Mercedes-Benz Forum banner

1 - 8 of 8 Posts

·
Registered
2002 Silver Arrow SL500
Joined
·
28 Posts
Discussion Starter #1
Hi All,

Have a 2002 SL500 that has recently started to make a slight knocking sound at idle after the car has been running. I only notice it when the top is down and I am pulling into the garage. The slightest of rev's will make the sound go away. It really only appears when the car is at really low speeds or stopped. Just had the engine mounts, water pump, and pulleys replaced three months ago, so I am wondering if this is what started it. It appears to be coming from the passenger side of the vehicle and on the lower end of the engine. Any tips or hints before I take it to my indy?

Thx,
B
 

·
Registered
Departed 1998 SL500 (and the Pano is in Bogota)
Joined
·
11,122 Posts
I would check that engine mount that was recently replaced.
 

·
Registered
2002 Silver Arrow SL500
Joined
·
28 Posts
Discussion Starter #3
I would check that engine mount that was recently replaced.
That's what I was thinking because it does not sound like an engine noise but you never know and my wallet cries every time my beloved Silver Arrow makes a squeak.
 

·
Registered
1999 SL 500 SL-2
Joined
·
170 Posts
1. Checked oil level ?
2. Type of oil ?
3. Last engine oil/filter change ?
4. Does it knock cold, or only warmed up ?
5. Mileage ?
6. Factory engine mounts ?
7. Oil and water temp noted at time this starts ?

Being a 2002, you don't have oil pressure readouts, only oil temperature.

If it was mine, I would not drive it until you can verify source of noise is not low oil pressure.
 

·
Registered
2002 Silver Arrow SL500
Joined
·
28 Posts
Discussion Starter #5
1. Checked oil level ?
2. Type of oil ?
3. Last engine oil/filter change ?
4. Does it knock cold, or only warmed up ?
5. Mileage ?
6. Factory engine mounts ?
7. Oil and water temp noted at time this starts ?

Being a 2002, you don't have oil pressure readouts, only oil temperature.

If it was mine, I would not drive it until you can verify source of noise is not low oil pressure.
1. Oil level is full.
2. Mobil One sythetic, I would have to dig for the weight but it is factory recommended.
3. Oil change was 5K miles ago (good for 10K according to the dealership).
4. Only knocks warmed up.
5. 78K miles on the ODO
6. All factory, all the time.
7. Water temp is ~85C and oil temp is steady where it always is at around 75C.

It is not low oil pressure from what I can tell. Runs and drives like a dream.
 

·
Registered
1999 SL 500 SL-2
Joined
·
170 Posts
If a knock and not a tick (or tap like a lifter), I wouldn't drive it. Motor mounts are not temperature sensitive.

Does the engine visibly shake in synch with the sound?

Does it knock only in gear, or neutral also?

Do you do your own oil changes?

Before taking it to the dealer for a pressure check, you could try a new oil filter and oil. Most likley not going to go away on its own.

I don't think you have really ruled out low oil pressure at idle. It will continue to drive 'like a dream' for a while in this condition, but things will change for the worse, if it is low pressure at idle rpm.

If you have a floor jack, raise the right front on the rubber pad (with plywood pad) under the front of the passenger sill, remove the right front wheel, the lower access engine dust-debri sheild, and check various points with a $10.00 engine stethascope.

Not worth the chance to not know more before continued driving.
 

·
Registered
2002 Silver Arrow SL500
Joined
·
28 Posts
Discussion Starter #7
Somewhat good news. It was the passenger side catalytic converter. It was broken and rattling at low RPMs but only when warmed up. Thanks for your help and advice.
 
1 - 8 of 8 Posts
Top