cmac2012

A couple of weeks ago I noticed a sort of loud sputtering. That’s what it sounded like in the cab anyway. I checked everything, oil was in the lower range, I added more, the next day the noise was gone.

It keeps coming back, usually after a long-ish freeway trip. Last night when I got home, I took this video/audio:


This morning I went for a short drive, when I got home I took another recording:


Intermittent problems drive me crazy. I don’t trust it when a problem heals itself. Odo reads 186K approx. When the noise is really happening, I start imagining shopping for a long block or a new truck.

My stethoscope is down at my storage. I’ll give it a good listen next time I’m down there, I’ll see if I can find where it’s coming from.

Triaged

I'd start with looking for an exhaust manifold leak from a broken bolt as that's a common problem. That does sound bad and could be a rod knock but hard to pinpoint the noise from video. No forbidden glitter on the dip stick? If it's not an exhaust leak I drain the oil and cut open the filter. Stethoscope or piece of hose would be best to find the location. All the other fluids look good?

cmac2012

That is wonderful to hear, the possibility that it might be an exhaust manifold bolt. Certainly not proven yet. It’s interesting though, because about two months ago, I had some time on my hands, visiting my sister in Washington state. She had a big open garage, I had the wild idea to maybe get the heads done and at least get new intake manifold and valve cover gaskets. It became clear I didn’t have the tooling or the time to do the heads but I did the rest. However, I took the exhaust manifolds off first in preparation, and had to put them back on of course. The bolts were old, I reused them.

OMG, what a happy day that would be, if that was whence the noise cometh. I hadn’t heard of that before, but it makes sense. Every exhaust stroke, t’would fart out hard, into that loose manifold, loose at that point, and give a quick bang.

I need to stay on earth until I know for certain though. The fluids all look really good. And the way it sounds so nice in the morning - it seems like the rod would just keep knocking. As to why it would heal up, temporarily, who knows. I’ll get that stethoscope tomorrow and get busy. I would sure like to get another year or two or three out of this thing before the long block is undertaken.