Engine Attitude - Sometimes nails, sometimes doesn't
 

I have a 350SDL (please withold the obvious comment) that was nailing quite a bit before I put in some new Bosio nozzles. Still nailed after the change, but then I put a 500 mile road trip in and the car sounded like a sewing machine (like it was running WVO).

A few roadtrips later and it started nailing like crazy again. Dumped some ATF in the tank to see if that calmed it down a bit to no major improvement. Another 250 mile roadtrip and it seemed a bit better. Then 250 miles back last night and the engine is back to running like a sewing machine.

What gives? Am I getting some bad fuel from time to time? Do I need to drive the car like I stole it for 200 miles when it starts acting up?

Any thoughts on the random nature (or maybe not so random) would be appreciated

Thanks

Bob

Check your timing chain tention and IP timing would be my first guess.

It has been my observation that plain diesel fuel is just inadequate. You're most likely dealing with partial injector clogging and low-cetane fuel. The solution may just be using a good injector cleaner and cetane enhancer. I don't recommend dumping ATF in the tank. Is it nailing at idle or while cruising?

nails only at idle. Runs great otherwise and will cruise at 80mph no problem.

I'm skeptical on the clogging since these bosio nozzles only have about 2000 miles on them. Also, it's the random nature. Right now it's running great, but who knows maybe next tank it won't run so great.

Another possible key point is that it only gets driven 1-2x/week.

Dumb question time:
I keep seeing the term "nailing" referred to a lot, and as I am still fairly new and soaking in the diesel world, just what exactly is nailing? I just gotta ask...
-Chris

I'm no expert on the combustion details, but I know it when I hear it. It's the metallic 'diesel' pinging that occurs generally at idle and as I understand it is due to premature combustion of the fuel caused by bad timing, injectors dripping etc.. There's many reasons why it can occur, hence my reason for asking as I'm at a loss of why mine nails only some of the time (really depends on the day and/or tank of fuel I bought)

Someone else on this forum has already given a good explanation so try searching a bit.

Sounds to me to be a fuel quality issue. Try a different fuel source for a while and see if the problem stays gone. I would also try using an additive, but not ATF. My personal choice is Redline, but there are others that many on this forum like as well.

If the injectors are spraying fine, and most likely they are since they're fairly new, it's probably just low cetane fuel. Try a cetane booster like Redline DFC or PowerService, though my favorite for boosting cetane is Amsoil's Cetane Boost but that one you'd have to mail order.

Cool. I'll give the cetane boosters a try. Thanks for the responses.