So i finally found and purchased a new (to me) work truck. It is a 2004 Chevy 3500. The bad news is that it has a fuel knock. I am guessing that one of the injectors is bad or plugged.?. I just threw a dose of Lucas fuel injection lube/ cleaner in the tank. If that doesnt work does someone know of a good fuel additive to clean the injectors or know how to isolate which injector is bad??? It is very easy to see the truck was NOT well cared for.... but the price was right (i hope) :Banghead I will post some pics when the weather is better. Thanks
you can try checking the exhaust manifold with a heat gun if you can get to it. the cold one would be the bad one.
The Duramax has 2 different engines for 04. The LB7 & the LLY. The LB7 is notorious for injector problems. The way you tell which one you have is the 8th vin # is a 1 for the LB7 & a 2 for the LLY. For good forums go to Duramax diesel foums or the dieselplace.com.
check the wireing harness on the 3or4 injector there was a recall on the harness it was to short and was pulled into also the additive to use is the stanadyne treatment it is recommened by the manufacter alsoif you know someone with a scanner it will tell you witch one is badnot firing
thanks for the info, the duramax forum helped confirm my suspisions. Apparently GM extended the warranty for this issue. I am going to take it to the dealer and see what they say. I am guessing the injectors are going to need replaced thanks!
I wish you luck on the warranty.The Injectors are not cheap.
The warranty is only 7years or 200K from the purses date, so most likely your to late. They don't always cover 03 and 04 since GM "fixed" the issue in 02. A fuel knock isn't a normal sign for bad injectors. You will have white smoke at idle when its warmed up and you will gain oil because of the fuel. You can smell and see fuel in oil. Put a drop of oil on a paper towel. If there is fuel in it you will have a dot of oil and then the fuel will spread out further making a clear ring. I don't know where your at in OH but there is a damn good diesel shop in Zeeland, MI called Merchant Automotive if nothing else he can help you out with parts ETC. Good luck
Well what is a sign of a fuel knock? I am having black smoke, in fact it smokes like a train when you accelerate! I called the Chevy dealer today and they said there is no warranty remaining on my model (suprise surprise). With that said, i dont want to buy an injector if thats not the problem???? So what is???
Are you getting a CEL? IF it does go to a local parts store and barrow a scanner. Does it run fine other then knocking and smoking? Do you know if there is a tuner on it? Your probably going to have to take it somewhere to have it trouble shot. I would avoid a dealer it you can there big $$$.
Most parts stores will do this for free.Dealers here charge you $100 just to scan it. unless you let them repair it and stick it to your wallet.
Yes, i took it to autozone the first day i got it because the check engine light was on. The code was a faulty MAP sensor and a possible vaccum leak or something. I cleaned the sensor and that made the engine light turn off. The truck runs great other than the smoking and knock...... so thats were i am scratching my head, it has to be a fuel problem??? Maybe bad injectors, maybe a injection pump not set correctly?? I just dont know that much about the problem being that its running strong. :Banghead:Banghead:Banghead Anyway have a merry Christmas everyone!!!
Is it knocking all the time or just at idle, ETC? Cold and warm too. It could be from numerous things senors, injection pump/regulator, and a tuner too. I don't think its injectors unless you have some of the above mentioned signs.
It knocks and smokes whether warm or cold. It only does it bad when there is a load on the motor (in gear)
Barklee-I would go to a mechanic with a much better scanner than Autozone or Advance offers--ones like the $5K Mac and Snap-on make.Otherwise,it will always be speculation.
