I just picked up 8 spark plugs from the dealership... do I need to have these plugs gapped or are they ready to fit in? Also, do I need to put some sort of anti-seaze on the threads or do all these new bosch spark plugs come with a coating already on? I appreciate the input.

Yes, gap them and yes, but anti seize.

Bosch plugs come factory pre-gapped. The value is printed on the box.

Check them at least, but chances are abour 99% they're just what you require.

This is always amazing news to so many.

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Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles

Always check the gap. If someone at the dealer dropped a plug that could knock the gap out.

I always put anti-seaze on the threads when I change plugs. Aluminum heads are not forgiving!

Also don't crank the plugs down real hard, just tighten then enough to crush the seals. They are not lug bolts lots of torque can strip the head.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

The correct way to tighten new plugs with the crush ring is to tighten by hand and then go 3/4 of a turn with the plug wrench. If you are retightening a crush ring plug, only tighten 1/4 of a turn. Tightening a taper seat plug calls for tightening 1/4 of a turn only. Anti-seize is needed to prevent problems later on. When removing old plugs, break them loose a 1/2 turn and then blow out the plug well with compressed air to get rid of debris.
Tim

Those H9DCO from the dealer does not have seals on them, so guys ....give him another procedure in order to thight them right.

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Radu Negru

Thanks guys!

Absolutely use anti-sieze. I had a tune-up shop do the first tuneup on an old Pontiac 1.8 (aluminum head) that I had. They didn't use anti-sieze, I did the next tune-up, one plug got stuck, the plug broke, and only a miracle and an EZ-OUT kept me from an expensive, head-off replacement. But that was a cheap engine!

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http://juliepalooza.8m.com/sl/mercedes.htm

Lyonstex gave him the procedure for tapered plugs.. go re-read his post..
90 degree turn after seat , which equates to 10/20 Nm ..
As a matter of fact, he gave all the procedures , both new, used , ring washer, and tapered seat, plus a couple of other tech tips to boot ...
Do you have some Tech info he forgot to mention?????

I bet MB has a torque spec for them. If you have access to a torque wrench I would use it. But I have never felt the need to use one with plugs, I always have done them by feel and have never had a plug get stuck on me.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

<>
As posted .. 10/20 Nm
. and a 90 degree turn from seat position is 10/20 Nm..