Is this what nailing sounds like, and what should I do? - PeachParts Mercedes-Benz Forum

jnc19610 · #1 12-13-2006, 06:49 PM

A MY99 E300, with 65K.

I had a new noise this morning. I didn't quite pay attention to my glow, and the car starting with a clanking sound. Not quite rythmic. It went away after a couple of seconds. Definatly not a rod rattle. I thought it was nailing an injector and it settled down in a few seconds so, I figured I'd go on with my 134 mile commute.

It clanked again this afternoon. (more like pinging with a gas engine, but much heavier) I'm pretty sure this is nailing. So.... is it?

I was down to a 1/4 tank on fuel, so I figured I'd fill up with new fuel, in case this was fuel related. They didn't have any 'diesel purge' at the Sunoco station, so I had to settle for the diesel fuel conditioner that they had (stp).

I made it home, and the car sounds fine. I'll see what it sounds like in the morning when it's cold.

So..... is this nailing? Maybe new glow plugs? Maybe have the injectors checked? I"m pretty new at this diesel thing. Car runs fine, I just don't like the startup noises. (there are no check engine light. I haven't checked for pending codes yet, I might tonight if I have time)

Ideas...... (newbie appreciates help)

Thanks.....

kerry · #2 12-13-2006, 07:07 PM

Take your laptop out in the morning and record it. Then post the file on this thread and you could get some decent answers.

Parrot of Doom · #3 12-13-2006, 08:07 PM

When did you last change your oil?

Mine was about 10,000 miles ago, and I only realised the other day

I'm changing it in the next few weeks as the engine is slightly noisier.

You'll know if any glow plugs are bad, as the engine will grumble and shake on startup.

#4 12-13-2006, 08:12 PM

It sure sounds like nailing from your description (like someone hitting metal with a hammer?). They do tend to nail more when the are cold, and if the sound goes away it's not likely to be a mechanical problem. A bad, or weak, glow plug can contribute to nailing after a cold start. My 617 has had a weak GP for a couple of weeks (I was out of town and I replaced it yesterday). It would start a little rough, run on 4 of 5 for a couple of seconds, than nail for about 10 or 15 more seconds until that cylinder got up to temperature. Replacing the GP fixed the problem.

TMAllison · #5 12-13-2006, 10:44 PM

My commute is 110 miles. It's bad enough, I feel for you but, at least like me you get to drive a comfy car......

I beleive from your post that perhaps you didnt glow long enough before starting up?

If that were the case, and living in a cold climate as you do, that could cause the knocking/nailing you described.

e300D97 · #6 12-14-2006, 08:59 AM

JNC,

It does sound like you didnt wait out the whole glow stage. Mine will do that also if I jump the gun and dont wait for the glowplug to go out. Just curious where did you pick your 99 up from? Dealer? Private party? I am south of you in York County PA. You definately have a long commute.. Hopefully that was 134 miles roundtrip.

mobetta · #7 12-14-2006, 11:13 PM

sounds like a cold diesel. what were the temps? car inside or out?

jnc19610 · #8 12-15-2006, 09:41 AM

Thanks for the replies......

It hasn't been really cold in PA, maybe 40 degrees. The noise has continued for a few days. I'm a little leary of removing the glowplugs myself on this E300, so I'm going to let an indy look at it.

I'm pretty sure its just a slow or incomplete glow or one injector is messed up. It was going away after a few seconds. I just don't like that hammering / clanking sound.

Today, I double glowed, and it started rough. Clankinging, blowing some blue smoke. It still has a clank here and there. Today it was still noisy and rought after 15 seconds, I'm thinking now it's an injector.

Rather than guess, I'm going to let a tech tell me, and have him look over a few other things while he has it.

Alberta Luthier · #9 12-15-2006, 10:29 AM

Lots of us noobs are sort of wondering what 'nailing' sounds like, so I for one will appreciate it, if you get back to us all with how this gets resolved.
Thanx Alberta Luthier

jnc19610 · #10 12-18-2006, 03:04 PM

Just posting some news as I got it...... I had what I thought was a nailing sound, so I took the car to a tech, being a little iffy about what was wrong.....He said it was nailing an injector, coulnd't really tell which one. So he ran some diesel purge thru (he described it as extremmly strong cleaner) He says it sounds better, but wants to hear it in the morning when it's cold. So... standing by.

I would best describe this noise as the loudest 'pinging' you've ever heard, except it happens at idle. To me it sounded like a random 'hammer' hitting the engine. It was 'centered' on one injector, meaning it was one cylinder, but didn't nail every time. The car also had a 'fat' mixture smell (you could smell fuel) and overall, just didn't seem so happy compared to 20K miles ago.

Now I"m wondering how often I"ll have to do this. I have a 134 mile commute, I get to zip down the highway. The last thing I would have thought is of carboning up an injector with that drive pattern.

More news when I get the car back.

DieselAddict · #11 12-18-2006, 03:56 PM

What you describe is pretty common with indirect-injection diesels, especially in cold weather. It's really nothing to worry about. With the engine cold, you're getting an ignition delay which causes the knocking until the glow plugs fully kick in (if you didn't wait long enough) which reduces the delay and the knocking. If you let the cold engine idle for a couple minutes the knocking will probably return as the glow plugs turn off and cool down, but then as the engine warms up the knocking will subside again. I would just test each glow plugs with an ohm-meter (do a search on this) and just be sure not to start the engine cold until the glow light goes out.