Fuel knock and excessive smoking condition is one of the typical injector failures found on the early Duramax engines. You need to figure out which side of the engine the faulty injector is on. With the dealership scan tool (Tech 2) you observe the injector balance rates. The cylinder that is at fault's rate will be off the chart. It's not uncommon to find most of the injector balance rates on the outs. Under warranty if 1 is out, you do all 8. Used to be you would do all 4 in the same bank as the faulty 1, but the truck would be back within a few weeks with 1 down on the otherside. I would have to advise at least doing the whole bank. One thing to note on this engine, #1 cylinder is the right front, not the left front like every other Chevy. Depending on which engine you have (LLY, LB7, LB9) the job can range from not to bad to not so much fun. Take a look under your hood. Look at one of the valve covers. Do the injector lines go through the cover (internal injectors) or do the valve covers go around the injectors (external injectors)? If you have external injectors your laughing. Takes a little work to get to them, but it's straight forward. If your injectors at internal style (most common to fail) then your in for a little more of a job. The job is not really that bad, just time comsuming. There's a lot of stuff that you have to move out of the way to get the valve covers off. None of it is that difficult but it just adds up. Do yourself favor and snap a few pics before you dive in to far. There's a lot of lines and brackets that only fit 1 way together and having a picture for reference will help when it comes time to put it back together. The fasteners on this engine are metric. They like being metric, and they do not take kindly to being mistreated with imperial tools. The valve cover bolts are 5mm hex bolts. Your going to need a good fresh (not worn) socket with a flat end, not the ball end type. Make sure the bolts are clean of debris, and give the socket a few sharp raps with hammer and break the bolt free by hand. Once it's loose you can go at them with a air ratchet and a ball end socket all you like. The valve cover bolts will strip very easily otherwise. Trust me, i speak from experience. Speaking of experience, if you do manage to round off the v/c bolts, take a 12pt 3/8" socket and pound it over the head of the bolt. It will grab onto the outside of the hex and will usually remove the damaged bolt. You will have to replace it however. Another fastener to be mindful of are the injector lines themselves. They like to seize up on the top of the injectors. They are 19mm. If you cannot break them free with a good line wrench, and you think they are going to strip then your better off to cut the line off and use a socket to remove the fastener from the top of the injector. The lines are pricey, but there's not much you can do. If you strip them your really in trouble. There's a special tool to remove and install the injectors. You don't really need them if your resourceful. Make sure you replace all the seals for the return line rail. The injectors each have a code on the top of them that will need to be programmed into the ecm when replaced. It's the flow rate settings for the individual injectors. It will run fine with out the reprogram, but can set an engine light. Good luck, keep us updated and I will try to help you out best i can.
That is great info waterdoc! I took it to the dealer today and they said the #6 injector is bad. I have the LLY engine and it doesnt look too bad to change, other than moving a few lines and harness out of the way. Have you found that the injectors like to seize in the motor? I did a deutz enigne this summer and it took me and a good mechanic 4 hours and a torch to remove the bad injector! The guy at the dealer said they arent bad to do but to drain the coolant because the sleeve likes to pop up with the injector and it will dump coolant right into the motor! He also spoke of that special tool to remove the injector, can you explain how to be "resourceful" so i wont need it? They said they might let me borrow theirs but i didnt buy the injector from them so i doubt it. They wanted $485 for one and you can buy them from a local diesel shop for $250! I went even cheaper than that and bought one at a junk yard for $70, hopefully it will hold up. It only had 40,000 miles on it. Anyway thanks for the info
LLY? your in good shape then. I've never had an injector that wouldent come out of a Duramax. This is the special tool for injector removal http://www.usatoolwarehouse.com/usatoolwarehouse/OTC-J-44639.html I don't like it. It pry's out the injector but it also puts alot of sideways force on the injector while doing so. This is why i think you get the sleeve coming out with the injector when using that tool. Using my homemade puller i only pulled out 1 or 2 out of over a hundred. My puller tends to pull much more in line with the injector. The puller I made is really dead simple, and i bet alot of people already have something like this. It's a small slide hammer. I took an old injector line nut (one that i had to cut off and use a socket to remove from the injector). I welded a 1/4" nut onto the top of it. I have a weight made from 1.5" round stock with a hole drilled down the center and its' about 2" long. I run a 4" 1/4" bolt through the weight and into my injector adapter and voila one slide hammer. I also have a smaller weight and shorter bolt for use on the C-Series truck since the back 2 injectors on the drivers side are a real joy for access. I have a few different injector ends for different engines. Draining the coolant on those trucks is nice and easy. There's a draincock on the rad. Just take care not to bend any of the lines out of the way when you go to do the injector. It's tempting but they never sit right again or the fittings leak. Put the extra effort in and take them all the way off if needed. Be patient and gentle with the fuel return lines. They can be finicky and can break if forced. Best of luck!
