PeachParts Mercedes-Benz Forum - snap, crackle and pop?

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Also sounds like wheel bearings going bad.

Tom W

Is the noise like what you get when you throw 87 octane ( or bad gas) in the blown Miata? This previous statement is about dead on! Albeit just a little quieter, but the noise is extremely similar.

Quote:

Originally Posted by WINGAS (Post 1541137)

Its difficult to define a noise with written words... you might peruse my post on diesel pre-ignition to see if there are any tidbits of wisdom there. Is the noise like what you get when you throw 87 octane ( or bad gas) in the blown Miata?

Sure fire way to see is to add some cetane boost to the fuel, or add bio. I have a heavy mix (16 ozs to 20 gals) of cetane boost in the car now, as well as reconnecting the EGR and the issue is mitigated, but not gone. Biofuel ( with a cetane north of 50) is the next step.

If its an pre-ignition engine noise, try cetane boost and see if it helps.

I'm also going to see if I can richen the mixture at part throttle by adjusting that "hat" thingy. When I figure out exactly what that " hat thingy" on top of the IP actually does. :confused:

It could be something as simple as an exhuast leak, which even at idle, with a 3' small rubber tube ( winshield washer size) in your ear as a stethoscope, you'll be able to discern.

When I bought some bad premium fuel for my 10.5:1 compression gas engine, it was LOUD. Guys playing the "spoons" under the hood. ( I quickly disconnected the vaccum advance and stopped it) Diesel pre ignition is a bit quieter but not much. The MBz engine bays are also well insulated.

Throw some cetane boost in the tank during the next fill up. The new low sulphur fuel plain sucks for older, higher compression diesels. I;m having a helluva time with my 95 on the stuff.

As in your case, there might be other mechanical issues at play here.

Now, nailing is very simlar, easy to confuse the two, as I have found out in my short two months as a diesel owner. Running some Diesel Purge directly through the system might help that.

I'd condition the fuel first and see what happens. You guys have valves that, from what I read, are very easily adjusted. I;d defintely try that as well. Our "newer" models have hydraulic lifters and dont need adjustments, which kinda stinks as it was the first thing I was going to try. Very used to adjsuting valves on solid lifter motors, albeit with funky MBz wrenches here!

Condition the fuel. I liek Howes for lubricity but have only tried the Power Service cetane boost so far.

I changed the primary and secondary fuel filters and the noise seems to have gone away.

Go figure.....

Hey, we like it easy.. thats cool. Might have been running under pressure and starving it slightly.( lean)

Its back...just seems to be on acceleration bwteen 20 and 60mph

Try some cetane boost or bio in the fuel mix and see if it goes away.

It sounds like you both have something else mechanical going on. You should not need cetane booster for your engine to run without nailing. Maybe a bad injector or a damaged pre-chamber? Mine run just fine on ULSD under all conditions, the minimum cetane rating is still 40.

Did he say it was nailing?> or are you assuming. Look, I;m totally new to diesels but my 606 was BOTH nailing and going into preignition with ULSD.

Cetane boost cured the "rattles" on acceleration, as did bio. It still nails, which I beleive is a bad prechamber. Worse on bio, which I ASSUME is due to poorer atomization.

To wit, as I've recently discovered, diesels make more than one kind of sound, and its NOT always nailing.IMHO, his is suffereing from pre-ignition or post ignition, however it works in a compression engine. He'll find out by buying a $6 bottle of Power Service cetane boost and throwing half in the tank.

PS my 606 stopping pinging with the cetane boost, but lost some power. Not so with bio. No ping, good power.

Neumann, if you can get some biodiesel down there in sunny FLA, its what I'd recommend.

Quote:

Originally Posted by WINGAS (Post 1564143)

Did he say it was nailing?> or are you assuming. Look, I;m totally new to diesels but my 606 was BOTH nailing and going into preignition with ULSD.

Cetane boost cured the "rattles" on acceleration, as did bio. It still nails, which I beleive is a bad prechamber.

To wit, as I;ve recently discovered, diesels make more than one kind of sound, and its NOT always nailing.

What he was describing sure sounds like nailing to me, the last time I heard a sound like that I had a bad injector. As I said, if your engine isn't running correctly on ULSD you should find and correct the problem. You should not have to use any additive with ULSD. BTW, is your IP timing correct (it should not "rattle" either)? If you do have a bad pre-chamber, fix it before it causes more damage.