# engine knock on a 07 6.6 duramax



## Chevy 2500 hd (Jan 30, 2008)

I just got my first diesel in june its the 07 classic 2500hd with the 6.6 duramax has 10,200miles on it and 600hr on the engine I guess the best way to discribe the sound is a knock from about 700 rpm(idle) to 1200rpm the oil pressure is at 40 coolant temp is just below 210, once it goes above 1200rpm and oil pressure goes to 60 it sounds fine and it just started to do it today when I went to plow I guess to me the sound wasn't normal. Didn't know if I should be getting it looked at by the dealership or not?


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## exmark1 (Nov 30, 2005)

Chevy 2500 hd;532625 said:


> I just got my first diesel in june its the 07 classic 2500hd with the 6.6 duramax has 10,200miles on it and 600hr on the engine I guess the best way to discribe the sound is a knock from about 700 rpm(idle) to 1200rpm the oil pressure is at 40 coolant temp is just below 210, once it goes above 1200rpm and oil pressure goes to 60 it sounds fine and it just started to do it today when I went to plow I guess to me the sound wasn't normal. Didn't know if I should be getting it looked at by the dealership or not?


Well you have a warranty, I would get it looked over before something completely fails!


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## ABES (Jun 10, 2007)

Keep bringing it to the dealer until its fixed right eventually they will get sick of seeing it in the shop and they will fix it right. I would be pissed if i gave up 40k for a new truck and the motor started making noise.


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## tuney443 (Jun 25, 2006)

Why wouldn't you get it looked at---you have a great 5 yr./100K mile warranty? I've had 3 Dmax's----all great trucks-very rare that one gets an engine knock but hey,it's man made--nothing's perfect.Let us know how it goes.


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## lilweeds (Aug 3, 2007)

Are you sure it's a knock, diesels do make more know, and a low RPM noise is fairly normal!


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## Chevy 2500 hd (Jan 30, 2008)

Ok I was going to have it looked at no matter what I stated my question the wrong way I want to know if anyone else had this. rsvees I know its norm for them to be loud at low rpm but this noise just started all winter long the truck has perd like a kitten at low rpm but now it makes a loud knock til it hits 1200 and then goes back to a nice smooth sound. I love this truck all the power I could ask for a better truck


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## farmboy52787 (Mar 22, 2007)

junk it! go back to a gas job lol, then you dont have to worry about water in the fuel and getting stranded!


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## Spitz (Feb 28, 2008)

I was going to tell you the pilot injection is turning off but that only happens at around 2300rpm+, not at idle through 1700. Definatly would take it in and have it looked over if its happening when its fully warmed up like you stated.. At least if you take it in and have it documented and it blows up later on down the road they have that record of you showing concern..


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## tuney443 (Jun 25, 2006)

Chevy 2500 hd;533053 said:


> Ok I was going to have it looked at no matter what I stated my question the wrong way I want to know if anyone else had this. rsvees I know its norm for them to be loud at low rpm but this noise just started all winter long the truck has perd like a kitten at low rpm but now it makes a loud knock til it hits 1200 and then goes back to a nice smooth sound. I love this truck all the power I could ask for a better truck


Are you possibly talking about your elevated idle engaging?I mention this because 1150-1200RPM is exactly the point where that feature will take the Dmax.If your engine is real cold{1 of the parameters for engagement},you will get the ''concrete mixer or marbles growling'' type noise or in your mind a ''knocking''.This is completely normal and is a great tool for faster warmups.And just for the record,the Dmax is the quietest diesel at ANY RPM of the 3 diesels out there in any form,from the LB7 to the LMM version.


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## Chevy 2500 hd (Jan 30, 2008)

no I dont have the elevated idle option I only have the LT1 so there are no steering wheel controls and anyways its already up to temp and plus I keep it plugged in


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## OhioPlower (Jan 13, 2004)

Your truck has elevated Idle. My 07 dump has elevated idle and its the base trim level. I cant remember how to turn it on though, its in your manual


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## tuney443 (Jun 25, 2006)

Chevy 2500 hd;533364 said:


> no I dont have the elevated idle option I only have the LT1 so there are no steering wheel controls and anyways its already up to temp and plus I keep it plugged in


Yes,you do have the elevated idle.Take out your supplement and do a read.I don't have the programmable wheel either.And even with what you do,another parameter of the elevated idle to engage is the outside air temperature.If you have it engaged and it's colder than 32*,it will come on.


