1987 300SDL with Nailing? - PeachParts Mercedes-Benz Forum

Kincaidj · #1 08-07-2013, 11:40 PM

Hello,

I am a new member who joined after I purchased a 1987 300SDL with some issues. This board has been immensely helpful in sorting out some of the issues such as a hard shifting transmission and AC blowing out the defrost.

Turns out, there was zero vacuum which was a gummed up nipple at the vacuum pump. Now there is vacuum and "lucky me" it shifts great and all my climate controls work properly.

Now for the real problem, tap tap bang bang that sounds to me like the #2 and possibly #3 injectors. It is driving me insane especially since it sounds so bad and yet the car runs awesome. I think I hear two different noises. One is a more of a bang possibly hard nailing and the other is more of a light tap.

I tried to include a YouTube video, hopefully you can see and hear it. This was my first try with an Ipad and YouTube.

Mercedes 300sdl- Noise in OM603 - YouTube

Here's what I know or don't.

142,000 miles
PO didn't have good records
#14 Head
The crappy orginal Vacuum Pump
Timing chain pretty sure is original
Injector nozzles are Bosios but don't know if they were properly popped and balanced
Starts right up but loud tap tap at startup with stumbling and a good amount of blue smoke
After a little warmup, stumbling goes away smoke diminishes taps continue
RPMs over 1200, banging noise quiets but taps continue
The most bazaar thing is going downhill, with a little engine drag and before it up shifts, it's as quiet as a mouse fart.

Any help trying to diagnose this would be very appreciated.

giff · #2 08-08-2013, 07:47 AM

My 603 was noisier than I would have liked when I got it. I did injector cleaner in the fuel and changed oil to full synthetic. Synthetic oil help quell the noise and injector cleaner helped me find all the leaks (which caused me to have to replace all my injector return lines).

Hope this helps....

Kincaidj · #3 08-08-2013, 11:46 AM

I should have added that I did the diesel purge and its amazing how quiet it was while the purge was burned. Being a noob to diesels thought I had this problem licked but sadly nope.

Even did a series of Italian tuneups here in Estes Park whre I live at 7600ft elevation. The car runs amazingly fast even at high elevation and got it to blow lots of black smoke but that could be Alda and altitude.

Then did MM oil in crankcase, and ran it hard then changed th oil to Rotella T and put a Mann filtr in. No real change in noise.

At a dealer, had them change the belt tensioner, shocks, motor mounts and transmission mount. That helped a rattle and shake but not the noise I described.

Next, I think I need to send the injectors off to be popped and balanced. Need to changed the vacuum pump and look at timing chain and guides I guess.

tjts1 · #4 08-08-2013, 12:57 PM

Is it leaking fuel from the IP near the delivery valves?

werminghausen · #5 08-08-2013, 01:48 PM

That noise is 'normal'. No worries. At idle sometimes there is an additional ticking noise from the lifters at my SDL. My engine has 350K miles on the clock but it was never any quieter. At idle a Mercedes diesel sounds noisy. It is what it is.
Martin

Kincaidj · #6 08-09-2013, 11:21 AM

Quote:

Originally Posted by tjts1

Is it leaking fuel from the IP near the delivery valves?

I don't see any leaking at the delivery valves. This knocking/nailing sounds much worse in person than the video sounds. I'm going to a better one tonight and post it.

Not scientific but the worst noise is at injectors 2 and 3. If I listen closely to the rear of the motor it's more of industrial sewing machine noise.

scottmcphee · #7 08-09-2013, 12:36 PM

Thoughts:

Do things improve on a fully warmed engine? I couldn't see the temp gauge in your video you flashed by pretty quickly after starting. Personally I want a little nailing on a cold start, that should quieten down once warm. It's more of a timing advancement indicator for my preferences.

Nailing is worst at cold engine. Crack the injector nut on the suspect nailing injector, when things are cold, does it quieten down quite a bit? Adjust pop setting and check spray for that injector. You may as well walk through the line of injectors cracking one nut at a time and determine the contributions of each, as to the smoothness of running and sounds emitted. You're looking for uniformity. You'll need the right size crow foot socket for this job, to make it real easy. (17mm?)

If running a purge fluid (transmission fluid) on a short tube looping under the hood changes sounds dramatically and things quieten down... your timing might be too advanced. You can try adjusting (retarding) the injection timing to quieten down on diesel. Do this by tipping the IP away from the head. (check other posts how to loosen 3 nuts and the bolt at the back of the IP, then use adjuster screw to change timing, have a IP front O-ring handy and ready to put on, these crisp up and may break or leak when adjusting timing). If you then drive and have a dog, you've retarded too much: advance back and you'll get more sound, but more pull too. There's a sweet spot in this range that will be right for you and your engine's overall condition.

Any "double frequency" sounds are associated with things turning at crank speed, things that sound half as often as that are valve train related (tappets, etc.). Valve train sounds are also "lighter" sounding.

A really worn chain makes it hard to get the right sounds out of the engine, no matter how much you advance or retard timing. Check stretch, various methods documented in other threads. When the chain is newer everything is just more harmonious and less "random" relationship sounding. Hard to explain but you'll know when you hear it. Oh, and the amount of grey smoke on colder engines can tell you a bit about chain stretch too. New chain for me made all the grey smoke go away on my car at idle, even when warm. Now I just blow black (when I want to) using the pedal - an no ALDA!

