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Discussion Starter · #1 ·
Was just changing out the spark plugs on my 02 M5 with approx 165k miles, and noticed a good amount of rough looking carbon/oil/gunk buildup on the piston head.

Is this a normal looking amount for these cars? Has anyone else noticed similar while replacing their plugs?

Sorry for the poor picture, it was the best my phone could manage.

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Probably doesn't work:
"It depends, if the engine is able to get components hot enough then perhaps so." Get your oil temps past 200 and your in the proper range to burn off carbon.
So dont drive like a Karen and you will reduce carbon buildup.
Also, check oil separators or install a catch can. Most of that black **** is probably oil residue oppose to fuel residue.
 

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Most of that black **** is probably oil residue oppose to fuel residue.
That is the point, most of that black might be carbon, but there are tons of other things in that crud. Anything that could not burn.
The one important thing said in the vid is that guy is not a chemist. According to things that he said we should not get buildup of carbon on tail pipes, but we do. There is also another very significant thing the S62 does. It compresses exhaust gas in the EGR or Vanos working range and that is the main reason for the buildup on the pistons, SAS ports and exhaust valves. This process has nothing to do with range of temp. Most of that crud can be removed at idle spritzing water in the intakes. The carbon has not got a molecular bond to the metal, something else is going on. Something that has not been considered in the video as a cause.
 

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It's normal for any engine with 165k miles on it to show carbon on the piston, including a Honda! (gasp). Now factor in that it's an S62? Absolutely normal.

If you're worried there is too much build up, do as mentioned above and give it the old "Italian tune up". Besides higher temps helping to loosen and burn off deposits, so too will the higher air velocity moving through the engine. Personally, I'd replace the spark plugs before the "tune up" so you have optimal spark for combustion.
 

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Discussion Starter · #9 ·
Thanks for all the responses guys.

I do think the car was having an issue with oil leaking/burning, and I've replaced the oil separators/hoses that looked to be in bad shape. I'm hoping that might help a bit.

I've been doing a bunch of other work on the car the past few days so it hasn't been up and running.

Once I get it all put back together, it sounds like I have a good excuse to give it the beans more often.

I may look into some intake/combustion cleaners just to feel a bit better about it, even though I think that it might require more rigorous means of de-carboning.

Use GM top end cleaner.
Was this the one you were talking about, Steve?

Also does anyone have any other recommendations on cleaners to try?

Sailor, I've been reading a few threads and I've seen you have been pretty outspoken about seafoam not working particularly well. Are there any that you have tried that you've liked or is plain old water truly a good thing to use?
 

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You are close. Go to a Chevy dealer parts department. They will know and it comes in a liquid form. Use a small amount in the cylinder. 1oz or less and let it sit for hours or over night. Pull out what you can then burn the rest. Don’t breath in the fumes / exhaust the stuff is very strong and is the best you will find for this use.
 

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I run seafoam through the intake on my E61 and it keeps N54 valves somewhat clean eliminating need for intake removal and physical cleaning of carbon build up on valves due to direct injection.
Could help the S62 probably
 

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Sailor, I've been reading a few threads and I've seen you have been pretty outspoken about seafoam not working particularly well. Are there any that you have tried that you've liked or is plain old water truly a good thing to use?
Seafoam is just marketing. If you look up the new MSDS info you see that it is all hidden by trade secrets, just more games. There is nothing in it that will react with carbon other than Isopropyl Alcohol, which is carbon a fair bit of hydrogen and a tiny bit of oxygen. Not sure that reacts but I am told it does. .
All these videos I see on that crud like the one posted here. The dude poured some on top of the piston and the carbon vanished? Where did it go? It is an element it would have had to bond with something else to vanish. It would have been a little more convincing if we could see the carbon and was easily wiped off, but for it to vanish does not seem plausible. They used to claim the smoke show you got when you put it in the crank case was proof positive of it's effectiveness. Until some science guy did the same with just the alcohol and had the same results. The alcohol bonds with the moisture in the crankcase and that is what you get.
Here is the old MSDS, before they started trying to hide that there is nothing in the product.

GM stuff works and Dodge also has one. Both companies had engines that carboned up and created products to reduce the warranty claims. The fact that they did not have to replace too many engines is likely proof that their stuff works. Water works really well and has for many moons, just creates steam and that some how removes it over time. Junk yards have been doing that since they ripped out the first motor and put it up for sale.
The one that worked the best for me was Terra Clean, but that is a shop treatment and hard to find. I was chasing buildup on my exhaust valves and maybe in my cats.
There will always be some carbon on pistons, it is the nature of combustion. Be more concerned how much is sitting on the exhaust valves but they are near impossible to inspect. You can see how much you have, the picture did not really show things well.
 

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I should mention don’t use too much as you could hydrolock the cylinder
Good advice for any product he may consider using. IMO you need to know what you're doing to try water for that same reason. Too much water and you're going to have a bad day. lol.

Caution and restraint should be the words of the day.

OP - Finish up your maintenance and take it for 1-2 nice spirited drives (after warm up), holding shifts much higher into the rev range as you go, as possible anyway.
 

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Pouring anything in the intakes is not really a good idea. Even if you are planning to dribble it in you could slip and drop more of anything in that you intended. At minimum you should use a spritzing or squirter bottle to mist in the product even if it is just water. Both Chev and Dodge products come in spray cans.
The best thing to use is a vacuum bottle that you pour the product in and connect to the vacuum system, brake booster line is common. That meters out the product much slower and much more controlled, getting the most out of the product even if it is water.
 
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