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## Chevy 2500 hd (Jan 30, 2008)

ok but why would it be on the trucks up to temp when it first started idk im still going to take it in rather then ignore it and have everything go to hell. Thanks for the info thow I'll have to go read and see how to turn it on


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## Chevy 2500 hd (Jan 30, 2008)

Ohio plower you turn the ign to run hold the throttle all the way down press the brake 3 times in 8 sec it will flash on the screen elevated idle on or off. Tuney443 it says it will turn off by its self which idk maybe theres a bad sensor but I could tell the dif with it on so I really don't think its that. this is what a gm tech said on another site thats all about the duramax *gmtech4* possible fuel knock,they should check your balance rates and find the injector that is the culprit,take it in


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## tuney443 (Jun 25, 2006)

Having trouble understanding you some. What does idk stand for? If you got your info from a GM tech at the DP,your in good hands. The elevated idle will turn off by itself,but only when certain parameters aren't met.Once you hit your brake or clutch,it would also disengage.Keep us posted.


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## OhioPlower (Jan 13, 2004)

idk= I dont know


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## Philbilly2 (Aug 25, 2007)

If you know someone who has a Preadator Box (programer) you can check your own balance rates.

The knock that you sound like you are having has nothing to do with the fact that your high idle is on or off. To me it sounds like the high idle will just cover up the problem. It will stil knock until the high idle engauges. 

Your oil pressure sounds right by the gauge.

I would get your balance rates checked. If one injector is not firing properly, that could cause a knock from lack of fuel at the correct time.


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## tuney443 (Jun 25, 2006)

Philbilly2;534083 said:


> If you know someone who has a Preadator Box (programer) you can check your own balance rates.
> 
> The knock that you sound like you are having has nothing to do with the fact that your high idle is on or off. To me it sounds like the high idle will just cover up the problem. It will stil knock until the high idle engauges.
> 
> ...


I thought this as a possibility Philbilly because I;ve seen some Dmax owners get spooked when they hear the engine spool up for the first time in elevated idle,especially if it's real cold.Now that we know more about what's going on,your hunch is probably right.He doesn't need a Predator or any other programmer right now though because he's still under warranty. If it is an injector problem,the dealer will fix it.


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## Philbilly2 (Aug 25, 2007)

tuney443;534939 said:


> I thought this as a possibility Philbilly because I;ve seen some Dmax owners get spooked when they hear the engine spool up for the first time in elevated idle,especially if it's real cold.Now that we know more about what's going on,your hunch is probably right.He doesn't need a Predator or any other programmer right now though because he's still under warranty. If it is an injector problem,the dealer will fix it.


No, I was just saying to use the Preadator box to check the balance rates. The Preadator box has a function on it where you can plug it into any truck even if the tune is installed in another truck. You start the truck and check the balance rates of all eight injectors. If all of the numbers are the same, your fine. If one number differs, then you know when you got into the dealer that you have an injector problem and they can't give you the normal run around.


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## Yaz (Apr 13, 2005)

Just take it to good dealer that services diesels, not just any one. Most dealers don't have a good Diesel mechanic so it's important to find one that does. Hopefully it's just a injector sticking. If it wasn't under warranty I would try this.. Guys that have had this problem say to run some diesel additive in large dose or 2cycle in fuel to clean the injector.


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## Chevy 2500 hd (Jan 30, 2008)

Ya the trucks at the dealership the truck started to have blue smoke, the knock got louder and shake so I took it to the dealership right away


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## Spitz (Feb 28, 2008)

Wow, definatly sounds like an injector issue if its running rough and smoking.. I know the 05s had issues with the harness rubbing through and causing issues but the 07 is a different engine.


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## Smokinlbz06 (Feb 14, 2007)

sounds like and injectors hung.................


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## Yaz (Apr 13, 2005)

Good reason to run a pre filter.. I run the the Nicktane... Works awesome and cheaper to service in the long run.


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## tuney443 (Jun 25, 2006)

You're right Yaz on the trying to get a good diesel tech but after extreme discussion on the soundness of using 2 cycle oil from factory oil experts,I wouldn't advise using it.I used to in addition to my favorite additive {Howes,for 34 years},and it actually made my already super quiet LBZ even quieter,but after hearing what these guys said about long term consequences, I stopped.To each their own.There are still plenty of old timers out there who will tell you to do an occasional clean-out with lacquer thinner or ATF


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## Chevy 2500 hd (Jan 30, 2008)

Turns out there was a few bad injectors all under warranty hopefully have the truck back tomarrow


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## farmboy52787 (Mar 22, 2007)

Question 

Can bad fuel cause injector problems?