If no matter what you do with an injector on a particular cylinder appears to have any effect, swapping etc, and problem stays with the cylinder... you could have low (maybe zero) compression on that pot. Let it be.

Check for exhaust leaks or cracks in gasket or manifold around a particular cylinder. These sounds can fool you into thinking something is wrong on the injector side. Nope.

Get a mechanics stethoscope, and poke around the suspect injector, comparing to neighbours. This is a cheap and easy way to find injector issues. You can hear the high pitch "ping" of the pintle reseating after each firing. If you're not too old. Again, looking for uniformity across the line of cylinders.

...

that's all I can think of now

jay_bob · #8 08-09-2013, 02:25 PM

All good advice except the injector nuts are 14 mm not 17 mm.

sixto · #9 08-09-2013, 05:08 PM

Make sure all the injector lines are clamped along the way. They can make noise when free to bump into each other. Unrestrained contact can lead to wear and line failure.

Sixto
87 300D

Kincaidj · #10 08-11-2013, 02:10 AM

I've got a new video of my 300SDL stone cold. It's always much louder when cold.

I hear at least two different noises. The loudest is a distinct hammer on steel bang at approx CYL#2 that's very predictable and doesn't change except when it warms up and gets a bit better.

The other is less rythymic and random, kind of like when you shake the balls in a paint can. What scares me the most is if either the chain is stretched and about to go or the original vacuum pump has let something loose.

Although this sounds awfull, at 1000 RPM and above the sounds are nearly gone and the cars runs awesome. I have no problem running with anyone here at 7500ft except I have to watch my temp closely.

No evidence of coolant loss and burns almost no oil.

300SDL Stone Cold - YouTube

Brian Carlton · #11 08-11-2013, 11:53 AM

Quote:

Originally Posted by Kincaidj

I've got a new video of my 300SDL stone cold. It's always much louder when cold.

I hear at least two different noises. The loudest is a distinct hammer on steel bang at approx CYL#2 that's very predictable and doesn't change except when it warms up and gets a bit better.

The other is less rythymic and random, kind of like when you shake the balls in a paint can. What scares me the most is if either the chain is stretched and about to go or the original vacuum pump has let something loose.

Although this sounds awfull, at 1000 RPM and above the sounds are nearly gone and the cars runs awesome. I have no problem running with anyone here at 7500ft except I have to watch my temp closely.

No evidence of coolant loss and burns almost no oil.

300SDL Stone Cold - YouTube

It does have a bit more noise than most. However, said noise when cold and below 1500 rpm isn't anything to be concerned about. You can only hear it when outside the vehicle. Once you drive it, it becomes a non-issue.

You can spend a bunch of money on injectors and prechambers in an attempt to quiet it down somewhat, but no 603 will ever completely eliminate that noise when cold below 1500 rpm.

When all the hardware is in good condition, the noise largely disappears when fully warm.

Kincaidj · #12 08-11-2013, 12:25 PM

I really appreciate all the comments and advice. After reading lots of related posts here, I do understand that the 603 can be noisy.

Right now, I'm not going to change the #14 head unless it gives me a real reason to. But, I am going to follow some advice from Scott who gave me some very detailed things to consider and follow up on. I really don't have a baseline of known maintenance like the chain and injectors.

I really want to change the vacuum pump to avoid a disaster, check for chain stretch and get my injectors balanced then timing

I guess the most helpful things to ask are: Who can I send my injectors with Bosios to get balanced. I live in Colorado but have ties to North Carolina.

And, if changing the vacuum pump is it also the best time to check chain stretch since its pulled.

Thank you all for you input and if you have other thoughts, let her rip.

vollpreuss · #13 08-11-2013, 12:53 PM

I've been tinkering with an 87 300SDL that is a lot like yours on start up so I am interested in this thread. The SDL smokes quite a bit on start up and an intermittent loud metallic tapping sound. The SDL has 254K on it and I think it has the original injectors on it based on the service records that did come along with the car. I am considering the injector rebuild route myself.

One of the local members in Chicago has used Greazzer on this board for injector service. You may want to check that out. Here's the testimonial.

http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/341985-word-about-greazzer.html

sixto · #14 08-11-2013, 01:22 PM

Eyeballing chain stretch and setting IP timing by hand requires removing the valve cover which requires removing the crossover pipe. The precise method of dealing with the chain requires setting a dial gauge on the #1 intake(?) cam lobe or lifter. I don't think even MB dealerships do this despite details in the FSM. This level of precision requires confidence that the adjustable TDC indicator is spot on. Either trust it of pull the #1 prechamber to set a dial gauge on the piston crown. Eyeballing is very common practice. FWIW, I don't subscribe to a 603 chain having a service life any shorter than, say, the intake manifold if you keep the oil fresh and clean.

Messing with the chain and timing doesn't require removing the vacuum pump. Conversely, replacing the vacuum pump doesn't facilitate any aspect of chain work. Inspect the belt tensioner components while the belt is off to replace the vacuum pump.

Sixto
87 300D