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New DI Engines -- Excessive Carbon Buildup ??
#76
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2004 Mazda6, 1993 RX7
Intake Valve back side deposites are also a major DI problem ( as well as intake manifold ports) on many cars.
For each cylinder, could you put the intake wide open, the exhaust valve closed, and the piston at TDC, then using a fine grade of shells ( industrial products ), blast the intake valve and combustion chamber with a tube inserted in the intake port, with particles exiting the spark plug hole(s), and possibly the intake port too. ??
Clean out with vacuumed air, and perhaps a solvent chaser?
.
#78
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Nissan GT-R BE / '12 Ducati-1199 Panigale S / '12 C300-4M Loaded/GLK350-4M Loaded
Have you any experience with DI engines?
Intake Valve back side deposites are also a major DI problem ( as well as intake manifold ports) on many cars.
For each cylinder, could you put the intake wide open, the exhaust valve closed, and the piston at TDC, then using a fine grade of shells ( industrial products ), blast the intake valve and combustion chamber with a tube inserted in the intake port, with particles exiting the spark plug hole(s), and possibly the intake port too. ??
Clean out with vacuumed air, and perhaps a solvent chaser?
.
Intake Valve back side deposites are also a major DI problem ( as well as intake manifold ports) on many cars.
For each cylinder, could you put the intake wide open, the exhaust valve closed, and the piston at TDC, then using a fine grade of shells ( industrial products ), blast the intake valve and combustion chamber with a tube inserted in the intake port, with particles exiting the spark plug hole(s), and possibly the intake port too. ??
Clean out with vacuumed air, and perhaps a solvent chaser?
.
To answer your other questions, yes that was the procedure about 25-40 years ago, but no longer today. Most high performance engines, including DI (which isn't really new) have quad valve heads, that is 2 intake and 2 exhaust. Removing the intake manifold exposes only the twin intake pair, not the exhaust. Most spark plugs are crown mounted these days so vertical exiting will not work. The blast tip can be curved to get the back side of both intake valves at the same time. As far as the manifold is concerned, if it needs cleaning, it can be done very easily since it now off the car.
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#79
A cleaning solution injection (not Seafoam), done as part of periodic maintenance, can work. Of course if the condition is allowed to persist for a long period of time, it won't help much. But in an EFI engine, that intake rail is cleaned by the fuel/fuel detergents mixture - so it can be cleaned.
These DI engines are here to stay given the new fuel economy regulations - there is no perfect oil separation unit, so this is life from now on.
These DI engines are here to stay given the new fuel economy regulations - there is no perfect oil separation unit, so this is life from now on.
#80
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Nissan GT-R BE / '12 Ducati-1199 Panigale S / '12 C300-4M Loaded/GLK350-4M Loaded
![thumbs](https://mbworld.org/forums/images/smilies/thumbsup.gif)
I was hoping the Mercedes would have incorporated something like this, but sadly it appears they didn't.... fools.
![](https://mbworld.org/forums/members/mbredux-albums-gtr-picture25042-dual-injection.jpg)
*We'll see it first in the next generation MkVII Golf/GTI
Last edited by MBRedux; 02-15-2012 at 10:15 PM.
#81
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So what's the best way to determine that the carbon buildup is happening? Is the problem that the intake valves won't seal well? If so I suppose doing a compression test on the engine when it's new and then near the end of warranty would be a good enough indicator to decide to pull the intake and look into the head for buildup. Would proof of dropped compression and pictures of the engine with major carbon build-up be enough to force MB to fix this as a warranty item?
And as a follow-up, anyone know enough about these cars/engines to know how difficult it would be to remove the heads with the engine still in the car for a DIY project?
And as a follow-up, anyone know enough about these cars/engines to know how difficult it would be to remove the heads with the engine still in the car for a DIY project?
#82
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The problem is that it is a thick deposit, that restricts flow into the cylinder.
.
#83
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#84
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So an air fuel ratio reading / rich condition could be an indicator? Or would the computer just adjust the fuel downward if the carbon buildup causes air restriction? I'm just trying to find out how I can be certain when the problem happens so that I can try to get the dealership to fix it.
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I didn't think that deposits on the back of the exh valve head were a problem with DI or any engine, due to the high temerature it maintains, vs the intake valve. Every old head I pulled (non-DI) had no deposit on the back of the exh valve (especially the ones I polished for my race engine
).
.
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#87
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So what's the best way to determine that the carbon buildup is happening? Is the problem that the intake valves won't seal well? (NO) If so I suppose doing a compression test on the engine when it's new and then near the end of warranty would be a good enough indicator to decide to pull the intake and look into the head for buildup. (NO a Comp Test will not show very little if you have carbon build-up. If anything, the compression will be higher, not lower in engines with severe carbon build-up on pistons crowns. If the valves are carbonized, they rarely stick open these days due to better designs... so there probably won't be much if any compression loss through the intake valves. ) Would proof of dropped compression and pictures of the engine with major carbon build-up be enough to force MB to fix this as a warranty item? (Pix YES... use a probe!)