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## Philbilly2 (Aug 25, 2007)

Yes if it lacks the right part of the diesel fuel, injector problems are just some of the problems that can arise.


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## tuney443 (Jun 25, 2006)

Chevy 2500---the dealer will probably do it for you but just in case----make sure you now get your oil changed.


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## merrimacmill (Apr 18, 2007)

I think that mine might do the same thing. When it idles, and I get out and stand next to the truck, I can head almost this creaking sounds comming from the engine. It doesn't happen on a rythem or anything. I just happens randomly. Its not to loud, or a very disturbing sound to me. You have to be out of the truck, and paying attention to hear it. Next time it does it, I'm going to get a video of it and post it up. I've been meaning to get to the dealer about this issue. I don't know if its normal or not, is my first diesel, besides the tractor.


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## cubanb343 (Dec 13, 2007)

merrimac- sounds like you have the same problem i did. i've got an 07 classic duramax, and it was making a ticking noise right near the drivers side front.. i took it to the dealer a couple times and they gave me a printout on duramax engines from GM. they say the tick is normal, and more audible in some trucks over others. their excuse is from the close tolerances in a diesel. i've got almost 15k on the truck now, and the sound is all but gone. not sure if the winter cold makes a difference or not. also, i've changed my oil religiously every 3,000 whether highway miles or not. hope this helps


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## Philbilly2 (Aug 25, 2007)

I use to have that same noise. I fixed it with a stright pipe.


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## Chevy 2500 hd (Jan 30, 2008)

Well Im sure you don't have the same problem as I do I get a phone call today well we just test drove your truck and all the injectors are bad again we tested your fuel and its close to a 50/50 mix water and fuel


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## AbsoluteH&L (Jan 5, 2006)

This may get interesting! I can just see them say that its neglect and not cover it.


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## Chevy 2500 hd (Jan 30, 2008)

my fuel sample no I know this much water has to be due to the fuel station I mean come on how could this much water get in after I filled the truck that friday putting 20 gals in plowed saturday and thats when the problem started. and to think thats just a sample what does the tank really have I should add I have never bought my fuel anywhere else since I have had the truck sure not going back there


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## ABES (Jun 10, 2007)

Philbilly2;537873 said:


> I use to have that same noise. I fixed it with a stright pipe.


That and turning the radio up louder will get rid of any noise/problems


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## Spitz (Feb 28, 2008)

Well thats just in the filter, doesnt mean it all came from one tank.. It could be residual from quite a few tanks.. I drain my filter every couple weeks and always get some water..


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## Chevy 2500 hd (Jan 30, 2008)

No thats a sample the dealer ship pulled from my tank not the filter and plus my engine knock started after running the truck plowing for a bit after getting the fuel and im sorry but you dont get that much water in a tank from residual


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## tuney443 (Jun 25, 2006)

Chevy 2500---You now should report that station to the Bureau of Weights and Measures for their water issue.Keep all your receipts--if you can prove the diesel only came from them,they will be responsible for your troubles.Sorry to hear that,it's not the first time.


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## tuney443 (Jun 25, 2006)

Spitz;538566 said:


> Well thats just in the filter, doesnt mean it all came from one tank.. It could be residual from quite a few tanks.. I drain my filter every couple weeks and always get some water..


You really shouldn't be getting any water from your separator.If you do regularly,there's a problem with water in your fuel source.In more than 140K miles with 3 Dmax's,only once did I see a couple drops of water.


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## Chevy 2500 hd (Jan 30, 2008)

Thats what I was thinking to tuney443 you shouldn't have to be doing that every few weeks thats bs if you do Id be on the case of your supplier asking them to do a stick test infront of you to show they dont have water in that storage tank.


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## Yaz (Apr 13, 2005)

And to make matters worse, you paid close 4 bucks a gallon for that water.

I also never see water in my fuel filter. Duramax's have a built in water sensor in the factory filter... That never went off?


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## Chevy 2500 hd (Jan 30, 2008)

No it didn't I know thought it was odd I had them check it they said its working


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