Rough Idle And Noise
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Junior Member
Joined: Aug 2005
Posts: 35
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From: Oregon
2005 E320 CDI, 2011 ML350 4Matic
Rough Idle And Noise
Just bought an 86 300E and cant seem to get rid of the rough idle. Put new wires, cap, rotor,plugs in. It helped cause the old wire were arcing pretty bad but it still doesnt seem smooth. Its got 201,000 on it. It seems more rough in drive at a stop. also there's a kind of clattering coming from the engine only when its in gear. Sounds almost like a diesel at times and maybe coming from the water pump/power steering pump area but hard to tell exactly. Almost seems to go away in neutral. I got an owners bible with the car and see a deal about the camshaft bearing cap bolts stripping out and causing bad idle. Have'nt had time to pull the valve cover yet but plan to this weekend. Also when i brake fairly hard i notice the shifter lever moves back quite a bit. is this normal or do I have a mount broke or loose somewhere?
any help you can give would be nice. Im a newbie for sure
Pat in Oregon
any help you can give would be nice. Im a newbie for sure
Pat in Oregon
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From: Belfast, N Ireland
93 320CE, 72 280SE 3.5, 55 220A, 05 E280CDI, 88 Mini Mayfair, 90 Peugeot 205GTI, 04 Mini Cooper
Check your engine mounts, they can go hard and give rough idle. Have you checked the timing?
One thing to try: put a mark on the distributor and the block where it is mounted, loosen the hex bolt and then turn the distributor very slightly and see it if improves. Try it in both directions. If it does not improve, move it back to the alignment marks you made and lock it off.
As my dad always says, try the cheapest things first.
One thing to try: put a mark on the distributor and the block where it is mounted, loosen the hex bolt and then turn the distributor very slightly and see it if improves. Try it in both directions. If it does not improve, move it back to the alignment marks you made and lock it off.
As my dad always says, try the cheapest things first.
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Joined: Apr 2005
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From: Northern Cali
W124
I experience a similar symptom. On hot days or when the car is hot it will idle rough when in drive but fully stopped. The oil pressure goes down when this occurs. It would do this even before I got a lower temp. thermostat and fixed my fan switch. This only happens on occation but usually when the outside temp. is fairly high. I used to suspect the water pump but now I've run out of ideas.
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Joined: Apr 2005
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From: Long Beach, Ca
lots of cars
Change your o2 sensor and your temp switch not the one for the fan but the one by the 6th cylinder. Also check that the are no leaks by the idle control valve. If your going to buy spark plugs just go with the bosch supers h8dc not h9dc because it's a hotter plug (feels like *****). Also make sure the throttle cable is adjusted correctly.
use an o2 sensor from a 1990 mustang
use an o2 sensor from a 1990 mustang
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Joined: Sep 2005
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From: Gledale,Ca.
1989 300E
In the other club, one member said that you can't use PLATINUMS ( I'm using NGK's) or I will encounter bigger problems. My 300E used to shake but when I switched to 91 and changed to platinums, it went away. I am confused.
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Mercedes-Benz w124
yea, platinums are bad for these cars ( as ive heard, not tested ) and from what it sounds like, looks like you need engine mounts. it shakes while in drive but not in park ( both at 0 mph? ) at benzworld someone replaced them in like 15 minutes from when i last heard. i think i saw them for $100 a while ago. good luck!
Newbie
Joined: Jul 2005
Posts: 9
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From: Bangalore, India
Mercedes Benz 230e, 124
Rough Idle
Hi,
Have you checked the engine vibration damper that is integrated with crankshaft pully. The crankshaft pully and the vibrationdamper is mounted on rubber which over the years disintigrates causing noise like a diesel motor. The location of the sound does indicate it could be that. and the only way you can inspect it by removing it, and it is eld back by a 19MM nut and can be opened with a deep socket box spanner.
Have you checked the engine vibration damper that is integrated with crankshaft pully. The crankshaft pully and the vibrationdamper is mounted on rubber which over the years disintigrates causing noise like a diesel motor. The location of the sound does indicate it could be that. and the only way you can inspect it by removing it, and it is eld back by a 19MM nut and can be opened with a deep socket box spanner.
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Joined: Sep 2005
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From: Gledale,Ca.
1989 300E
Originally Posted by jettskiman
I put NGK's in it.
Changing the engine mounts will help but you have to find the cause of the rough idle. Even with bad mounts, it should feel smooth and consistent. No intermetent shaking.
Have you done an oil cahange? Switch to synthetic like MOBILE 1. It will clean yor oiling system especially the lifters. It can gum-up and stick and can cause rough idle quality.
One more thing, the noise. You think it's the water pump or something. For you to find out, take the belt out and then start the engine. If the noise disapears, you know where it is coming from or you know where to trouble shoot. DON'T LET THE ENGINE RUN TOO LONG, YOU WILL OVERHEAT THE ENGINE. Run it for half a minute. I think thats long enough. And also, check your oil pressure at normal temp.
Last edited by luvmuzik66; Oct 21, 2005 at 11:38 PM.
Thread Starter
Junior Member
Joined: Aug 2005
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From: Oregon
2005 E320 CDI, 2011 ML350 4Matic
Found the noise!
Originally Posted by Nandgopal
Hi,
Have you checked the engine vibration damper that is integrated with crankshaft pully. The crankshaft pully and the vibrationdamper is mounted on rubber which over the years disintigrates causing noise like a diesel motor. The location of the sound does indicate it could be that. and the only way you can inspect it by removing it, and it is eld back by a 19MM nut and can be opened with a deep socket box spanner.
Have you checked the engine vibration damper that is integrated with crankshaft pully. The crankshaft pully and the vibrationdamper is mounted on rubber which over the years disintigrates causing noise like a diesel motor. The location of the sound does indicate it could be that. and the only way you can inspect it by removing it, and it is eld back by a 19MM nut and can be opened with a deep socket box spanner.
I finally figured out what the rattling noise is on this baby. It is coming from that damper behind the pulley. The rubber bushing thats at the top where its bolted on must be worn out. If I hold some pressure on it at the top it quiets right down! Thanks!
Last edited by jettskiman; Mar 4, 2006 at 11:44 PM.
Thread Starter
Junior Member
Joined: Aug 2005
Posts: 35
Likes: 1
From: Oregon
2005 E320 CDI, 2011 ML350 4Matic
Update on the rough Idle and stuff
I did find that both of the motor mounts were broke on this baby. Probably from the front side collision that it was in before I bought it. They snapped off right where they bolt onto the rubber engine mount. They are quite thin allumium right at that point and are probably made to break in a wreck as part of the energy absorption. I dont know but I got both out of pick a part. the right side was easy to pull and put in but I had the guy pull the left for me out of the yard and put it in myself. After I took the right one out and left the engine blocks up the other one was a little hard to get to out in the wet gravel lot. Got them for 15 bucks a piece though. (20 to take that one out though). Anyway the rattle that I have is coming from that vibration dampener just behind the flywheel. ( Thanks Nadgopal!) Its the little shock looking thing that sits almost vertical. I havent tried to tighten the 10 or 12mm bolt through the top bushing yet but it looks like it might tighten up a bit and quiet down. If not I'll see if I can get one and get the flywheel off and put it on. If I hold some pressure against it, its quiet as a mouse. I still have a very slight miss but I havent put an O2 sensor on yet or replaced the temp sensor by # 6 yet either. My daughter's getting her licence on Tuesday so I'm sure I'll be doing a lot more work on this baby in the months to come. Thanks for all the help everyone. This is a great car and its just a kick in the *** to have and work on.