you might try running some kind of diesel fuel treatment to add some lubricity back to the low sulfur diesel the stuff is so dry it can cause some injector issues as well as possible inj pump I was using Lucas and now am trying some Howes as it is cheaper as you do not have to use as much.Just a thought
You've got the external injectors. You lucked out. Never had a problem with injectors seizing into a Duramax. Definately drain the coolant out. There's a drain **** on the lower left side of the rad. It's a white plastic piece that you put a 1/4" drive extension into. http://www.usatoolwarehouse.com/usatoolwarehouse/OTC-J-44639.html That's the special tool for removing the injectors. I don't like it. You engage the fork end into the injector and then use a wrench on the hex side to pry up on the injector. I found that this tool likes to pull the cups out with the injectors since it also put alot of side load onto the injector as it pulls it up. My home made tool is quite simple really. It's a small slide hammer made out of an old injector line nut (saved from one of the ones i had to cut off) with a 1/4" nut welded onto the top of it. A weight and a 4" 1/4" bolt. I also have a shorter bolt and smaller weight for the hard to access injectors in the C-series trucks. This tool will pop out duramax injectors with 2 good whacks. It pulls the injector up with very little side load and because of that I almost never have the cup coming out with the injector. The external injectors have fuel return hoses rater then a common pipe. Be careful with the clips because they are plastic and easy to break. Not much advice here other then to be gentle. Also get a hold of the torque values for the injector hold down and follow them carefully. They are lower then you would think since the head is alum and it's easy to strip the threads if your over zealous. Good price on the injector, i remember when they were over 1g each. You will have to get the injector trim programmed at the dealer afterwords but it's not critical. Good luck!.. take some pics and i will see if i can remember anything else that you could use.
Oh just a note for others on this subject. The pump on a Duramax has no settings. It's a common rail system and it's just a high pressure fuel pump. It only goes in one way and it's not a nice job to swap out.
I'm really surprised it was an injector. There is a forum called Duramax Diesels and it has some of the most knowledgeable Duramax guys that there are there. ULSD isn't that bad really but an additive never hurts. The best thing is Bio diesel I buy 100% bio and mix in 2% when I fill up and thats alll you need to get the most lubricity that you can. Howes isn't very good really for lubricity IIRC, but its great for gelling. Cheap walmart brand 2 stroke oil mixed in at 1pt per 26 gal. fill up is another cheap way to get really good lubricity too.
Thanks for all the help and info! I cant wait for my new (used) injector to get here so i can tear into this. I ran a bottle of Lucas injector cleaner through the tank and i bottle of fuel conditioner. Have you guys ever heard of running tranny fluid in your fuel? An old trucker said thats what he did, but i never tried it.
It was ok back in the day but not today with friction modifiers and CR diesels.
Tranny fluid works good on galled Cummins Inj.Ran one about a week with it.Injectors never seized but when the diesel lost its red color look out.But now days too if they check diesel for red dye and seen tranny fluid which is red.It could cause you trouble with the big boys. But I have never heard of any body being checked.
I heard of a guy that got nailed leaving the Houston rodeo, but they let him off after showing then the bottles of ATF. Thats what I heard anyways and it was one of those friend of a friend stories.
I did hear of one at a Cattle sale.Driver was nailed and Boss had to bring money for the fine yep he got nailed too.I think they can check to see if it's dye or not.If they want to that is.
Just got my injector in today. Gonna try and install it in the morning. I will try to post pics of this project
That was not as bad of a job as i imagined. The worst part was dealing with and trying (to no avail) to move the harness that runs right over top of the injector. In the end i loosened the harness as best as i could and jockey the injector out and back in around it. Whole job took about 4 hours but would have been about half that if i didnt screw around with the harness. I ended up losing the clip that holds down the return line. I bought one that was close from the auto parts store so i hope it stays put! I used a mechanics pry bar to remove the injector and i poped right up. I appreciate all the help! :notworthy
Have you started it yet?Did the injector help?Ron G
Not 100% sure yet. I painted the body right after the injector so i havent had it out on the road yet. I did let it idle in the shop for about a half hour. It seemed to be running better, there wasnt the miss that you could hear before. Crossing my fingers, i should have everything done tomorrow and get it on the road
I like chevys
I forgot about this post! I got the truck done and on the road now. When i was taking out the old injector i lost the clip for the return line. It was Sunday so i went to Autozone and bought the closest thing i could find Which was a window clip. Needless to say that didnt work and kept blowing off the return line. That Monday i went to a local repair shop that works on big trucks and they happened to have a small box of used ones, so they just gave it to me! The dealer wanted $28 for one clip. Anyway everything is so far so good. That seems to be what was wrong the whole time. I guess we'll just cross our fingers and hope nothing else falls apart. Overall the job wasnt that hard, the worst part was moving and keeping the electrical lines out of the way. Whole job minus the missing clip fiasco was about 4 hours. I have average mechanics skill so i would say most people on this site could do the job no problems.
