Spark Plug Oily Threads?
#1
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Spark Plug Oily Threads?
Looking for some feedback - I changed plugs today, installed NGKs to replace Bosch. Both are the oem replacement number plugs. The Bosch only had 1000 miles on them but I've been really curious about mileage differences between them and the NGKs so I decided to splurge a bit and try the NGKs.
Car runs fine on both sets but here's what got my attention. For just 1k miles the threads seem to be dirtier than I would expect and #6 on the right has oily threads. Not dripping just kind of gunked. The ceramic part on all plugs is very clean.
All plugs torqued to 17 ft lbs, no anti-seize used, installed on cold engine. Dielectric grease used inside boots. Car has about 54k miles.
I don't recall the original Bosch set being dirty enough to catch my attention.
Anyway maybe this is not a big deal but I'd be curious to know what you think.
Car runs fine on both sets but here's what got my attention. For just 1k miles the threads seem to be dirtier than I would expect and #6 on the right has oily threads. Not dripping just kind of gunked. The ceramic part on all plugs is very clean.
All plugs torqued to 17 ft lbs, no anti-seize used, installed on cold engine. Dielectric grease used inside boots. Car has about 54k miles.
I don't recall the original Bosch set being dirty enough to catch my attention.
Anyway maybe this is not a big deal but I'd be curious to know what you think.
#2
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They look normal to me. Was there oil in the plug well when you swapped them? I wouldn’t worry about it.
#3
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No oil in the wells at all, just that bit on the threads.
I appreciate your feedback - sometimes another set of eyes adds better sense. I'm also inclined to think it's ok after mulling it over and thinking about the plugs I've changed over the years.
I appreciate your feedback - sometimes another set of eyes adds better sense. I'm also inclined to think it's ok after mulling it over and thinking about the plugs I've changed over the years.
#4
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There is no sign of oil burning on the tip of #6 (or any of them). The tips look all the same which is good, but again it was only 1k. I wouldn't worry about it if you not seeing oil in the tube getting past the seal.
#5
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2010 W212 E550 4matic
Check your oil drip pan breather hose, the one entering the intake below the MAF. If there's excessive oil there you'll have your explanation for the burnt oil residue on the threads.
A thin coat of oil around the inner lining of that hose shouldn't be a reason for concern, oil dripping out of the hose when you pull it out should.
A thin coat of oil around the inner lining of that hose shouldn't be a reason for concern, oil dripping out of the hose when you pull it out should.
#6
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Good idea, thank you. I checked and that hose is quite dry. There's a very slight film at the catchcan end but the rest of it looks good. Def no oil accumulated inside. I know that pcv assembly is suggested to be inspected regularly.
My service rep at MB dealer has been exceptional and very helpful. I'm going to stop by for a wash and ask his and/or tech opinion. Yes I know they can put you off on repairs but this dealer has been the opposite, gone above and beyond for me.
When checking that pcv, I noticed a small amount if what looks like accumulated oily seepage on the block between catchcan and MAF. Going to ask them to check, car goes off ELW mid November , better ask now lol.
My service rep at MB dealer has been exceptional and very helpful. I'm going to stop by for a wash and ask his and/or tech opinion. Yes I know they can put you off on repairs but this dealer has been the opposite, gone above and beyond for me.
When checking that pcv, I noticed a small amount if what looks like accumulated oily seepage on the block between catchcan and MAF. Going to ask them to check, car goes off ELW mid November , better ask now lol.
#7
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I had a small leak in that area as well. If it's on the back of the cylinder head/passenger side it's caused by the oil separator's cap seal, that's a very easy and cheap fix. https://www.ecstuning.com/b-hamburg-...720100631~ham/ . There's a whole kit you can buy on this site, that's what I got for refreshing the PCV system ( https://www.ecstuning.com/b-assemble...2730180582kt1/ ).
You might only need that cap though, if there's no seepage into the intake manifold. This cap has a rubber gasket to the block, that can leak oil and makes a visible mess.
On mine, the intake manifold was full of oil, to the point where it was coming out through the front part where the vaacumatic intake runner actuators connect to the intake housing. Even the electrical connectors had oil coming out of them.
The main culprit for this was the vacuum actuated seal inside the oil separator cap, it was hardened and shrunken allowing oil to go past it into the intake area. The HT one is supposedly an upgraded part so this issue shouldn't appear in the future. It's a good idea to have them replace it if it's leaking, I chose not to do it when they quoted 450$ for replacing the oil separator cap.
For your engine :
https://www.ecstuning.com/b-assemble...2720181382kt1/ - mixed brands parts
https://www.ecstuning.com/b-genuine-.../2720181382kt/ - MB parts
You might only need that cap though, if there's no seepage into the intake manifold. This cap has a rubber gasket to the block, that can leak oil and makes a visible mess.
On mine, the intake manifold was full of oil, to the point where it was coming out through the front part where the vaacumatic intake runner actuators connect to the intake housing. Even the electrical connectors had oil coming out of them.
The main culprit for this was the vacuum actuated seal inside the oil separator cap, it was hardened and shrunken allowing oil to go past it into the intake area. The HT one is supposedly an upgraded part so this issue shouldn't appear in the future. It's a good idea to have them replace it if it's leaking, I chose not to do it when they quoted 450$ for replacing the oil separator cap.
For your engine :
https://www.ecstuning.com/b-assemble...2720181382kt1/ - mixed brands parts
https://www.ecstuning.com/b-genuine-.../2720181382kt/ - MB parts
Last edited by Oda112; 10-19-2018 at 01:11 PM.
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#8
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Great info, thanks. I asked to bring the car in next week for a look. Knowing how I am I may swap out that catchcan in the near future . Appreciate the links (saved).
#9
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Pcv centrifuge/cap was replaced under warranty - Oda you were spot on. Leakdown etc was checked as well as valve cover seals and nothing was found to be out of order related to the spark plug threads.
I did want to mention that for virtually same drives at same conditions and speed mileage has increased with the NGK plugs. This sounds nuts I know but for the first time I've seen a hair over 30 mpg at times on the readout. Readily admit a non-scientific analysis but I'm amazed there is a difference almost at all times.
I did want to mention that for virtually same drives at same conditions and speed mileage has increased with the NGK plugs. This sounds nuts I know but for the first time I've seen a hair over 30 mpg at times on the readout. Readily admit a non-scientific analysis but I'm amazed there is a difference almost at all times.
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#10
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Pcv centrifuge/cap was replaced under warranty - Oda you were spot on. Leakdown etc was checked as well as valve cover seals and nothing was found to be out of order related to the spark plug threads.
I did want to mention that for virtually same drives at same conditions and speed mileage has increased with the NGK plugs. This sounds nuts I know but for the first time I've seen a hair over 30 mpg at times on the readout. Readily admit a non-scientific analysis but I'm amazed there is a difference almost at all times.
I did want to mention that for virtually same drives at same conditions and speed mileage has increased with the NGK plugs. This sounds nuts I know but for the first time I've seen a hair over 30 mpg at times on the readout. Readily admit a non-scientific analysis but I'm amazed there is a difference almost at all times.
#11
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I'd seen other posts about the NGK and mileage, I'm a believer now lol. Dealer was good , they "found" and fixed a couple of other things under ELW warranty.
Car is now officially out of warranty today 😳 so like Tavarish on YouTube says I am the warranty!
Car is now officially out of warranty today 😳 so like Tavarish on YouTube says I am the warranty!
#12
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You better get acquainted with Harbor Freight then (if you haven't already), that's where he gets most of his tools. I haven't been watching most of his recent uploads, I'm not very interested in his Lambo or any of his cars, except the W221 and W220.