New here

[SeanWright]

Hello all...I'm new here and new to Duramax engines.

I have been a mechanic all my life (a pretty good one if i say so LOL); my diesel experience is on old road diesels....Cummins big cam series and old Macks. Not much experience with these new pick up diesels.

Thats what leads me here.....just got an 04 6.6 duramaz that is making a hell of alot of noise, sounds like valves to me, and is very sluggish....any ideas on where to start or what to check first?

And before anyone asks, i have not been able to pull the codes yet, will do so tomorrow sometime.

 

[blue09dmaxx]

Injectors

 

[SeanWright]

I was kind of leaning that way myself.....any tips on testing them? Anything special i should look for?

 

[zakkb787]

First off fill out your signature so we know why truck you have and what's done to it etc. second if your truck an LB7 or LLY? If you're not sure the. Look at you're VIN. 8th digit is a 1 if it's a LB7. 2 if it's an LLY. As for testing injectors. Find someone with a scan tool that can read diagnostic and find your injector balance rates. Spec is +/-4. If they are out of this spec. You need injectors. I recommend Lincoln Diesel Specialties. They are a vendor here and can hook you up with what you need for the best deal. Steer away from the eBay or Pensacola or other cheap injectors. You'll thank me when you don't have to change them in 5k miles. Again. If it is injectors. While you replace them do some preventative maintenance/modding. Get new or used cleaned injector lines. Get a lift pump. I like Kennedy pumps but there are others. If that's not in the budget at least swing for a cat filter adapter with either the 2 micron CAT filter or 1 micron Baldwin. Filtration helps injector life.

 

[Mike L.]

Welcome.

 

[TLyons90]

Welcome! As said above find someone with an EDGE CTS or scan tool that can read balance rates and have them check them. Good chance that if it is an LB7 the injectors are bad and whats causing your issue if they have never been replaced. Check your oil as well for any kind of fuel smell.

 

[SeanWright]

Welcome! As said above find someone with an EDGE CTS or scan tool that can read balance rates and have them check them. Good chance that if it is an LB7 the injectors are bad and whats causing your issue if they have never been replaced. Check your oil as well for any kind of fuel smell.

I have a scan tool just haven't got around to reading the balance yet...

I have a 2004 1500 4 x 2 LLY 154000 miles. The truck just had the valve springs replaced in it right before i got it. The truck is all stock except for the recent valve springs.

I am pretty much leaning towards the injectors and cups. Gonna look at the balance, the possibly do a compression test, then maybe pull a few injectors and look at cup condition and look at fuel line conditions.

At this point i am not adverse to replacing cups, fuel injectors, fuel lines, and upgrading to a CAT filter.

A friend had just about the same issue and his was the injectors.....have to wait and see when i get time what things are really looking like

 

[zakkb787]

If your valve springs were replaced recently most likely what happened was when the lines were cracked open dirt and debris fell into the injectors contaminating them. Same thing happened to me. IF it is an LLY like you say they do not have injector cups. IF it is an LB7 you do not need new cups. Just need to extract them. Clean them thourougly. And reseal them with red loctite (don't remember exactly what kind but it's the strongest they make) and new o-rings. If it's just a few bad or out of spec I'd recommend going ahead and replacing them all at that mileage especially if some are failing already.

 

[Awenta]

Use sleeve retainer on the cups if it's an lb7 and don't bother with a cat adapter and filter.

If it's a lly it's probably injectors too.

Post a picture of the engine

Why would the valve springs have been replaced?


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[zakkb787]

Use sleeve retainer on the cups if it's an lb7 and don't bother with a cat adapter and filter.

If it's a lly it's probably injectors too.

Post a picture of the engine

Why would the valve springs have been replaced?


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Just curious. Why advise against extra filtration?

 

[SeanWright]

Just curious. Why advise against extra filtration?

I will post pictures later...no where near truck now.

I was wondering the same thing...always been my thought the more filtration the better. Plus i can usually get the CAT filters as freebies on a job site.

 

[JRein]

They changed the design of the filter and it now filters the same as the CAT filter. I have a CAT because I don't want to spend $60 for an AC Delco. I'm also running a 30 and 10 Micron before it so it spreads out the filtration.

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[zakkb787]

They changed the design of the filter and it now filters the same as the CAT filter. I have a CAT because I don't want to spend $60 for an AC Delco. I'm also running a 30 and 10 Micron before it so it spreads out the filtration.

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I had heard about that. IMO I'd rather have the adapter to pay less for a filter and option of even a 1 micron filter later on. Filtration as a big key factor in keeping injectors

 

[1ATony]

Welcome to the site it's great to have you here

Tony

 

[Awenta]

Just curious. Why advise against extra filtration?

Because they don't have a water separator. And that will kill a system in short order. Also they're most likely closer to a 4 micron but there isn't any actual absolute or nominal ratings available so we'll never know.


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[WVRigrat05]

That's why you slap a F/W separator on the frame somewhere, I never hooked up my sensor anyhow, unless you keep that sensor replaced every so often there don't work any how.

I run cat 0749's on mine, I can get 3 of those big bastards for the price of one stock filter and it filters a little better and so far they last longer due to the extra surface area.

 

[JRein]

That's why you slap a F/W separator on the frame somewhere, I never hooked up my sensor anyhow, unless you keep that sensor replaced every so often there don't work any how.

I run cat 0749's on mine, I can get 3 of those big bastards for the price of one stock filter and it filters a little better and so far they last longer due to the extra surface area.

Like he said. Also I run my W/S on the suction side as all filters I've looked into are rated as such. Water is most likely to fall out under suction and once it is ran through a pump it becomes emulsified.

Different filters rely on different ways of seperation ranging from repelling or absorbing to simply using gravity.

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