I hope anyone can help me resolve an ongoing issue I have with my e300d sounding like a tractor when idling.

Everything sounds great when under load or giving some revs but it's so loud its embarrassing when waiting at lights etc.
The noise is like a steady bang, bang, bang so originally I thought it could have been a really bad diesel knock.
What I've tried so far....
* Delivery seals replaced.
* Injectors removed, stripped down and cleaned.
* Tank filter cleaned and tank removed and cleaned too.
* Neat diesel flush. (I did think this may have made the noise slightly less but in hindsight perhaps it didn't)
* Re routed the fuel line to skip the pre filter as I was getting air into the fuel system from the pre filter. I'm not now but the noise is still present.
* Used some hydraulic valve lifter treatment.
* Several oil changes
* Compression test is good and no blow back noticeable when the intake manifold is off.

Listening with a screwdriver I really can't identify exactly where the noise is coming from and I don't have one particular injector that's noisier than the others.

Any suggestions as to where to look now would be greatly appreciated. I'm getting to my wits end with this noise!!

You mentioned the delivery valve seals being replaced in your information. My 96 E300d engine was a smooth as silk at idle, with no sounds what so ever. My delivery valves started leaking, and I needed to replace them. Some members of the forum stated that it was not necessary to replace the copper crush washers, and that you could just replace the rubber seals. I did the delivery valves that way the first time, torqued them according to the book, and when I started the car, it sounded like a TRACTOR making all kinds of noise that was not there prior to my fix.

I did the delivery valves a second time, only this time replacing the seals and crush washers, torqued them to specks, and the engine was back to normal........no shakes or noise. Good luck!!!

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96 E300d

Are the three belly pans in place? It is definitely louder without them.

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Len
'59 220S Cabriolet-SOLD and living happily in Malta
'83 240D 351,500 miles original owner-SOLD
'88 560SL 41,000 miles - totaled and parted out
https://sites.google.com/site/mercedesstuff/home
'99 E300 turbo 227,500 miles
'03 SLK320 40,000 miles - gave to my daughter
'14 Smart electric coupe 28,500 miles
'14 Smart electric cabriolet 28,500 miles
'15 Smart electric coupe 28,000 miles

The belt tensioner shock can make a lot of noise at idle if it is rattling against the head. At idle use a long screw driver to pry the shock mount away from the engine to see if the noise stops. Watch out for the fan. I quieted mine down by putting a plastic oil plug washer between the shock mount and the head.

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'97 E 300 D

Yeah Pimpernel I did replace the copper washers when I did the delivery seals. Might be worth taking another look and double checking they are torqued correctly. I've tried listening to the injection pump with a screwdriver and I'm not hearing anything major from there or the injectors, or the head or the block for that matter.

Pretty sure the noise isn't coming from the tensioner shocker. It is rattling a little but nothing compared to the knock, knocking I get at idle!

I've tried listening to the injection pump with a screwdriver and I'm not hearing anything major.

I do have the belly pans off so that isn't going to help but I've heard many saying that this engine is pretty smooth and quiet. Guess it would dampen it a bit but I'm pretty sure it's not supposed to be that loud. I'll try putting them back and see if it makes a lot of difference. To be honest if it wasn't for it running so smoothly at higher revs and others saying how smooth the 606 was I'd probably just think it was a noisy diesel and just live with it or try to dampen/sound proof a bit more.

At the moment if I'm at idle or parked people stop and look expecting to see a tank or something!

Don't know whether this is connected or not but I've just changed the auto transmission oil and took the car for a drive. Around 2000 rpm I'm getting a big loss of power and a puff of smoke out the exhaust! Press the accelerator and it drives ok but when I get back to gentle revs it loses power again. you can see the rev counter flutter up and down, the car jerks a little then if you let off the accelerator or put your foot down it drives ok.

I'm presuming that this problem can't be connected with changing the gear oil and that it's more likely connected to my noisy idle problem??

It's like there isn't a complete combustion at around 2000 rpm yet it's ok at lower or higher revs??? I know the compression is good so it's got to be fuel right?

Any idea's? I'm thinking to check the delivery seals again then the injectors. When I took the injectors out for cleaning I didn't pop test them so perhaps that the problem???

Egr gummed up / slow to open and close affecting burn in cylinders .
Also turbo should be giving its all around 2k revs .
Check vacuum actuators .

Thanks for the pointers Murkybenz. Mine is the non turbo. I should have mentioned that I've already checked the actuators and they seem to be opening and closing at the correct revs. I've had all the actuators and the egr off and cleaned them too. I do have a small crack in the EGR tube that connects to the exhaust manifold. I can't seem to find a replacement part for this but think it should weld up ok. I don't think this tube should be causing this new problem I have but I'm open to suggestions otherwise.

I've also cleaned up the intake manifold whilst doing the above.