And as a follow-up, anyone know enough about these cars/engines to know how difficult it would be to remove the heads with the engine still in the car for a DIY project? (HUGE EFFORT and will void engine warranty if any is left)
And as a follow-up, anyone know enough about these cars/engines to know how difficult it would be to remove the heads with the engine still in the car for a DIY project? (HUGE EFFORT and will void engine warranty if any is left)
![](http://www.harborfreight.com/media/catalog/product/cache/1/image/370x/9df78eab33525d08d6e5fb8d27136e95/i/m/image_11494.jpg)
Last edited by MBRedux; 02-16-2012 at 03:34 PM.
#88
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So an air fuel ratio reading / rich condition could be an indicator? Or would the computer just adjust the fuel downward if the carbon buildup causes air restriction? I'm just trying to find out how I can be certain when the problem happens so that I can try to get the dealership to fix it.
Yes, and now they're very inexpensive. COSTCO has a camera probe that's in color with a detachable bluetooth screen for $125 bucks!
#89
Senior Member
Thanks for the info. I'll buy a boroscope and will probably get the car dynoed after the engine is broken in so that I have a base. No car, in this day and age, let alone a MB should have this as a concern...
If I do end up with the purchase, and have this issue come to fruition, this will be my last MB purchase.
![nix](https://mbworld.org/forums/images/smilies/nixweiss.gif)
#90
Interesting thread on another forum about the Audi 3.2L FSI - shocking stuff, photos, owner experiences. If the MB DIs do this, forget it:
http://forums.audiworld.com/showthread.php?t=2817781
http://forums.audiworld.com/showthread.php?t=2817781
#91
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![](http://sys9five.com:8080/etc/pictures/valves2/cyl4-valve2.jpg)
I think this thread is interesting as well. The owner of a Direct Injected VW/Audi took pictures of the carbon all over his intake valves at 50,000 miles. He cleaned them and installed a Catch-Can. After 38,000 additional miles, he took some more pictures... NO DIFFERENCE! http://forums.fourtitude.com/showthr...res-Discussion
Bottom line--- Catch-Cans are for suckers and Direct Injected Engines are no sweet angels!
![smash](https://mbworld.org/forums/images/smilies/smashfreak.gif)
Last edited by MBRedux; 02-17-2012 at 09:45 PM.
#92
You read these threads - Audi is in for some serious problems as this problem catches up to more owners as their mileage increases. And what about their certified pre owned cars, coming back with 30K miles and then they turn around and sell them used right around the mileage when these carbon problems are first occurring. They are going to have big problems with that. Mercedes must know what is going on with these Audis.
#93
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You read these threads - Audi is in for some serious problems as this problem catches up to more owners as their mileage increases. And what about their certified pre owned cars, coming back with 30K miles and then they turn around and sell them used right around the mileage when these carbon problems are first occurring. They are going to have big problems with that. Mercedes must know what is going on with these Audis.
Look at my posts.... Sadly it appears Mercedes may be walking in VAG's (Audi/VW's) footsteps.... There is no technical information available from anywhere to say otherwise.
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Last edited by MBRedux; 02-18-2012 at 12:22 PM.
#94
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The fact that diesel engines from good designers like Benz do not do this tells me that if this does prove to be an issue it is going to be very fuel dependent. SA fuel will only be Euro 4 in a years time. I shall keep my trusty boroscope handy & watch a few cars.
SA & US fuel is similarly crap at the present time.
SA & US fuel is similarly crap at the present time.
#95
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...The owner of a Direct Injected VW/Audi took pictures of the carbon all over his intake valves at 50,000 miles. He cleaned them and installed a Catch-Can. After 38,000 additional miles, he took some more pictures... NO DIFFERENCE! http://forums.fourtitude.com/showthr...res-Discussion
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![](http://mistertool.smugmug.com/Stuff1/group1/i-rw2Xdt7/0/M/scan0000037A-M.jpg)
Recognise this guy with the skinny legs?
.
#96
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The fact that diesel engines from good designers like Benz do not do this tells me that if this does prove to be an issue it is going to be very fuel dependent. SA fuel will only be Euro 4 in a years time. I shall keep my trusty boroscope handy & watch a few cars.
SA & US fuel is similarly crap at the present time.
SA & US fuel is similarly crap at the present time.
That may be so but I fear the worst. Why? These new DI engines are in response to the new Cafe' Fuel Standards imposed by the US-DOT back in 2002-04, then again in 2006-08. Manufacturers had little time to really make this work, to make it fuel efficient to meet these new regulations and bring it in at the right price. GM and Ford had issues early on but claim to have solved them. Toyota developed an entirely new induction and CC venting system along with incorporating advanced new valves & guides to reduce heat & friction thus enabling a better sealing valve guide cap. Audi/VW were in denial for many years as owners kept complaining of reduced engine performance and fuel mileage after a year or two of ownership... well they finally learned their lesson and are promising a dual injected engine line-up starting with the 2013 MY. This is an admittance of guilt IMO and will surly ruin their chances of a win in the courtroom. In the mean time they are still selling these defective engines... so go figure!
