How much carbon buildup is too much?

And how do I get rid of it?

Long twisty story - -  got up Friday morning, plugged in the coffee, made the dog's breakfast, then retired to check my three favorite websites.  Wifey gets up, gets ready to go to the gym, comes back upstairs "we have a problem".  Water is pouring out of the living room ceiling. 

I tore a 2 foot hole in the soggy ceiling and found a leaky drain ipe for the sink upstairs.  They needed an elbow so used a Tee and corked off one hole.  It rusted.  OK.  Two trips to the store and it's fixed.  I shoot a fan up there to dry things out.  That afternoon, Trish comes out to the garage, "We have a problem".  The commotion of Saw-Zalling a 2" metal pipe, rattled something else, I don't know where.  Ran to John's house to borrow his video camera with a 3 ft tube.  Lets look.  Found it 5 ft. away. 

 Well, I've got a camera, lets look inside the Goldwing jugs.  Huge carbon on top of the pistons.  I assume the 4 carbs were too rich, what else may cause carbon?  I'm rebuilding the carbs anyway but didn't want to pull the heads off.  With proper carb adjustment and maybe a hotter plug, will the carbon blow out?

Thank you for your patience.

In reply to 914Driver :

If it was mine, and if it wasn't a crazy amount of carbon the ol italian tune-up would be my go to. 

Steam cleaning the old-fashioned way. Get the engine hot, take maybe a quart of water (or Windex, or some combination of the two) and let the engine suck it in through a small-diameter tube into the intake. Restrict the flow - I use one of the small tips from a Mity-Vac kit, but really anything that will allow just a trickle of water in will do - and make sure the engine does not stall by manually operating the throttle throughout the procedure. You'll get big clouds of steam out the exhaust. Once the water's gone most if not all of your carbon should be gone too.

Both of the above suggestions should work, the first is a lot more fun though. 

I watched my uncle do that to a 425 Cadillac, that big four barrel sucked in some serious gulps of water.  Sure enough it cleaned out a bunch of carbon.

I one time took an 86ish Caprice, old lady to church and back car, with 80 thousand miles on it for on Italian tune up.  It left the biggest cloud of carbon and sparking chunks that I had ever seen come out of the tailpipe.  Previous to that I don't think the throttle had ever been past 1/4" travel and had trouble getting up to 55mph.

I've done the cold water bit, but what's an Italian Tuneup?

In reply to 914Driver :

A long hard run at high RPMs. 

High cylinder pressure and high temps burn the carbon out.

When your VW TSI engine has cold start misfires on a regular basis, you have too much carbon (on the backs of the intake valves), that much I can tell you for sure.  Beyond that, ????

Isnt the steam clean basically what seafoaming does?

Italian tune up: HOON IT.

Yeah, Seafoam has the same effect as the steam cleaning.

Does Seafoam do more, quicker, better?  I have no idea, but I suspect straight water is likely 90% as effective.

Running it hard will do nothing useful if it's pig rich at WOT too.  I like to spray NAPA carb cleaner down the engine's gullet with it running.

aircooled said:

Yeah, Seafoam has the same effect as the steam cleaning.

Does Seafoam do more, quicker, better?  I have no idea, but I suspect straight water is likely 90% as effective.

I'd bet that the water is better at it.  Non combustible, no chance of leaving additional carbon.  

Especially considering what seafoam actually is.  Not too much call for it with modern fuels.

Any of these operations carry the risk of knocking a big chunk of carbon off and sticking it in an exhaust valve, too.  A combination of softening agent with Italian tuneup will likely give you the best results, other than pulliong the heads and scraping.

Anyone have an E30M3 owners manual handy, they basically recommend an Italian tune up.  

After an amount of city driving immediately drive at a high engine speed for an amount of time.  Sure enough after a long road trip or track excursion it would idle smooth again.

You have too much carbon buildup when you have to start using race gas because it's so thick its raised the compression ratio.

In reply to akylekoz :

I wonder if BMW specified spark plugs a touch too cold for city driving.  That sure sounds more like fouled plugs than carbon deposits.

In reply to Pete. (l33t FS) :

Probably true, just funny that it’s spelled out in the owners manual.

In reply to akylekoz :

"YOU DRIVE LIKE A LITTLE GIRL"

You know how A2-chassis Golfs and Jettas had real bad problems with rear tires diagonal swiping because of all the static toe in and negative camber?  Apoparently in Germany that was called something that translates to "Old-Woman-Wear" because it happens if you drive like an old lady, if you cornered aggressively the tires would wear well.

If you place your pistons under the hand cleaner drip for about 6 months the carbon will while right off.

In reply to Pete. (l33t FS) :

It only happened once I swear.

I did let my girlfriend drive it to work once while I worked on her car, told her to keep it above 2 grand at least.  She came home and told me that it handles nice after she took a corner sideways in the wet.  We are going on twenty years of marriage.

You don't have to do anything crazy, just don't upshift.