Perhaps the IP timing is out? anyone know the best way to check that? I guess that would explain the noise only at idle and the loss of power/surging at around 2000 rpm??? Saying that if the IP timing was out it would surely be noisy and surging all the time???

Hold on a minute....
I've found a vacuum line that comes from the bottom one of the vacuum switches (not sure if that's the right name) located below the air filter next to the EGR valve. I've looked online to try and find where this should connect and can't find anything for this model! I've spent a couple of hours searching the engine bay to find anything missing a vacuum pipe and haven't found a thing!! Grrr not sure if this could correct the surging but I'd like to find where it lives non the less.
The vacuum line is about 1.5 meters long which doesn't help as it could go virtually anywhere!!! If I suck on it it closes the air intake. Anyone else with a non turbo 606 want to tell me where the really long vac line (black in colour) from one of the two modules/switches below the air filter beside the EGR valve is supposed to go?
Thanks in advance

There are the two sensors on the side of the air intake filter box which have the same part number. One controls the resonance flaps, and the other controls the egr valve. On my model, 96E300d, those two vacuum pressure transducers also receive a signal from an intake manifold sensor that is located on the left wheel well, and has a small black rubber hose attached to the intake manifold. Then there is the actual throttle position sensor itself located near the drivers side firewall. You mention that you changed out the glow plugs, and that may have required the crossover pipe to be removed. I changed out my plugs, and when I reinstalled the crossover pipe, one of the small wires connected to the resonance flap control broke, and when I went to start the car, I immediately got a code. Those connection plugs are small and it is very easy to damage the wiring. Along with checking the vacuum lines as already suggested, I would also remove each electrical plug, spray it with electronics cleaner, and reinstall it. Hope this helps...

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96 E300d

I also have the 96 e300d! Mine is the left hand drive model but don't suppose that would change things too much. Perhaps mine could have been a 95 build but registered in 96.
My engine appears to be a little different to your description in that I don't have any electrical connections to my cross over pipe. The switch that controls the vacuum to the resonance flaps is located under the cross over pipe on the bottom side of the intake manifold itself. There is a small vacuum pipe from this to the cross over pipe.

Actually it's gonna be easier with a photo. Here you can see in one photo the sensors that are under the air intake filter/next to the EGR. The (Now) short vacuum line (on the bottom) is the one I'd like to find out where it connects??? It was about 1.5 meters long before I took the car out and melted the line on the exhaust manifold!!!
The other photo shows what I think to be the intake manifold sensor which is located in front of the throttle position sensor and connected to the intake manifold by a short length of vacuum line.

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Took the car out again this morning and after flooring the accelerator the surging at around 2k RPM went away and the car drove fine!!

Could the tank strainer have blocked up again? I had this out and cleaned it 2 months ago!

Still sounds like a tractor on idle and I haven't found where the hell the vacuum line from the switch under the air intake filter is supposed to connect too.

If anyone can shed any light on that that would really help. Perhaps I need to start a new thread for that as I don't think it can be connected to the noisy idle problem I originally posted about??

Going to try a diesel flush again to see if that has any effect on the idle noise!

I wonder if air is getting in there. I remember changing fuel filter and some fuel lines on one of those an when it first starts -- it is loud , scary almost. clack clack clack. Definitely would be embarrasing. Does your's have the shut off switch on top of the fuel filter bolt? This was a 1995 with the 606 that had that. The problem was the injectors would bleed down because that shutoff switch leaked air. I replaced it with a regular fuel filter bolt that didn't have the shutoff on it. That fixed the problem.

Sorry that's not gonna help ya much. I'll check my 1997 and look for that vacuum line.

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What Would Rudolph Do?
1975 300D, 1975 240D, 1985 300SD, 1997 300D, 2005 E320 , 2006 Toyota Prius

I mentioned this before, but I didn't see that you have pried the tensioner shock away from the head while idling, to see if that solves your loud idle. Mine only rattled at idle and was very loud until I installed a plastic oil plug washer to keep the shock away from the head.

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'97 E 300 D

Check this link, this looks similar to my system:

Mercedes VACUUM SYSTEM 210

In my '97 one of the black rubber lines turns into a thin, smooth, white nylon line running from one of those transducers around the back of the engine into the vac pump I believe. If any of those little rubber elbows or connectors are old or cracked, you will have a leak. I had to replace some of mine for things to run well. The transducers themselves can leak - all the time, or only when energized. In addition, if you haven't done the EGR bypass yet, you should do so - my car ran better immediately.

I've discovered that when things are running well, you should get a vacuum of about -20 inches Hg as measured with a Mityvac at the EGR. If you are getting notably less I would start looking for leaks. Then again, if you have leaks you should see a code when the flaps/EGR aren't working right.

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Charlie

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'66 VW 1300 96K miles
'97 E300D 239K miles
'85 300D 203K miles (sold Sep 2012)