![nix](https://mbworld.org/forums/images/smilies/nixweiss.gif)
![EEK!](https://mbworld.org/forums/images/smilies/eek.gif)
But Mercedes is keeping mum on the topic... taking a wait & see attitude with their fingers crossed behind their backs.... I fear the worst.
Nice pics. It looks like krap builds up on back of intake valve, then perhaps the rough valve stem reams the valve stem seal, especially with a turbo where the seal is pressed hard against the stem by boost pressure. I say this due to the smooth "lava flow" gunk at the stem to valve head joint area.
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![](http://mistertool.smugmug.com/Stuff1/group1/i-rw2Xdt7/0/M/scan0000037A-M.jpg)
Recognise this guy with the skinny legs?
.
-----------------
![](http://mistertool.smugmug.com/Stuff1/group1/i-rw2Xdt7/0/M/scan0000037A-M.jpg)
Recognise this guy with the skinny legs?
.
As a young photojournalist way back when, (and a complete auto racing enthusiast and amateur engine builder at the time) I ran into Mr. Newman many times at Watkins Glen and at Lime Rock once in awhile. (He and Bob Sharp are the ones who got me stuck on Nissan Racing/Nismo and I've never looked back)
Paul was a true gentleman and a regular guy who loved talking cars, racing, and the thrill of life....
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![](http://obit-mag.com/media/image/horizontal4.jpg)
Last edited by MBRedux; 02-18-2012 at 01:01 PM.
#98
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As a young photojournalist way back when, (and a complete auto racing enthusiast and amateur engine builder at the time) I ran into Mr. Newman many times at Watkins Glen and at Lime Rock once in awhile. (He and Bob Sharp are the ones who got me stuck on Nissan Racing/Nismo and I've never looked back)
Paul was a true gentleman and a regular guy who loved talking cars, racing, and the thrill of life....![thumbs](https://mbworld.org/forums/images/smilies/thumbsup.gif)
Paul was a true gentleman and a regular guy who loved talking cars, racing, and the thrill of life....
![thumbs](https://mbworld.org/forums/images/smilies/thumbsup.gif)
I built a "Modified" SCCA D-Production engine for my street Triumph GT-6. Illegal mods included triple 40DCOE webers, custom tuned by me. The compitition manual was written by Eng'g chief Mike Barrett, who later led the Monster Nissans in that wild and open Prototype class that included the unbeatable 2.2L Toyota turbo's managed by Dan Gurney, another great guy to talk with.
![](http://mistertool.smugmug.com/Stuff1/group1/i-B5DZJfn/0/M/scan0000040A-M.jpg)
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#99
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I was recently at the philly auto show (a shadow of it's former self) and gauking at a ford 4 banger cutaway, when I noticed a slight Asian gentleman in a suit, gauking at the same engine, but taking copious notes. He had missed the cutaway combustion chamber in the hard to access rear of the display, and I showed him how to climb up to the spot. He was a DI consultant for Ford Engines, stated he knew nothing of carbon problems (doubt it), but I think he was talking about varying rail pressure as part of the injection control, and elimination valve overlap at low rpm to reduce build-up.
.
.
#100
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Agreed. I saw him a few times with Bob Sharp, at Summit Pount Raceway. 1st in a GT2? 280Z type machine, later in a 300Z (TT?) GT1 monster. He rarely made a mistake, but definitly had reliability issues.
I built a "Modified" SCCA D-Production engine for my street Triumph GT-6. Illegal mods included triple 40DCOE webers, custom tuned by me. The compitition manual was written by Eng'g chief Mike Barrett, who later led the Monster Nissans in that wild and open Prototype class that included the unbeatable 2.2L Toyota turbo's managed by Dan Gurney, another great guy to talk with.
.
I built a "Modified" SCCA D-Production engine for my street Triumph GT-6. Illegal mods included triple 40DCOE webers, custom tuned by me. The compitition manual was written by Eng'g chief Mike Barrett, who later led the Monster Nissans in that wild and open Prototype class that included the unbeatable 2.2L Toyota turbo's managed by Dan Gurney, another great guy to talk with.
.
![Smilie](https://mbworld.org/forums/images/smilies/smile.gif)
I was recently at the philly auto show (a shadow of it's former self) and gauking at a ford 4 banger cutaway, when I noticed a slight Asian gentleman in a suit, gauking at the same engine, but taking copious notes. He had missed the cutaway combustion chamber in the hard to access rear of the display, and I showed him how to climb up to the spot. He was a DI consultant for Ford Engines, stated he knew nothing of carbon problems (doubt it), but I think he was talking about varying rail pressure as part of the injection control, and elimination valve overlap at low rpm to reduce build-up.
.
.
![thumbs](https://mbworld.org/forums/images/smilies/thumbsup.gif)
Last edited by MBRedux; 02-18-2012 at 04:55 PM.