The discoloration on the fuel-side of the injectors is what they are talking about. Turns out the a-holes see that and now automatically deem the injectors as 'junk' and 'not rebuildable'. What you see on those injectors is polymerized VO and/or biodiesel. While this stuff may be a PITA to clean off, it DOES NOT mean the plungers/barrels/stop plates/etc are 'eroded' or damaged. Yeah, I'm kinda pissed... I think these guys have probably seen enough 'alternative fuel' injectors that have this kind of damage - but to automatically throw out any injectors that 'look like' they have run VO is BS. The damage to VO injectors is typically caused by a caustic restaurants use to clean the fryers after the dump the oil. They often dump this 'washwater' in with the used VO. WVO contaminated with this caustic solution can/will/does do catastrophic damage to the injectors. I have seen torn-down injectors with this damage and got smart really quick about what causes it. Since I don't 'dumpster dive' or steal WVO - I know exactly what I'm getting and there is no caustic in MY fuel. I have sent a couple sets of injectors in (to different builders) that worked ABSOLUTELY PERFECTLY and was told they are useless. I found out recently they made this determination within 1 second of unwrapping the first injector. I can almost guarantee I could have put these back in my truck and run another 100k miles or more - but I believed they actually tore my injectors down and saw an eminent problem.

Stepping off soapbox now, please continue with your regularly scheduled program....

 

Coked injector tip:



All (8):



This guy was running WMO. Truck smoked like a steam locomotive after running WMO for awhile and he pulled injectors and found this...

 

What great feedback! Basically, I've learned I don't want a piece of bio just yet and I waited a little too long to swap sticks. I also know the perils of WMO and forgetting that copper washer. This was the goal for starting this thread. Any other stuff out there? I've seen pictures in a PDF of rust from cracked cups leaking coolant.

 

If combustion gasses were leaking past the copper washer then I'd suspect the washer would be consumed or heavily damaged. The lower o-ring should show signs of heat damage as well...

My guess is slight fuel seepage past the lower o-ring while the engine is at rest. Then it burns or cokes when the engine internals come up to operating temp. If you look at the o-rings on the older injectors you will see they are fairly black and the original orange colored coating is gone. At one time I used to think the OEM o-rings were all black and just the replacements were colored but now I am not so sure. I think maybe the OEM o-rings started out with the coating and eventually that wears out as the operating hours accumulate.

I'll try and find a photo of injectors from my recent swap...

 

Love the thread, good Info

 

purdy injectors!

 

The pic I posted of combustion gasses leaking was due to injector(s) not fully seated. The hold-down collars hit the studs and prevented them from holding the injectors adequately. Yes, the copper washers were FUBAR on those cylinders. Also, besides having poor compression in the cylinders, there was lots of air in the fuel after making any boost - needless to say, the engine didn't run so good........

 

I've been told it makes a crazy sound when injectors are loose...is that true? I imagine they would be sucked down and seated during the intake stroke and then pushed up during the compression stroke. Probably then would make a heck of a knock during the power stroke......

 

Ooo.... I'm glad you brought that up! I forgot I had an old file on the two bad injectors I replaced. Does anybody know what is wrong with this injector?

 

This is a good thread with lots of pics to help a dummy like me when it comes to injectors.

 

I am so with SSJ on this. I think it is a lame excuse to deny credits (if the owner doesn't run diesel, turn him away).
A lot of vo residue can be washed off using ethanol (E85 works great) and elbow grease.
Sorry, no pictures at this time.

 

I don't think these actually moved up and down, but definitely did not seal with high CP's. It ran pretty good until about 15psi, then missed like hell for awhile - I guess until the air got worked out of fuel/oil... Eventually, enough fuel leaked down on top of a piston to hydrolock it. Turns out I can swap a set of injectors at camp a few 100 miles from home!!



Thinking about it though, there isn't too much 'suction' on the downstroke since the intake-side of a diesel is wide open.

 

Bump . . .

 

How about we get down to the nity gritty guts of the discussion...

Some guts

This is what wear looks like:

Significant shoulder wear on the poppet valve sealing surface.

Significant wear at the valves return positionin face. This is a big part of that .000-.004 gap between the armature plate and the valve head.

A nice shot down into the injector body. The beveled undercut at the top of the minor o.d. shows very little wear. The swirls at the bottom of the hole are from chips dragging at the end of the twist drill during manufacturing.

And an unmolested version of the poppet image.

This injector had zero clearance with a feeler gauge before teardown. I still need to make a spanner wrench to get the lower assembly apart without damaging anything. This thread has renewed my interest. It's all your fault Rich! I already got too dang many projects on the fire lol.

 

Well... I 'm glad this is back up. I have learned so much since this thread was started. I now look at each picture and can see what the problem was on each pulled injector. "Ah, there's a bad copper washer... and there's a bad middle O-ring seal."

I now know what happened that caused the staining on my original injectors: The lowest O-ring allowed a little fuel by, to rest in the cup. The injector is at an angle, so it sat soaked in the sauce for many seasons. This soaking in fuel at an angle gave it the yellowish stain on the lower end of the body.





Driver Side





Passenger Side