Diesel Place banner

1 - 20 of 24 Posts

·
Registered
Joined
·
245 Posts
Discussion Starter #1
OK I'll go with this only because I have never seen the procedure....


What keeps you from changing out the injectors yourself?


What does it entail? I guess a ton since everyone sends it the dealer, even out of warr. ones, to have them fix it?


TIA.


cmc
 

·
Registered
Joined
·
994 Posts
Not answering your question directly, but the vast majority of the vehicles are still under the 5yr / 100k mile warranty. I suspect as more move out of the warranty period, we will start to see more questions like yours. Give it another year.


I would think if your mechanically able, you have the right tools and ask Eric (Dmaxallitech) or others what the pitfalls are, it should not be a problem. Look in the Tech forum. I think Eric answered a question like this maybe three months ago. If my vehicle was out-of-warranty, I would give it a try.
 

·
Registered
Joined
·
909 Posts
One of the big pitfalls is debris falling into the injectors. There's a bunch of gunk just waiting to fall and even the techs appear to be having problems. Perhaps this accounts for some injector repair return visits.
 

·
Registered
Joined
·
692 Posts
not all that hard i always psi washe a rig before opening the vlv covers. its all nuts and bolts and seals and gsks. the injector removial tool helps to remove it.
always be carefull with the wiring and just remember not all fuel leaks are injectors.. you may do a ton of work and not fix it
 

·
Registered
Joined
·
138 Posts
Hi Chris (CMC-GMC),


I asked Eric (dmaxallitech) about this a few months ago. I believe it takes Eric the better part of a day to do this and he is really, really good at it. So, eight hours labor, minimum, plus $400-$500/injector really adds up quick. Man, do we need an aftermarket for those injectors!!


I've rebuilt numerous gas engines, rearends, and even tackled an automatic or two. No, not a mechanic. I was just a poor Airman in the Air Force without two nickels to rub together, but a pretty good sense of how to take things apart and put them back together.


I can't remember the last time I took a vehicle to the dealer for ANYTHING. I think I took a Jeep Cherokee in for a recall on the "sudden acceleration problem" (idiots mistaking the gas peddle for the brake pedal actually)!


Been collecting some thoughts (and great pictures-thanks Hoot and Eric) on what this will take when the time may come..... probably around 100-200k:


Best tip so far. That clever Eric removes the front tires and sets the front end down on the ball joints. Sure makes working on it a lot easier.


If you don't have a digital camera, get one! Take lots and lots of pictures so you can get things back where you removed them.


I believe the only special tool needed is the one needed to pull the injectors? Part #?


Carefully, very carefully remove those fuel lines where they attach to the injectors. I HAVE NOT seen ONE picture that doesn't show a lot of crap inside those fittings. It's metalic!! Attention Chevy/GM, I'm an engineer now. You have serious, serious material incompatibility here that is causing metal to migrate off the ends of the fuel lines due to galvanic action. Based on what I've seen, replace those lines. I wouldn't reuse them. You'll really need to spend some time and CAREFULLY, very CAREFULLY clean that metalic crap off of the top of the injectors. I, too, believe that a lot of the nearly immediate repeat failures are due to that crap falling into that open top of the injector.


If this whole thing takes me a week, or more, so what. I'm coming up on retirement real soon now!
The only thing I use my Dmax for is to haul my fifth wheel to the next fishing hole.
 

·
Registered
Joined
·
6,504 Posts
I've been thinking about the galvanic corrosion question and it's certainly a strong possibility. The steel high pressure line, line bushing, nut and connector body may be producing a potential due to differences in the metals, but they're all steels - so that seems strange. I had a thought about the voltage and amperage applied to the injector solenoid and if that is a contributing factor. the injector solenoids are two-lead, but are they both power leads and the injector grounded through the body/head? If that's the case, there could actually be some arcing going on in the connector.
 

·
Registered
Joined
·
994 Posts
Injector cost and part number:



<TABLE cellSpacing=0 cellPadding=3 width=567><T>
<T>
<TR background="images/trans.gif">
<TD class=reg vAlign=bottom>GM PART # 97720661
CATEGORY: Fuel Injector
PACK QTY: 1</TD>
<TD class=reg vAlign=bottom>CORE CHARGE: $100.00
GM LIST: $530.90
OUR PRICE: $265.45</TD>
<TD align=right><!--< name="p97720661" ="text" value="1" size="2" maxlength="3">
< ="" name="parts" value="97720661">--></TD></TR>
<TR vAlign=top background="images/trans.gif">
<TD class=reg colSpan=3>


DESCRIPTION: INJ REM K
</TD></TR></T></TABLE>above is from GM Parts Direct - $264.45
 

·
Banned
Joined
·
394 Posts
EBAY 50 BUCKS EACH.....PRICELESS
 

·
Registered
Joined
·
1,005 Posts
Ref core charge, looks like they're rebuilding them now
 

·
Registered
Joined
·
994 Posts
Ref core charge, looks like they're rebuilding them now


According to Kennedy and Eric they are still new even though marked REM. Maybe just collecting the cores so they don't end up in aftermarket and drive the price down (who knows?).
 

