Mercedes 300SDL Engine Knocking. - Page 7 - PeachParts Mercedes-Benz Forum

86-300sdl · #91 05-31-2017, 09:44 PM

Quote:

Originally Posted by Father Of Giants

Once the fuel line brackets arrive i'll take it for a spin on the highway.

While waiting for the clips....Go drive it... & have fun. You'll be ok with out the clips for a short while. Just don't go put a couple of thousand miles on it. Its more a wear issue at the fuel line tips that is what some refer to as cracking the line.

I listened to your video clip...sounds pretty good. Thinking you just need to run the thing in after your refreshed component work.

Put a 1/2 qt of 2 cycle in the fuel. Maybe even with some cetane boost for good measure, although the 2 cycle should do that. Then go flog it, several times (LEO permitting lol). Kind of an Elvis Costello "cruel to be kind for all the right reasons" thing. I almost hate doing it, but my sdl loves it.

Father Of Giants · #92 06-01-2017, 09:20 AM

Quote:

Originally Posted by 86-300sdl

While waiting for the clips....Go drive it... & have fun. You'll be ok with out the clips for a short while. Just don't go put a couple of thousand miles on it. Its more a wear issue at the fuel line tips that is what some refer to as cracking the line.

I listened to your video clip...sounds pretty good. Thinking you just need to run the thing in after your refreshed component work.

Put a 1/2 qt of 2 cycle in the fuel. Maybe even with some cetane boost for good measure, although the 2 cycle should do that. Then go flog it, several times (LEO permitting lol). Kind of an Elvis Costello "cruel to be kind for all the right reasons" thing. I almost hate doing it, but my sdl loves it.

Alrighty.

I'll do just that.

Note to self:
15 milileters of diesel lubricating additive per gallon
4 milileters of cetane booster per gallon

Father Of Giants · #93 06-03-2017, 07:56 AM

Ok so I test drove the car, as it warmed up, things just took a turn for the worst.

Just before I got home, I noticed a change in engine sound. It was this very loud knocking sound. I think it's a rod. I checked my oil level a few days ago and the car wasn't even driven. Also, to make matters worse, cylinder #6 is dead, it doesn't react at all to cracking, as a matter of fact the car runs smoother with #6 gone. It also doesn't smoke with #6 cracked.

Here is video.

https://www.youtube.com/watch?v=WqLeQhujiyk

Father Of Giants · #94 06-03-2017, 09:29 AM

Update: Switched injectors 1 and 6 and the weird sound went away. Injectors 1 and 6 had some black crud on them, but injector 6 was worse. Still knocks as usual, but like as previously stated, I'll have some diesel lubricant and cetane booster to take care of that. Took it for a spin and the knocking and smoke goes away around 25+mph.

Once I put the hard line brackets up there and make my witche's potion of lubricity and cetane boost, I'm gonna drive the snot of it and give it a good old Italian tune up. Should have this purring by then.

86-300sdl · #95 06-03-2017, 09:38 AM

[QUOTE=

Once I put the hard line brackets up there and make my witche's potion of lubricity and cetane boost, I'm gonna drive the snot of it and give it a good old Italian tune up. Should have this purring by then.[/QUOTE]

^That-a boy...

Listened to the your new video...don't hear a rod knock, just diesel knock. Give it some miles too. Like maybe a 100 mile run at around 3k rpm.

Remember that the 2 stroke may produce a little blue smoke and that's just fine.

Father Of Giants · #96 06-03-2017, 09:52 AM

Quote:

Originally Posted by 86-300sdl

^That-a boy...

Listened to the your new video...don't hear a rod knock, just diesel knock. Give it some miles too. Like maybe a 100 mile run at around 3k rpm.

Remember that the 2 stroke may produce a little blue smoke and that's just fine.

Ok. Also, the injector knock got MUCH quieter after going WOT about three times, smokes a lot less too.

Looks like I just have to just drive the thing.

Diseasel300 · #97 06-03-2017, 10:09 AM

LOUD injector knock. I'd suspect you either have an injector that's piddling or you have a DV that isn't sealing properly. That's way too much for cetane boost or 2SO to take care of, you need to find out what is causing that noise or you may actually wind up with a bent rod because of it. Depending on the cause, you could be hearing predetonation (which is what it sounds like to my ear), and it's just as destructive, if not moreso, on a diesel as it is in a gas engine.

Father Of Giants · #98 06-03-2017, 10:37 AM

Also the sound in the video is gone after switching injectors.

I'll retorque the delivery vavles for good measure.

Funny thing I've grown to like the sound of it.

Father Of Giants · #99 06-06-2017, 08:13 PM

Put some fppf+8 in the tank and it made the car a little quieter. Car still knocks at low rpms and it disappears at higher revs. Stopped the horrid shaking at idle though.

I guess it'll take some time to drive the car and see if things smooth out.

Heck if the cetane booster + optilub xpd + a good long drive don't stop the knock, I'm just gonna give up and safely ignore it henceforth

I'll report back and see how that goes

Diseasel300 · #**100** 06-06-2017, 08:26 PM

It's an IDI. They're never perfect and I swear they have moods. Mine has an injection knock that comes and goes at idle. Usually by the time the engine is nice and hot it shuts up so I don't worry too much about it. I have traced it down to Cylinder 5, which is one I haven't messed with in the IP. At some point (probably this fall) I'll lap the DV and see if it quits once and for all. Until then, I'm not worried about it.

Father Of Giants · #**101** 06-06-2017, 10:11 PM

Quote:

Originally Posted by Diseasel300

It's an IDI. They're never perfect and I swear they have moods. Mine has an injection knock that comes and goes at idle. Usually by the time the engine is nice and hot it shuts up so I don't worry too much about it. I have traced it down to Cylinder 5, which is one I haven't messed with in the IP. At some point (probably this fall) I'll lap the DV and see if it quits once and for all. Until then, I'm not worried about it.

I think i'm going to get a Leakdown tester and get to the bottom of this. Cylinder #6 doesn't even run at all during cold start. Something is worn out.

Maxbumpo · #**102** 06-07-2017, 09:04 AM

If moving injectors around or using some fuel additive made a difference, this is NOT a compression issue. Focus on injectors and delivery valves, maybe IP timing, maybe insufficient turbo boost.

Diseasel300 · #**103** 06-07-2017, 09:47 AM

^^^x2

You've already had the car running on 6 cylinders and smoothly at that with the diesel purge. That means you have injection issues, likely delivery valve problems or timing as said above.

Father Of Giants · #**104** 06-07-2017, 10:19 AM

Quote:

Originally Posted by Diseasel300

^^^x2

You've already had the car running on 6 cylinders and smoothly at that with the diesel purge. That means you have injection issues, likely delivery valve problems or timing as said above.

Sorry for the mis info. Switching injectors and cetane booster didn't solve it. Still very shaky and Smokey during cold start.

Ok, once the crank is at TDC...say cam timing is off, how do I correct that?

Injection pump timing is an entirely different beast I assume. How do I check and correct that?

One last nagging question, do you know of a good quality leakdown tester and how would I adapt it to the om603.

I need to double check both camshaft and injection timing to be 100% sure.

Father Of Giants · #**105** 06-09-2017, 09:30 PM

After a few runs on the highway, once the car is warm the knocking, smoking and shaking has completely ceased.
However when cold it still has a rough and smokey idle, I can live with that.