Hi WaterDoc: finally some one who knows what there talking about , I need some info on a 2004.5 Duramax ,I am having rough idle at low rpm and a funny smell , I believe it is a bad injector or the fuel rail pressure regulator . How do I tell which injector is bad and how do I change them ? Can I clean them and how ( ultra sonic ) wire brush ? Thanks for any help
I need some Help from you Can you help me with my 004 .5 Duramax I have a ruff idle it seems liker the engin wants to take off a idle it is noticable up to 1500 rpm then it aseems to run fine and this problem seems to come and go but is becoming more and more apparent' Think it might be an injector how do I tell and then How do I tell which one and where can I gt them in Canada at a resonable price ?????? HELP
I know some people that have gotten stuff from here and they do great work. http://www.kennedydiesel.com/
Your going to have to take it to a shop to have it trouble shot. You have external injectors like Barklee and you need to replace them just can't clean them. I'd don't know of any diesel shop up north to recommended.
We need some more information about your problem and truck. - Any dash lights on? If so, which one and is it on all the time or only when the problem presents it's self. - What is the miliage on the truck? - When was the last time the fuel filter was changed? - Any abnormal smoke? or only the smell - If you shut off the truck, wait 10 secs and start it again does it still idle rough or is it back to normal? - What is the fuel quality like? The problem that you seem to be having could be any number of things. Unfortunately you will more then likely have to take it to the dealer for a diagnostic. Theres really no good way of zeroing in on the issue with this engine unless you have a tech2 scanner. I don't know of any good shops on the west coast unfortunately. However, if you get it scanned and get a diag and post the results i can help you out and give you some guidence from that point.
I think the diagnostic i got was only 75 dollars. It was well worth it, i spent over a day try to figure out what was wrong and which injector was bad!
Hello WaterDoc, Seeing this is an older post, I am hoping you are still around. Newbie here as I just registered. Could you please message me as I am unable to inbox you? Thank you for your time!
Melissa, once you post 3 times, you'll be a junior member, and will be able to PM members. The best idea is to start a new thread if you are having mechanical problems, because there may be more than one here who can help you. You can go to a test forum and post twice more, then log out, wait a little while, log back in and you should be set. Good Luck
What can I help you with Melissa?
Thank you, Mitch! ;-)
WaterDoc and/or Mitch504, Due to my ignorance, I wasn't aware of "recall" on the injectors on my 2004 Chevy with 60K miles. Because of the smoke coming out of the muffler, I took it in to the dealership that I had originally purchased it. My dually has 3 bad injectors and the cost of the repair would be $2,865.02. They suggested that I replace all 8 and the cost is $4,748.02. I am VERY disappointed at the repair cost! I don't even owe that amount on the dually! I was able to work with a GM Executive office and they are willing to pay 50% of the 3 bad injectors but not all 8. It's still a disappointment that I couldn't get the whole cost taken care of. From reading all the negatives on the dually, I've come to terms and just sell it outright! (I hope I can sell it!) I'm at a lost... 1. Do I just repair the 3 bad injectors only and call it good? 2. Or dig deep into my pockets, replace all 8 and hope that it doesn't happen again? Also, I drove my truck home without the repair. Will I do any further damage if I drove an additional 80miles to get it back to the dealership? Thanks for your time and any input that you may have!
Yes you could. Check the oil first if its WAY over filled drain it and refill it with some cheap delo 400 don't bother to change the filter. The reasoning is bad injectors flood the cylinders with fuel and it gets into the crankcase with the oil thinning it out. IMO find s local shop the works on diesels and has experience changing out injectors on Dmaxs and take it there dealers charge an arm and a leg. The injectors will fail again there no telling when but I'm sure you could get another 60K out of them. Swapping out injectors isn't that bad on the 04s its just a bit of work.
Working on a 6.6 duramax alberta canada.......injectors siezed hard,,,,,,Had to pull with slide hammer and found upper o-ring cut from installation,,, ***?????
We sabotage all Dmaxs before we send them to you northerners.
I think the injectors are pre-sabotaged from the factory!! PITA is an understatement..