Injector High Pressure Feed Line Question

[jbplock]

I’m getting parts together to replace all 8 injectors on my 03 LB7. It’s blowing smoke at idle, some balance rates on both banks are out of spec and it holds 160mpa so no special policy for me. My question is, should I also replace the high pressure feed lines? I seem to remember a post by one of our GM Tech members stating that there are improved (SS?) lines that are resistant to galling? I did some searching but can’t find any info. Anyone know if there is an improved line or should I just clean and reuse the originals?

[Jake99Z71]

The answer is YES. Most dealers are replacing them with the injectors.
One problem with the them is corrosion at the connection to the injectors. I've heard some people have tried to clean this up.

[leolkfrm]

withe the extension can't you get the dealer to do a frebee?

[jbplock]

withe the extension can't you get the dealer to do a frebee?

Unfortunately no .. I took the truck in to the dealer and they tried but since it was holding 160mpa max rail pressure at idle it doesn't qualify. Symptoms are smoke at idle, fuel knock and balance rates out of spec - no codes or fuel in the oil.

[OC_DMAX]

How many miles did you get on your truck before the injectors went?


If you buy the lines from the dealer, I believe they are quite expensive. You may want to see what condition your current lines are before expending this sum. Also, I bought a spare set of lines you mention from ebay about year ago (anticipating the injectors will eventually fail - their in great shape for about $50.) So you may want to look over there.

[jbplock]

How many miles did you get on your truck before the injectors went?


If you buy the lines from the dealer, I believe they are quite expensive. You may want to see what condition your current lines are before expending this sum. Also, I bought a spare set of lines you mention from ebay about year ago (anticipating the injectors will eventually fail - their in great shape for about $50.) So you may want to look over there.

Alan,

I started experiencing smoke at idle with balance rates out of spec on 2-3 cylinders at 88kmi. Prior to that fuel knock was more pronounced and balance rates were creeping up.

And thanks for the good advice on the high pressure lines. I had priced new ones and have been watching ebay, but I'm hoping the three water separating filters and Stanadyne Performance Formula (with corrosion inhibitors and water demulsifiers ) used since the truck was new has helped control corrosion. We'll see ..

[Jake99Z71]

Most of the corrosion on the injectors lines is from the outside. A few dealers were putting silicone on the top of the nut on the lines to seal out the outside world. Don't remember hearing if this fixed the problem or not.

[OC_DMAX]

Bill,

You probably had the cleanest fuel of any Duramax on the road. So it looks as if the fuel condition is not the only factor in the LB7 injector life issue. In fact, GM has changed the main fuel filter configuration at least 3 times (as evidenced by obsolete fuel filters sitting on the shelf in my shed).

I wonder what the other issues "really are" with regard to the "median" injector life probably being in the 75K-100K area versus the advertised 200K area when the truck was first introduced. It would also be interesting to know whether GM has addressed fully the issue with the injectors? (though I don't have much faith in GM anymore.)

Having reviewed the posts on various forums where people have replaced them by themselves, it looks like a very doable task, just time consuming.

My 2002 truck is about 8 years old now, with 54K on the odometer. Hopefully, I can make it to 88K like you did prior to replacing the injectors (that would be good for another 3 years).

Alan

[Homesteader]

I'm doing the injectors on my '03 now, same scenario. I took extra care in evaluating the pressure lines and found them to be clean and certainly reusable. A check with a friend at a local dealer indicated it was not the norm to replace these lines on my truck. (I'm in CA and found little evidence of any corrosion) I would recommend that you look carefully at your hoses; coolant and emmission, as these are not usually stocked by the dealers and take some time to get. Also, my valve cover gaskets were pristine and I chose to reuse them. Look them over carefully. Use them if they're not brittle or damaged from removal. You will need all the gasket/seals for the injectors and lines. The injector inserts stayed in place in my case and saved the work of resealing which was welcome. BTW, I popped the injectors out by using a piece of aluminum rod (about 3/16",with an 'el bent for a handle) below the injector retainer as a fulcrum (right under the hold down bolt hole) and smacked the end opposite the injector with a brass hammer to lever the injector out. They popped right up, without prying or twisting. Not a bad job, just lots to do.

[Kennedy]

Not sure that the new lines are stainless, but plated would be accurate. The early ones had green nuts and teh later ones are silver? Been a while since I had new ones in hand, but as I recall, not all part numbers were exhausted of the green ones so that was all you could get.

If you plan to put it together once and leave together or take rust preventative measures I have a few sets of new take off lines. I think a squirt of spray dielectric grease and then maybe inject a dab of conventional grease (melts) followed by dielectric grease to seal it would do well. A simple umbrella seal would also go a long way here. It's just crap that gets down between the line nut and line that causes issues.

The reason for this open interface is so a leak at this point can get outside the engine versus inside. Funny how we have crankcases filling with fuel and no runaway issues etc yet these lines never leak in either direction.

We've been stocking injectors and return line seals etc as we've been doing some engine builds as well quite a few mail order sales as well.

P.S. a demulsifying additive will leave the water free to attack whatever it settles onto.

