Does this sound like bent rods? (Video) - Page 7 - PeachParts Mercedes-Benz Forum

gsxr · #91 01-20-2009, 10:39 PM

Quote:

Originally Posted by pdrayton

Now I am rethinking the option of the cracked pre-chamber route. But how would a bad prechamber, or a bad head gasket explain why it runs great on veg oil/biodiesel?

Different cetane properties. The veg/bio may ignite more easily than #2. Time to check out that prechamber, since you already did a compression test.

pdrayton · #92 01-21-2009, 05:22 PM

Took out the prechamber and gave it the full inspection.

No obvious cracks or problems except some sort of deposit at the very bottom inside the chamber with the small holes. Looked like a burnt insect, but might have been rust or carbon. I cleaned it out.

Anyway, put it all back and the car was still missing and smoking. So I figured screw it, let's italian tune up the thing and see if it clears out. So I hammered it around my neighborhood (safely), and now it is running fine except for a knocking/nailing sound. No smoking, no missing/rough idle.

Sheesh. I'll have to test it again tomorrow from cold and see what happens. But it seems it is OK except for the nailing/knocking which kinda bothers me because it is a new nozzle and the injector is switched from cylinder 2.

So it is highly unlikely to be the injector. I'm wondering if there is any possible funkiness with the IP that could cause this sort of situation...

Or is it still a possible bad head gasket?

Sidebar: there was black oilyness in the injector 1 that I removed when I took the PC out.

No more steamy goodness, just who bob, what pants?

Random quote day.

Thanks for hanging with me on this one gents.

pdrayton · #93 01-27-2009, 08:50 AM

Summary:

Swapped out injectors - problem remained

Cleaned and reseated PC and the rough idle is 99% gone (it does it a little every now and then, not much, then goes away after revving)

The problem is definately in Cylinder 1 (all noises and smoking go away when fuel supply stopped to that cylinder)

Car is running great except for a knocking/nailing sound at idle. It is the nailing sound in the original video here Just ignore the rough idle and smoking, that is gone since I cleaned the PC.

Question is, could a bad PC make the knocking nailing sound? Or is it more likely to be a bad valve or bearing, or even a bent rod (unlikely becuase of compression?) Perhaps it is time for another new PC. Seems weird since cyliinder 1 is the one with the new PC (1 year old).

Is it bad to drive it like this? It only knocks/nails at idle. It sounds like a sowing machine above 1500 rpm, it's so smooth and has good power.

gsxr · #94 01-28-2009, 07:04 PM

If the prechamber appears ok from a visual inspection (when removed from the head), it's fine. When they fail, the tip blows off, or the spherical pin inside vanishes. If it's good, it can't be the source of the knocking/nailing. That takes you back to compression, injector/nozzle, or injection pump...

pdrayton · #95 01-28-2009, 07:22 PM

PC looked fine - had the ball in position and looking like the other PC I had, no other visible problems.

Compression is 24 Bar warm (60C - that's as quick as I could do the test), same as all the other cylinders. All cylinders are within 2 bar of each other.

Injector and nozzle were swapped out so that can't be the issue.

Injection pump? How do I test that?

Could it not be a bad valve? Or a bad head gasket at cylinder 1? I'm out of my depth here.

gsxr · #96 01-29-2009, 02:06 PM

Quote:

Originally Posted by pdrayton

Compression is 24 Bar warm (60C - that's as quick as I could do the test), same as all the other cylinders. All cylinders are within 2 bar of each other.

Injector and nozzle were swapped out so that can't be the issue.

Injection pump? How do I test that?

Could it not be a bad valve? Or a bad head gasket at cylinder 1? I'm out of my depth here.

Compression numbers are a bit low, especially at sea level. But if all cylinders are around 24 bar, that's acceptable. Could be the gauge reads low. I'm assuming chain stretch is within limits. A bad valve is possible but not likely, I'd expect a valve problem to show up on the compression test. Same with the head gasket. After eliminating everything else, the injection pump is last on the list... no way to check it though, it gets rebuilt, or swapped with a known good used one. If you're lucky, you might find a local Bosch shop that will put it on the test stand and just check it out, without doing a rebuild. Most don't want to do that though.

pdrayton · #97 01-29-2009, 03:49 PM

Timing chain is 4 deg. Possibly 3, max 5.

Thanks for the continuing help GSXR.

I'm residually suspicious of the PC, considering the idle improved when I cleaned and reseated it. Anyway, what do I know...

I'm ok driving it as is - just clacks at idle. Is it damaging anything to drive it with a bad IP? And what does that mean 'bad IP'? If it's the timing that is off, then I guess that is a bad thing. The only other thing could be low pressure, and I don't see how that would make it clack.

Yep, there's always one more question...

gsxr · #98 01-29-2009, 07:39 PM

Quote:

Originally Posted by pdrayton

Timing chain is 4 deg. Possibly 3, max 5. I'm residually suspicious of the PC, considering the idle improved when I cleaned and reseated it. Anyway, what do I know...

