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1997 Mercedes 600 Coupe & 1995 500 Coupe, 2004 Yamaha R1 200hp 360 pounds
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Discussion Starter #1
Was driving the 600 all day in 100 degree temperature (even raced a BMW earlier in the day and got up to 150 or so). Car was smooth as butter ALL DAY. Was driving up the hill to my home at night and heard this loud BOOM and popping noise. No warning lights no guages lit no overheating. I pulled the car to the side as it kept popping. I turned the motor off and checked to see if it was a flat or something i hit. No signes. I was like a block away from my house so I thought Id try and get the car at least to my garage. Turned it back on, she started right up but LOUD POPPING the whole way. A little loss in power but not much but it was LOUD. Got the car to the garage and opened the hood and checked the motor. There is a WHITE straw looking wire (actually several) where the wire harness is that is literally in pieces. I can literally break this wire apart as its all over the top of the motor. Before I have it towed has someone else experienced this? Is it the whole wire harness or maybe a vaccum line? All guages work, mirrors, windows, stereo, lights everything fine so I am assuming I didnt blow my motor, but I actually have never seen this white wire before. I will be checking maybe each of the plugs to see if maybe one blew out but this straw looking wire is DEFINATE strange since ive never seen them before. Any idea before I spend a grip fixing her would be appreciated :thumbsup:
 

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2000 C280, 2006 E350, 1993 400E, 2007 SLK55 AMG, 1994 S500, 2008 E320 Bluetec
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685 Posts
At first I was thinking that you have a problem with your exhaust somewhere. But now, with the harness into play... could it just be V12 backfire? You didn't notice a rough engine after the initial boom, did you?
 

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1997 Mercedes 600 Coupe & 1995 500 Coupe, 2004 Yamaha R1 200hp 360 pounds
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Discussion Starter #6
been out of town ill get pics tonight....i thought it was the exhaust too but I checked and no holes...but these white straw looking wires on top of the engine must have something to do with it...car is still somewhat smooth but it sounds like a shot gun :(
 

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Current 1992 - 500SEL, W124 - 1989 230E (sold)
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Sounds like you are running bit rich and unburned fuel is poping in exhaust, not sure if you crumbling harness has anything to do with it but ts more than likely.
ANy chance of photos of those "straw wires" just to see if they are original or someone already tryed replacing some....
 

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1993 300SEL (Sold) 2007 X5
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If it is the harness this would be the first instance of a post 1996 W140 with harness problems. Perhaps the extra heat in the 600's engine bay is to blame?
 

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W639 Vito 110 CDI; Ponton 220S; VW Phaeton V10 tdi; 1995 S500 ex diplomatic car (gone)
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574 Posts
Impossible to say on the information given.

My guess is a blown out plug and a shredded HT lead.
 

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1997 Mercedes 600 Coupe & 1995 500 Coupe, 2004 Yamaha R1 200hp 360 pounds
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1,146 Posts
Discussion Starter #11
I started it up today and feel A LOT of air shooting up from the back of the engine (opposite the fan) but it idles fine. Must be a vaccum leak. Ill post pics tomorrow and hopefully someone can advise b4 I bring her in to the stealer
 

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1997 S600 (sold)
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I started it up today and feel A LOT of air shooting up from the back of the engine (opposite the fan) but it idles fine. Must be a vaccum leak. Ill post pics tomorrow and hopefully someone can advise b4 I bring her in to the stealer
Nah, you must have an exhaust breach. A vacuum leak is just that, vacuum. It sucks, not blows. And, your car will not idle smooth with a major vacuum leak. I would not take it to a dealer. Take it to an exhaust specialist, one who can do custom fabrication because you may need a new flange built. It'll likely be repairable by the right person. If the problem is with the manifold, it'll be a bigger pain to remove the manifold for work. If it's with the catalytic converter pipe, new ones are around $1500 each. As was explained to me by an exhaust fabricator, he could not legally reinstall the catalyst pipes on my car that he had welded new flanges onto. No modification is allowed to the catalyst pipes even ones that have nothing to do with the catalyst by California law. No big deal as I had brought them to him off the car and expected to put them back in myself.

Or maybe you just lost a couple of flange bolts and the pipes came disconnected. That would be a nice surprise. A couple new bolts and you're good to go.

