Intermittent noise, 300SDL - PeachParts Mercedes-Benz Forum

cmac2012 · #1 10-17-2017, 01:12 AM

Forgive me y'all, yet another 'guess this noise thread.'

I check my tranny fluid level a lot, about every two days, someday I'll put in new seals and/or rebuild it. Anyway, I've been noticing a funny noise that fades in and out. It almost sounds like tapping a penny on glass, like you might do on a door instead of knocking.

The vid was taken at night, now and then you can see that I'm moving the phone about, but the intermittency in the vid is very much like it was to my ears at the time, which were not being moved about. You can hear it for the first few seconds, then again peaking at around 12 or 13 seconds, then again at around 25 to 26 seconds, which indicates a strange regularity of cycle.

Seems to be 8 clicks a second. That would indicate one tappet move per cycle, one piston, correct me if I'm wrong.

http://youtu.be/c21_xj4mesc

t walgamuth · #2 10-17-2017, 06:36 AM

Sounded normal to me.

Diseasel300 · #3 10-17-2017, 03:33 PM

Sounds very similar to the injection "knock" my SDL was making when it had leaky delivery valves (the valves, not the seals). Mine was MUCH MUCH LOUDER though. It could also be the fuel you're running. I have never dressed the DV on Cylinder #3 and with certain station brands, I'll get that nailing noise in that cylinder. A bit of 2 stroke oil shuts it right up.

I wouldn't worry about it until it gets too annoying to stand anymore or gets really loud (Think someone hammering on an anvil). When it's loud/anoying enough to address, you'll hear it inside over the HVAC blower.

cmac2012 · #4 10-18-2017, 02:28 AM

I heard the hammering on anvil once. By then it was too late. Sad story.

Thanks for the feedback, I don't want to be neurotic, one thing that struck me about this was the fade in and fade out. Intermittent things worry me. Tonight it was more even.

So what with the 2 stroke oil? Do you put some in the fuel (note I didn't say 'gas'

).

Diseasel300 · #5 10-18-2017, 09:15 AM

In the fuel yes. Opinions range from 1/2oz to 2oz per gallon of fuel depending on who you ask. I've gone with the minimum amount, usually 8oz per fillup (I usually add 16 gallons of diesel at the pump).

Use the cheapest 2 stroke oil you can find for watercraft (TCW3). It is designed to be burned so a low-ash formula. We still had a couple of gallons from a boat we had many moons ago, so I've been burning that in mine. It does seem to help, not to mention the additional lubrication the extra oil provides for the IP internals.