[jbplock]

Thanks for all the replies . New injectors are in and the truck runs & sounds like new .. The high-pressure lines were in good shape with only a little corrosion on the coupling nut. After watching the balance rates creep up for the past year along with progressively louder fuel knock, decreased mileage, and un-burnt diesel laden exhaust smell that eventually culminated in smoking at idle, I’m sorry I didn’t replace them sooner. However, I confess that I wimped out and let the GM tech at my local dealer do the job. The Tech’s work was excellent. I wanted to do the job myself but with my day job currently consuming all my time & energy, I took the dealer up on their offer to install the 8 GM Reman injectors I purchased from partszoneonline.com (for $213.each including core return freight). Total out of pocket cost was $3200, which I thought was reasonable considering some of the higher amounts others have reported. It’s like having a brand new truck again!

[Spoolmak]

P.S. a demulsifying additive will leave the water free to attack whatever it settles onto.

Please clarify this statement for this novice. I've been using Stanadyne performance additive since joining the forum years ago. Your comment seems to imply there are problems caused by doing so.

I just had the injectors replaced by the dealer, in one day, at their suggestion. (See other post on this). Should I continue using the additive?

Thanks.

Tor

[jbplock]

I've been using Stanadyne performance additive since joining the forum years ago... Should I continue using the additive?

The pros & cons of diesel fuel water emulsifiers vs demulsifiers has been discussed at length in many forums (Stanadyne is a demulsifier) .. For more info google “diesel fuel emulsifier vs demulsifier”

For the record GM’s position is as follows:

"TSB 03-06-04-017D, Information on Diesel Fuel Additives, Dated February 20, 2007

Water Emulsifiers and Demulsifiers:

If the customer desires to use a fuel additive, care must be taken in its selection. There are two common methods that fuel additives use to cope with water in the fuel. One method is through demulsification of water in the fuel. This method causes water particles to combine together to form larger particles, which drop out of suspension. This allows the fuel filter/water separator to separate the water from the fuel as it is designed to. The other method of coping with water in the fuel is through emulsification. This method, often using alcohol as the emulsifier, keeps water particles suspended in the fuel. Emulsification of water in the fuel can allow water to get past the fuel filter/water separator, in most cases causing damage to the fuel system. Only alcohol free water demulsifiers should be used in General Motors diesel engines. GM Diesel Fuel Conditioner(R), P/N 88861009 (in Canada, 88861038) or both *Racor Power Shot Plus® and *Stanadyne(R) diesel fuel additives are alcohol free and utilize water demulsifiers to cope with water in the fuel. Other brands may be available in different areas; be sure that they clearly state that they are alcohol free demulsifiers before use.

TSB 04-06-04-070B, Information on Improved Fuel Filter for 6.6L Duramax(TM) Diesel Engine, Dated March 02, 2009.

A revised fuel filter PN 12633243 is released that will service all 2001-2009 Chevrolet and GMC C/K models and 2003-2009 Chevrolet and GMC C4500/5500 Series vehicles with the 6.6L Duramax(TM) Diesel. The new coalescer filter provides the following benefits / improvements over the existing dual pleat design:
^ 150-200% increase in service life, depending on contaminant type
^ Improved fuel system protection with some premium diesel and B5 biodiesel blends
^ Equivalent coarse water droplet removal efficiency of previous design
^ Greatly improved removal of emulsified water - a major contributor to fuel system issues

Proper fuel filter servicing and the use of clean diesel fuel that is free of water or contaminants are critical for the longevity of fuel system components of a modern direct injected diesel engine. Adherence to the fuel filter change interval will help to ensure that the Duramax fuel system will be protected from contaminants and that the engine will continue to operate as designed. Purchasing fuel from a high volume fuel retailer increases the chances that the fuel is fresh and of good quality.”

[Spoolmak]

Thanks Bill, for clarifying this issue with your detailed and lengthy post!!!!

Having just replaced injectors after 130,000km, I'd like to do what I can to keep this set going longer.

I've replaced fuel filters every 15 to 20,000 km thinking that would extend injector life, but it appears to have made little difference. The new filter design and 2 micron filtering capacity will likely do way more to extend injector life.

What would you recommend? Use the Stanadyne performance additive or not? We live in a semi arid place where we get 10 inches of precipitation a year. Summers are hot and very dry, but winter temps will go down into the 'teens' Fahrenheit and below zero Fahrenheit for a couple of months. I'm not too worried about condensation in the system for most of the year, but could get some water in a fill up, although I go to the highest volume gas station in town. I've never had any fuel issues like 'gelling' or no start, and at my filter changes I've never had any water in the filter base.

Thanks,

Tor

[jbplock]

Tor,

Since my truck was new I’ve used Stanadyne Performance Formula and a Lubricity additive (started with TCW-3 2-cycle oil then switched to Stanadyne Lubricity Additive). I also installed a 2u JK Mega Filter post OEM at 6k miles then a Pre-OEM 30u Stanadyne FM100 pre-filter with Lift pump at 9kmiles. The OEM & pre-filters have been changed regularly at 10k mi or less and I’m currently on my third Mega Filter. When changing filters the only one I ever find any free water in is the 30u pre filter and that is only 1 or 2 small drops if any – never any water in the OEM or Mega Filter. Even with this my injectors failed at approx 88k miles. So my personal conclusion is that clean fuel and regular use of additives alone, while beneficial, won’t prevent injector failures.

[Spoolmak]

Bill,

I think you've nailed it. Despite our efforts to protect the fuel system, the injectors fail quite early.
I'll continue to use the Stanadyne and change the fuel filters even more frequently.

Thanks for your advice.

Tor