I'm ok driving it as is - just clacks at idle. Is it damaging anything to drive it with a bad IP? And what does that mean 'bad IP'? If it's the timing that is off, then I guess that is a bad thing. The only other thing could be low pressure, and I don't see how that would make it clack.

Timing chain sounds fine... at the limit, but that would not cause what you describe. "Bad IP" means the pump is not delivering equal amount of fuel to each cylinder and/or the pressure is off, bad delivery valve, etc. Not likely, but IP's aren't bulletproof. You could try swapping around a couple of prechambers if it would make you feel better. The more things you eliminate, the fewer items remain. With good compression, good injectors, good prechambers, etc... the IP is looking more and more suspicious!

pdrayton · #99 02-28-2009, 12:02 PM

I was driving the car yesterday and noticed it gives a big shot of soot at WOT. Made me start thinking perhaps my previous adjustment of the ALDA has something to do with it, and perhaps it being in the water screwed something up.

However, the noise being linked to cylinder 1 does suggest something else, but perhaps it wouldn't be a big deal if the ALDA was fixed (if it is indeed screwed)

So, the question is, how do I adjust the ALDA back to stock?

gsxr · #**100** 02-28-2009, 02:54 PM

I'm assuming you mean it's smoking when you mash the throttle off-idle, correct? You should adjust the ALDA as lean as possible, but so there is no power loss when leaving a dead stop. This may cause a slight puff of smoke when leaving a stop but it shouldn't belch a cloud.

Now if you mean there is smoke at WOT at high RPM, that's different... ALDA adjustment won't do squat, there is far more air than fuel available at WOT on a good running engine. If you are getting smoke at high RPM / WOT you either have an air restriction, or something screwy with the fueling, or a weak cylinder (which I think you ruled out already), etc, etc...

pdrayton · #**101** 02-28-2009, 04:49 PM

Not sure what you mean "mash the throttle off-idle,".

When I'm at a stop and do WOT, it smokes when the revs get high. Like an Italian tune-up with lots of soot. More than the usual burnout that goes away, seems to come right back. Like there's too much fuel and it's not getting burnt.

gsxr · #**102** 03-01-2009, 11:05 AM

Quote:

Originally Posted by pdrayton

Not sure what you mean "mash the throttle off-idle,".

You're sitting at a stop, at idle. You stand on the throttle. You are at WOT, but the revs are approx 2000rpm for a few seconds until the car starts moving, and the revs begin to increase. If it's billowing smoke for the few seconds from about 0-15mph, the ALDA is adjusted too rich. It should be a puff of smoke (or none).

Quote:

Originally Posted by pdrayton

When I'm at a stop and do WOT, it smokes when the revs get high. Like an Italian tune-up with lots of soot. More than the usual burnout that goes away, seems to come right back. Like there's too much fuel and it's not getting burnt.

When the revs get high, you're no longer at a stop, you're probably going at least 25-30mph and revs would be at 4000-5000rpm. If it's smoking at WOT at high RPM, something is wrong... the smoke should lessen with each full-throttle blast, like an Italian tune-up. If not, you need to figure out what's going on. It's either too much fuel or not enough air (or perhaps something weird happening with the EGR).

pdrayton · #**103** 03-02-2009, 08:16 AM

Thanks for the clarification. Yes, it blows a little puff of smoke at WOT take off from a stop, then at 4000 before it changes gears there is a blow of smoke. It is much less now that I have done it a few times. I think my wife babies this car, even though I repeatedly tell her to give it heck every now and then. I took it for a ride again yesterday and gave it a lot of heck and I couldn't get it to billow at high revs.

I pulled the codes after that ride and got 5, 8 and 15 which are:

5: Y31/1 vac transducer or exhaust control loop

8: Coolant Temperature Sensor (haven't had this code before)

15: Charge Pressure control y31/5

That frigging rat's nest is back to haunt me! It was fine for a good while, now on the fritz. Even so, that wouldn't be causing clacking on cylinder 1 would it? Perhaps it is, who knows. I'm about ready to drive this thing into a lake again....

Cleared the codes, but the egr stopped working again after a bit. I'll pull some of those pieces from my other W124 with the rat's nest removed and put them in and see what happens. Doubtful that the cyl 1 issue is related, but have to remove this possible cause.

Thanks for the support and input.

gsxr · #**104** 03-02-2009, 11:23 AM

The smoke may just be from the light driving... if it lessens with each WOT run, that sounds pretty normal.

About the codes... sheesh, I think it's time to do the conversion to a pressure-operated wastegate so you can eliminate computer control (and EGR) permanently! I'm pretty sure I mentioned this previously, but if not, click here for the thread with details. Total cost is <$100.

pdrayton · #**105** 03-02-2009, 12:01 PM

Yes, I did that conversion on my other 92 300D. It's the one I drive, and I love it. HOwever, the single point of failure (boost tube) and the fact that it is not fail-safe worries when when putting it on my wife's car. She's a driver, she'll keep going until the car breaks down, f you know what I mean!