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Duramax 6600 Discussion Forum for the Duramax 6600 Diesel Engine, including the LB7, LLY, LBZ & LMM engine specific topics.

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  #1  
Old 08-19-2009, 12:48 PM
tkgmfan tkgmfan is offline
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Default Excessive black smoke

I have a 2001 with 155.000 miles. It is blowing excessive black smoke and has had a PO234 code for overboost. Running down the highway at 70-72 with the cruise set it will blow smoke every time the boost goes above 10 psi. I had a couple of holes in the drivers side intercooler tube welded up just before the code started. I am trying to check my waste gate actuator. When I applied about 30 psi shop air I couldn't hear any air leaks but it took about 40 psi to move the rod. The waste gate arm only moved about 3/8". Is this all that it should move? I suspct that I might have multiple issues, possible some bad injectors also. Any help would be greatly apprciated
Tom
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Old 08-19-2009, 08:08 PM
DmaxMaverick DmaxMaverick is offline
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It takes very little WG movement to dump a lot of boost. The reason for the high PSI shop air test is there's 1/2 of the force missing. Exhaust back pressure, which is nearly 1/2 of what is necessary to overcome the WG actuator spring tension. Once exhaust back pressure is bypassed (via the WG), boost can be dumped, or regulated, depending on how much the WG is allowed to open. Technically, with this system, we are regulating the exhaust pressure, which in turn regulates the boost pressure.

Black smoke could indicate an air filter due for a change. The overboost code at the same time is curious, though. I'd start by inspecting/replacing the WG actuator air line. Could be blocked internally, which could delay WG actuation.
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  #3  
Old 08-20-2009, 07:56 PM
tkgmfan tkgmfan is offline
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Quote:
Originally Posted by DmaxMaverick View Post
It takes very little WG movement to dump a lot of boost. The reason for the high PSI shop air test is there's 1/2 of the force missing. Exhaust back pressure, which is nearly 1/2 of what is necessary to overcome the WG actuator spring tension. Once exhaust back pressure is bypassed (via the WG), boost can be dumped, or regulated, depending on how much the WG is allowed to open. Technically, with this system, we are regulating the exhaust pressure, which in turn regulates the boost pressure.

Black smoke could indicate an air filter due for a change. The overboost code at the same time is curious, though. I'd start by inspecting/replacing the WG actuator air line. Could be blocked internally, which could delay WG actuation.
Thanks for taking the time to reply, it is greatly appreciated. I will try replacing the actuator air line. The K&N filter was just recleaned and lightly reoiled. We did a scan tool balance test last night and injectors 4 & 6 look be be having issues. Looks like I will be replacing some injectors. I made the mistake of replacing just 1 injector (#2) a few months back. I won't do that again. Tomorrow I hope to pull the glow plugs and see what they look like on both sides of the engine. I will try to update as I make any progress.
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Old 08-21-2009, 05:10 AM
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Mark Rinker Mark Rinker is offline
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Lose the K&N, they pass too much fine particulate. No place for 'em on diesels.

Was recently up in AK, talked to a Ford diesel tech who said the grit from glaciation passed right through these filters and would take out engines in short order.
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Old 08-22-2009, 01:05 PM
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Shed Shed is offline
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Mark, does that go for all the aftermarket air filters? Or was he just referring to the K&N? I'm running an airaid, just curious.... Shed
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  #6  
Old 08-22-2009, 06:02 PM
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Mark Rinker Mark Rinker is offline
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I believe that concensus is all oiled-gauze style filters will pass more fine particles than their OEM paper counterparts. Turbocharged diesels consume vastly greater volumes of air than a naturally aspirated gasser. The factory engineers have it right on this one.

Do the 'white towel test'. Using a perfectly clean white cloth, remove your aftermarket filter and run it thoroughly over the entire inside of the inlet tube between filter and MAF. On a correctly maintained OEM setup, the towel will come back perfectly clean.

If yours does, too - then I am wrong. However, I am betting if you are running oiled gauze, and live on a gravel road (Iowa) it will come back dusty.
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  #7  
Old 08-25-2009, 07:57 PM
tkgmfan tkgmfan is offline
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Now for an update. I replaced injectors 4,6,&8 and the hose to my boost actuator over last couple of days. Took it out today and after a few hard pulls the smoking went away and my boost gauge never went over 23 lbs. My son-in-law put #2 in a few months ago(trying to save some $ by only doing one) for me, but this time he was busy so I did it myself. Not really a hard job, just a lot of things to remove before you got to the valve covers. I followed the steps from the injector replacement on this site. It provided a lot of great info was very helpful. My thanks to the author. My only comment/ warning to others is that the valve covers on the left side of the truck are a lot closer than on the right side making it really hard to get the back bolts in and out of the upper and lower valve covers. This was my first experience working on a diesel other than routine maintennace items, although I have worked on gas engines for a long time. I'm sure that I will probably have to replace the other 4 injectors in the future, but this will give me a chance to save smoe money first. My naxt project is to replace the rear half of the transfer case and put in the Kennedy plate so I don't get another hole. Does anyone know of a paper filter that will fit on a K&N cold air kit? Otherwise Iguess Iwill have to see if I can put the factory stuff back in.
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