a plastic valve retainer ring so it is possible that is what is broken. dont know how ULSD diesel did that but its possible. describe the sound better

Updates??

Please update.

thanks for your replys
 

I've been framing a house in the great outdoors (Ohio) and it finally decided to get cold and wet.
When the valve sticks, the engine is making a sort of thump, thump sound that at first I thought was exhaust related. It is not.
It is now burning a whitish gray smoke almost constantly. Idle is rough, and it runs rough at about 35-50 mph, almost like a vibrating cell phone. It still has good power, and when I get it up to speed it runs at 70 almost effortlessly. It's at the lower speeds that it's so rough.
I bought some CRC (or equivalent) diesel treatment which was supposed to add "Lubricity", and it has really crapped out now (I don't know if it is just coincidence, as it has been getting worse). I do not think the valve ever stops sticking, and it sounded for a while as though it had a broken spring, which had happened earlier this year, but now the tapping is mostly down low in the pass. side of the engine, especially under load (uphill).
I am about to park it and wait till next year when I can afford to look for a replacement engine.
Again, thanks for your responses, and have a great holiday.
dc

IDK if it is a sticky valve. It's probably an injector, which is easy to test. Just crack the injector lines one at a time until the engine runs the same lope. Get it down to that cylinder, remove that injector and have it tested to see if it is bad. Might be able to get another to put in place to see if it helps the problem.

From the way you describe the noise and where it seems to be coming from and the blue smoke another possibility is a cracked piston or scuffed piston skirt and cylinder. The noise of a piston slap and a lifter noise are similar and it will drive you crazy trying to track it down. I had the head off of one engine 3 times before I figured out that the problem was a piston slap.

Updates??

If you find something, you can reopen this thread and update the progress.