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MB E420T
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Discussion Starter · #1 ·
Dear Forum,

i find many DIY write ups with pics on spark plug changes, but none for the E420 V8 engine.

from experience, there are usually some differences between the V6 and the V8 engine, therefore it would be extremely helpful if somebody could share me a DIY-tutorial (with pics) on how to do a full spark plug change on the V8.

not sure, but my guess would be that the E430 engine should be a similar procedure.
Any hints and
show of tools needed is also most appreciated.
thanks guys!
 

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06 CLS500, Boeing-737, 04 Tahoe LT, 04 Infiniti G35 Sedan
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Its real simple and really doesnt need photo's. There nothing to it. Start by removing the intake cover, six release clamps on the air filter box then gently lift the cover off. Then remove the black valve plastic covers. Not sure what type/size those are but they look like a torque nut. I think I used a standard socket. Kept trying one until it fit snug. Then under the black cover you'll see the four coils each with a wire bundle that has a clamp. Remove them. (You can do the clamps one at a time so you dont get confused which plug they go back on.) Once the wire is off the coil use an allen wrench, again dont know the size so just keep trying allen wrenchs until one fits snug, to loosen the coil clamps. Just dont drop the screws into the engine compartment. They are hard to find. Lift the coil out along with the coil springy silver thingy. Dont lose that either. (It pushes the coil down for a nice fit.) OK, now the sparkplug is down at the bottom of the hole. Use a spark plug socket, small one I think, and remove the spark plug. You'll need an extension about 8 inches long. Remove the spark plug then replace it with a new one, careful not to cross thread the new one. Tighten it by hand first using the socket and extension. Now using the wrench tighten it until its fairly snug, DO NOT OVER TIGHTEN IT!!!! Replace the coil with that silver springy thingy, plug the wire bundle back on your coil and your done with that one. Do this until all 8 are done and your ready for the road. :thumbsup:

They are really easy to get to. I replaced all mine in about an hour the first time. The hardest part was finding the right tools that fit the metric nuts and bolts. Good luck.

PS: If you ever need to replace your coils they are easy to change. Just do the above items all the way to the spark plug removal. Coils are easy!

Jeff
 

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1994 E320 Wagon,1999 E320 Wagon,2000 E 320 Wagon, MGB Track/Rally, ,1988 300E ,more....
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'01-E320 & 02-ST2
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to replace the connectors at the time you do the plugs.Big cause of misfires.
Your Parts Search Returned 1 Part(s)
ohlord:bowdown:
Just because it's Auto HAUS doesn't mean it will do him any good in Germany... :D:D

I'm sure you have sources over there, KC, and I'd agree with ohlord on this. The 420 V8 is known to be a bit of an odd duck.

Take care and enjoy the ride,
Greg
 

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2003 Mercedes Benz E500
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668 Posts
An "odd duck"...

with a following... They are great cars, with an engine that his quite a bit of racing history behind it, as opposed to the politically correct "ULEV" that followed.

And, actually, the "official," ohlord coined moniker on this forum is an "Orphan":D

JR


Just because it's Auto HAUS doesn't mean it will do him any good in Germany... :D:D

I'm sure you have sources over there, KC, and I'd agree with ohlord on this. The 420 V8 is known to be a bit of an odd duck.

Take care and enjoy the ride,
Greg
 

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MB E420T
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53 Posts
Discussion Starter · #6 ·
thanks for those answers...
indeed, saw a mechanic replacing plugs on a C-class yesterday that had the misfiring happen outside the connectors. so far, i only ordered new plugs.
from the (tv) show i could clearly see how to recognize a failing connector, so if i see one in my engine i will get to that also. Given the mileage i do (about 30000 a year) i look at multiple plug changes anyhow. This is also driven by the fact that i have a bi-fuel system, meaning: i have an LPG (liquid gas) installation. (V8 consumption at top speeds, with european gasoline prices.... u need to be a millionaire these days!) Anyhow, it all works brilliantly, just that the system is sensitive to the spark plugs, or vice versa.
btw citruspilot: aren't there 16 plugs on a V8? the 320 V6 has 12....
Tomorrow morning i will try to have a Mercedes mechanic show me where they are and how to best approach the job.... if i get that done without anyone wanting any money for that, i will be extremely surprised (yet happy)!
Stealership is a great word... to give you an idea: at the current dollar rate, i am looking at 6-700$ otherwise -parts and labor!
i will keep you posted...yet i am a visual guy... if i see somebody do it (pics) it will be muuuch easier ;)
greetz
 

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1994 E320 Wagon,1999 E320 Wagon,2000 E 320 Wagon, MGB Track/Rally, ,1988 300E ,more....
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Your

engine is the old v8 M119 engine and it has 8 plugs.The new engine is the m112 in v6 and it has twelve and the v8 m113 has 16 plugs.Your engine is a completely different engine.Layout,materials,cams,about 50 kg. heavier and nothing between them is interchangeable between your m119 and the two later engines.Spark plug process is totally different,except for the screwing out and screwing in.:D
:bowdown:
 

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2001 E320 - Brilliant Silver/Ash: 107,000+
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Stealership is a great word... to give you an idea: at the current dollar rate, I am looking at 6-700$ otherwise -parts and labor!...greetz
Hallo KC420,

Are you serious? $600-700 for changing 8 spark plugs? Or are you including a few connections and coils in that price? Jeff said it only took him 1 hour, and MB dealers here don't charge more than $150/hour. Luckily, my dealer is $92/hour the last time I checked. Anyway...

Good Luck mein Freund, und willkommen innen Benzworld!

Musikmann
 

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1997 E420 Sport AMG
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Running rough after plug change.

to replace the connectors at the time you do the plugs.Big cause of misfires.
Your Parts Search Returned 1 Part(s)
ohlord:bowdown:
Hello: I changed my plugs with no problem and the car is no running worse than before I changed the plugs. It seems to be misfiring, maybe on one cylinder. Is there a way to troubleshoot this problem? Please elaborate on replacing the connectors. In other words,why do you need to replace them? My connector boots seem to be supple and not hard. Is there something else here that you could tell me which might help? I would really appreciate hearing from you!

Thanks!

e-mail: [email protected]:surrender:
 

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'01-E320 & 02-ST2
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Hello: I changed my plugs with no problem and the car is no running worse than before I changed the plugs. It seems to be misfiring, maybe on one cylinder. Is there a way to troubleshoot this problem? Please elaborate on replacing the connectors. In other words,why do you need to replace them? My connector boots seem to be supple and not hard. Is there something else here that you could tell me which might help? I would really appreciate hearing from you!

Thanks!

e-mail: [email protected]:surrender:
Hey, bb. I realize you're frustrated but please don't bang out multiple posts for the same issue. It's not going to get you any quicker or better answers. You've started your own thread, so it's best to just stick with that one.
 
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