Just re-read your original post where you mention the initial boom. Must have been an exhaust backfire that blew a hole in the exhaust.

Brett
 

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1997 Mercedes 600 Coupe & 1995 500 Coupe, 2004 Yamaha R1 200hp 360 pounds
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Discussion Starter #13
Nah, you must have an exhaust breach. A vacuum leak is just that, vacuum. It sucks, not blows. And, your car will not idle smooth with a major vacuum leak. I would not take it to a dealer. Take it to an exhaust specialist, one who can do custom fabrication because you may need a new flange built. It'll likely be repairable by the right person. If the problem is with the manifold, it'll be a bigger pain to remove the manifold for work. If it's with the catalytic converter pipe, new ones are around $1500 each. As was explained to me by an exhaust fabricator, he could not legally reinstall the catalyst pipes on my car that he had welded new flanges onto. No modification is allowed to the catalyst pipes even ones that have nothing to do with the catalyst by California law. No big deal as I had brought them to him off the car and expected to put them back in myself.

Or maybe you just lost a couple of flange bolts and the pipes came disconnected. That would be a nice surprise. A couple new bolts and you're good to go.

Just re-read your original post where you mention the initial boom. Must have been an exhaust backfire that blew a hole in the exhaust.

Brett
Well when I start the car it sounds like a steamer locomotive train. It runs and is smooth but sounds AWEFUL. Air is shooting out like a steamer. I hope what you are saying is correct. My girl has my digi camera and I want to show you guys this white straw looking wires that are breaking in pieces that are in between the manifold next to the spark plugs. I wonder if that has something to do with it. I will do my best to get pics asap. I hate just looking at her in the garage. I wanna drive her again :thumbsup:
 

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1993 300SEL (Sold) 2007 X5
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Well when I start the car it sounds like a steamer locomotive train. It runs and is smooth but sounds AWEFUL. Air is shooting out like a steamer. I hope what you are saying is correct. My girl has my digi camera and I want to show you guys this white straw looking wires that are breaking in pieces that are in between the manifold next to the spark plugs. I wonder if that has something to do with it. I will do my best to get pics asap. I hate just looking at her in the garage. I wanna drive her again :thumbsup:
Are you sure it's wires and not some kind of insulation?
 

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Current 1992 - 500SEL, W124 - 1989 230E (sold)
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PHOTO PLZ :) also point out where is the "air" comming from on the photo....
 

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1997 Mercedes 600 Coupe & 1995 500 Coupe, 2004 Yamaha R1 200hp 360 pounds
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1,146 Posts
Discussion Starter #17 (Edited)
Also I pulled one of the plugs (I mean coil) where it was making the most noise and here is what I found. What is this part called and is it expensive? Thanks for all the help gentlmen. I know this is the problem and I am glad that it wasnt the motor blown.
 

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1997 S600 (sold)
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Also I pulled one of the plugs where it was making the most noise and here is what I found. What is this part called and is it expensive? Thanks for all the help gentlmen. I know this is the problem and I am glad that it wasnt the motor blown.
OK, not the exhaust then... That's a damaged ignition coil in the 2nd to last picture. Now where is the spark plug? You said you pulled the plug.

The plastic tubes are vacuum hoses.

Brett
 

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1997 Mercedes 600 Coupe & 1995 500 Coupe, 2004 Yamaha R1 200hp 360 pounds
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1,146 Posts
Discussion Starter #19
OK, not the exhaust then... That's a damaged ignition coil in the 2nd to last picture. Now where is the spark plug? You said you pulled the plug.

The plastic tubes are vacuum hoses.

Brett
Sorry I meant I pulled out one of the coils. I havent pulled the plug yet so I dont know its condition. Thank you for telling me it is called the ignition coil. Those vaccume lines, can they be replaced without replacing the harness?
 

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2009 SL65, 1998 CL600 (sold), 1989 560SEL (sold)
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If air is coming out of the spark plug well then the maybe the plug has been damaged. From the condition of the plug wire it does look like something violent occurred down there. That spark plug is a bit difficult to get too. You should be able to shine a flashlight down the hole to see what's going on. You might want to hand it over to a mechanic at this point.
 
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