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2001 SL600 AMG
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119 Posts
Discussion Starter #1
Could someone share with me what is proper procedure for changing out all 12 plugs on a R129 V12. I mean, is it just like any other car? Any special dealer tools? What should the plugs be gaped too and torqued at?
I have a 2001 sl600 with original plugs and 100k on the odometer. Car has always run beautiful. I assume I should do a plug change while the weather is still nice? Plug wires look in nice shape!!
Thanks for any input!
 

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2007 911 GT3 RS, 1990 420SEL, 2007 S550, 1994 SL500 6.0, 2011 Aston Martin DBS
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522 Posts
If the car calls for F-8 DCO plugs, get your hands on the Bosch FR8DC+ plugs. Dont go for Platinum's or anything else, you need a spark plug with no resistance really because your sparkplug wires have 2 K resistance in them.

I just did this today and I forgot the gap, but it should be on the box for the Bosch Super Plus, 0.03mm?, and torque it to 21 foot pounds.

No special tools just be patient with the 12 plugs. I think the M113 V8's have 16 plugs lolol.
 

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Premium Member
95 SL500, K&N, NEOKEN Ported TB, Custom Intake, RENNtech Sport Exhaust, AMG I Monoblocks
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10,980 Posts
Information in regards to BOSCH spark plug gapping can be found at BOSCH SPARK PLUG FAQs .

Bosch spark plugs are pre-gapped for their most popular applications, however, the gap can be altered if the plug is dropped or mishandled in packing/shipping. Therefore even if the plugs are supposedly preset for your motor, it is always wise to check the gap on each plug prior to installing. For information on how to adjust the gap see Proper Gapping.

Bosch spark plugs are pre-gapped at the factory, in most cases the factory set gap should conform to your vehicle specifications. However if it is necessary to widen the gap, do so with a tool that only pulls back on the ground electrode without touching the center electrode or the porcelain. To close the gap on a plug, gently tap the plug, electrode first on a hard surface. (see adjacent illustration)


 

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Registered
2001 SL600 AMG
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119 Posts
Discussion Starter #5
Plug change

Got the newest updated 7422 Bosch plugs and doing a spark plug change on my 2001 SL600 this weekend.
FR8DPP33+ These are new design stock and not that easy to find.
I ordered the plugs from AutoHausAZ. Got a great price on them too @ $4.47 ea. $17.95 list plus free shipping.
 

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Outstanding Contributor
1997 SL600 Brilliant Silver Sport with grey/dark metal interior, 234K miles
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1,977 Posts
The Bosch plugs that begin with FR are resistor plugs. I use non-resistor NGK. The stock short plug wires (SL600) have a 2K ohm resistor built-in. Resistor plugs typically have a 5K ohm resistor built-in. 7K ohms where only 2K should be might cause something to heat up or expose a weak electrical part (coil).

As to your question of how hard it is to R/R the plugs, not hard at all if you are mechanically inclined.

Just open the coil cage, disconnect the coil wiring and pull out the coil/plug wire unit. The plugs come out easily enough and the stubborn ones come out easier with a small breaker bar.

I think I used .032 of an inch for gap, but check your owners manual (it's in there).

The hardest plugs/coils to get to are the one's at the rear of the American driver's side of the SL600 that are partially obscured by the FI and vacuum brake lines. Takes 2 hours at best or you are doing something wrong.

If you don't have a good plug socket to fish out the plugs, use a short lenght of 10mm ID hose to grab the plugs.
 

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1993 300SL,
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23 Posts
Correct sparkplug gap ?

After 17 years and 60,000 miles it seemed like time to change my plugs, wires, rotor and cap. I have a question I have not been able to find an answer to in searching this forum or on any other forum.

Whats the correct plug gap?

I replaced the original plugs with the exact same Bosch F8DC4 plugs. The original plugs I removed are all gapped at about 1.0mm, but the new plugs are gapped much tighter at .80mm out of the box. So the question is, have the originals opened up in gap over the years or are my new ones gapped too tight?

I went to the Bosch web site and found no help there, I checked my Star Service CD and it makes no mention of the correct gap.

The car seems to run fine with the new plugs gapped at .80mm, but....I'd like to know its right.

Anyone know the answer?:confused:

Kevin
 

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Outstanding Contributor - Always Remembered, RIP
Zotye Auto 1.5T T600 2016
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52,804 Posts
We do not gap plugs anymore, provided you buy the correct plug for the engine then it comes with the correct gap.
 

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Premium Member
95 SL500, K&N, NEOKEN Ported TB, Custom Intake, RENNtech Sport Exhaust, AMG I Monoblocks
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10,980 Posts
You buy the correct plug for the engine then it comes with the correct gap.
Eric is correct as these plugs are indeed pre-gapped from the factory.

However, as mentioned above BOSCH suggests that you double check and adjust if necessary.
 

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Premium Member
95 SL500, K&N, NEOKEN Ported TB, Custom Intake, RENNtech Sport Exhaust, AMG I Monoblocks
Joined
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10,980 Posts
Get your hands on the Bosch FR8DC+ plugs. Dont go for Platinum's or anything else.

I just did this today and I forgot the gap, but it should be on the box for the Bosch Super Plus, 0.03mm?, and torque it to 21 foot pounds.
Stamped on the original F8DC4 BOSCH packaging specifies...

(0.8mm) spark plug gap, and (28Nm) which is equivalent to (20.6ft-lbs) tourque to be exact.

Apologies for not being able to provide a clearer photo, it is difficult to focus my lens on such small print.

Newton Meters to Foot-Pounds Conversion Calculator
 

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Greek God of the R129
SL500-500SEL-190E
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8,391 Posts
Trust no one always check the gap.
I always find a few out of range.
Or is it just me? Haha.
Neglect and coils will go bad.

Regards,
aam.
 

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Registered
'96 SL500, Triple Black
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1,650 Posts
It's just you aam, every single one of mine have been to specs. ;)

Ken, Find a macro focus, yeesh., my eyes are crossing. :)
 
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