·
Registered
Joined
·
1,309 Posts
Two wires on the coil equals one + and one - .Later! Frank
 

·
Registered
Joined
·
1,349 Posts
Patrick, or anyone on here, Its my understanding that the new Duramax is going to have external injectors, are any of you familiar with these, does this mean that that will be easier to change out if they go bad, there by cutting down on time and labor cost?.
 

·
Registered
Joined
·
245 Posts
Discussion Starter #13
Just wondering guys thanks. I've been a back yard mechanic for years but hung up that hat when I bought the 02 and sold my vw toys. I've built tons of VW engines, a few gassers and rebuilt transfer cases 4 spd. sticks (dodge). I just figured maybe there was something I was missing in the procedure. Just looks like a real big job with some special tools. Done stuff like that before. (refer to vw engines :)


I'm just lucky I got the 7/70+K warranty and a shop supervisor that said no matter what I was covered with my injectors... hopefully I'll never need either of them.


later


cmc
 

·
Banned
Joined
·
6,539 Posts
Here is the injector with only the upper valve cover removed. Notice the corrosion on the fitting....


Here are the injectors removed with the removal tool laying along side. It's basically a lever that pulls up on them to suck them out of the cup. The middle pin goes in the injector bolt hole after you remove the bolt. It uses the injector clamp as a lever.


BTW: The tapered portion of the fittings are a different steel composition it seems by the color difference. They are magnetic so it is steel. Thing is they don't corrode at the fuel rail but corrode terribly on the other end where they contact the injector.



Edited by: hoot
 

·
Registered
Joined
·
6,504 Posts
Frank Blum said:
Two wires on the coil equals one + and one - .Later! Frank

Well, two wires of the SAME COLOR on the injector equals two + and engine ground. Perhaps one is pilot injection signal and other is full injection signal? Have to check the service manual tonight! Good photos, Hoot! Really shows "up close and personal" what had to be done on the LLY heads to move those injectors out. That level of corrosion INSIDE the oily environment of the valve cover is pretty scary!!
Edited by: Idle_Chatter
 

·
Registered
Joined
·
138 Posts
Hey Idle, we're on the same wavelength here! I think some others are also with regards to stray currents.


Hoot, did you say there is "magnetic" material in the injectors or just that it was steel that would attract to a magnet?


The reason I ask is, everyone knows that to generate electricity you swing a magnet through an electric field. I don't know what the current/voltage are going to the injectors, but you can bet it's a pretty healthy shot to move that pintle as fast as it does. Even a slight bit of magnetism in that pintle would generate a current in the body of the injector that would have to go somewhere. Perhaps through the fuel line??


What you're seeing on that pitted fitting LOOKS exactly like what happens to ball/roller bearings in jet engines, centrifuges, etc when an electic current is run through them for a LONG period of time.


Been there done that. We had a centrifuge with an eight foot arm that we used to test "things" with. Just swinging that arm through the miniscule magnetic field of the earth was enough to cause the same sort of pitting in really, really expensive roller bearings. The FIX was simple! Add a slip ring and brush across the bearing to carry the stray current.


I may have to dig out the scope and do some snooping.


Hmmmmm
 

·
Banned
Joined
·
6,539 Posts
No the metal itself is not magnetic. It does attract a magnet though.

The reason the corroded end looks like a pitted bearing is because I ScotchBrited the loose flakes off. Those pits are the results of stationary corrosion, not the wear pits produced by bearings rolling on races.

Notice the very tip portion is not corroded. That is the part that makes the seal. It doesn't corrode there cause its in contact with pressure from the tightening of the fitting. I believe the lines can be reused and will seal ok because they only seal at that small uncorroded portion.

Also... for the do-it-yourselfer....

Getting the parts cleaned up is no big deal. It just needs to be done prior to reinstalling the parts. The bad news is you have to remove ALL of the injector feed lines on the side in question just to remove the valve cover. This exposes All four injectors to contamination so it is important that any injectors not being replaced have the fitting end sucked clean with no chance of that corrosion falling into the fuel port.

Also.... those short injector feed lines either need to be replaced or meticulously cleaned if you reuse them.

The return line is one piece so it has to be disconnected at all four injectors and at the fitting where it enters the head galley.

Now you see why they redesigned the head. So you can service one injector from the outside without disturbing the others. Edited by: hoot
 

·
Registered
Joined
·
218 Posts
If someone could use a Multimeter and see if there's any stray current cruising around those injectors I think you'd be able to make the case of galvanic corrision. Problem is, how the heck do you do it when the I believe you need the truck running and the valve cover off to use your test leads. We're talking dissimilar metals here that cause galvanic, magnetic would produce electrolysis, both only need millivolts.....I think it only takes around 400-700 of those suckers to start the whole process depending on how noble the material is. I'd say electrolysis if anything. By the way, from the picks, it sure looks like galvanic or electrolysis from what I've seen in the boats.
 

·
Registered
Joined
·
994 Posts
It looks like each time you go to replace one bad injector on the LB7 design, you have to disconnect both the feed and return lines to all four injectors on one side. I think if my truck had say 120K miles on it and an injector went out, I would seriously consider just replacing all four injectors on the one side at the same time. Otherwise, as each injector fails and replaced, you risk contaminating the other three when things are taken apart.


The LLY design looks attractive. Lets see what Eric thinks when he takes the first one apart!
 
1 - 20 of 24 Posts
Top