We've been reading about a lot of degas bottles filling with fuel and exhaust soot lately, and about waiting lists to rent injector cup tools. Based on my little experience with this (just my truck), I see only four ways an injector cup can fail.

• Worn/burnt copper washer on the injector tip
• Relaxed injector hold-down bolt torque
• Injector cup seal breaks down
• Temperature cycle stresses on the brass

I don't know about anybody else, but I haven't read anything about the injector cup seal failing, so we're back to issues with the injector washer, bolt torque, or temperature cycling. We can't do anything about the temperature cycling stresses (if that's an issue), but we sure can do something about the injector issues.

I see 200K miles as the magic number where things are getting weird. I offer up the idea that maybe O-rings and washers, plus a good re-torquing are in order at 200K miles as a preventative measure. Of course, many rigs are due for injectors at this time... but maybe not so much if this preventative maintenance is performed. Maybe this could be done at... say... 175K miles. I dunno.

Just a thought tossed out there for discussion.

 

I'm tempted to say mine failed due to the upper cup seal, because I was unable to locate a pinhole or crack in the cups on inspection - certainly not as easy to see as was the one we pulled from Stinky at your place. Mine had very little seal residue to clean away as well, making me think it might have been just adequate until 160K when one or more let loose.

 

I'm inclined to think that failure prevention on the injector cups is a Catch-22. In order to conduct the maintenance required to prevent failure, you must perform actions that can/will eventually lead to their failure. Replacing the crush washers, installing new O-rings, and re-torquing the hold downs all involve removal of the injectors. Or in the case of the last, potentially adding stress to them.

And if this is the case, should injector cup replacement be considered less of a possible repair procedure and more of a scheduled/planned maintenance, albeit conducted at a much longer interval than others? Now, I understand that in the typical lifespan of a 7.3, at most you might replace the injector cups once, if you are lucky. But, could planning for and conducting injector cup replacement before signs/symptoms of failure lead to 600k+ miles, when coupled with other well known longevity maintenance?

I've personally only experienced one cracked cup. That happened while replacing an injector. The cause, could have been coincidental with the torquing of the injector hold down or might have just been a result of age. It was sitting around 200k when it happened.

Another truck I just looked at today for a friend is definitely exhibiting signs of a cracked cup at 253k, after a Ford tech swapped some injectors around.

I'm all for increasing the lifespan of parts. Especially those that require 24-48 hours of down time after replacement. But, its my opinion that anyone planning to conduct performance upgrades should assume that injector cups WILL need to be replaced, not might.

I don't know that I added anything too constructive to the discussion. Just some thoughts.

 

I wonder if the extra power with chip vs. totaly stock makes a difference.

 

It shouldn't, there's a tiny hole between the cylinder and the cup, it's filled with an injector nozzle and a copper washer. Cylinder pressure is the only real difference near a cup.

 

I did my injector seals and washers at 170K(ish) just for preventative maintenance. I was surprised to find two failed lower o-rings on the passenger side front two injectors. Since the fluid had no where to go there was no signs of the failures but I wonder if something like this improves the chances of a failed cup?

 

I changed my seals and cups around 170k because I had a cracked cup, but there was evidence of poor seals on probably 5 cylanders.

 

So what causes the cracked cups we see? Some just wear out a crack from heat cycle stresses at 200k while others run much, much longer with no issues?

I torqued down my injector hold down bolts and ran the stock injectors and stock o-rings over 350,000 miles without any issues. They had over 150,000 miles on them after being torqued down again.

I've got around 435,000 miles on my truck with no replacement of the cups. There's a local guy pushing 600,000 on his with factory cups.

My position is, if one fails, replace them all. If they don't, leave them alone and do your maintenance.

 

That's sure as hell impressive, F350. Question for you, purely for my own curiosity. Had you ever had the injectors out for any reason during that 350k run? I ask because I suspect the repeated removal and installation of injectors is likely one of the leading causes of cracks.

 

Rich, thanks for starting this tread and I think so far everyone who has posted has made some good points. I myself am at 210k on a E99 which have been known to have issues with the injector cup sealant. So I have kicked around the idea of preemptively doing the injector cups and injector orings between 225k -250k. I myself like to fix things before they break or should I say I believe in preventive maintenance.

Now I believe that heat cycling does stress the brass injector cup. And along that line of that thinking I also believe that if you are running tunes and running higher EGT's that wouldn't happen as easily with stock tunes play a roll. Higher EGT's affect the fatigue rate of the brass.

We also have Chris who has 435k on stock injector cups. I think there could be a few reasons for that. First of all I am pretty sure Chris does NOT let his EGT's get out of control. I am also pretty sure he does NOT drive his truck like a punk kid !! I have seen how young guys just beat the living crap out of their trucks. Now also I think the manufacturing of these brass injector cups plays a big part in this too. Well when the dies are new the thickness of the brass cups are more uniformed and as the die wears it creates variations in the thickness of the brass.

Let me ask a question here, why do they use brass any ways for the injector cup? Other than the fact that brass is easy to work with in manufacturing process. Why not make injector cups out of boron steel. Now boron steel is harder to work with in the manufacturing end but in the long run you would have 90% of guys getting 400k-500k out of injector cups if not more.

 

after swithching to an elc coolant in my early bird for nearly 7 months then i started reading about the damage it does to the gaskets and compounds . i was doing the inj and decided to change the cups as well . one was cracked, two slid out with not much pressure (kinda gooey) , and the rest popped out with a loud pop! so it seemed like to me all that i have read was true. just my 2 cents.

 

My thoughts on this:

• High EGTs on a hot tune, malfunctioning engine, or poor driving practices can contribute to an early failure (uneven heat near the tip)
• Short-cycling (many starts and short runs)
• Extreme temps (Alaska vs. Texas)
• Flaws in the brass
• Coolant issues

There are just so many variables.

As for brass vs. steel: If the steel cup goes, we're done... new head time. Brass is difficult enough to pull and install, but steel? It won't compress at the tip. Much (or all) of the sealing is done by compression of the soft brass. Many cups from the factory don't even have a chemical sealant at the top... mine didn't. Even without the sealant, mine didn't leak... it was the crack that did it in.

 

When I bought my E99 with 155,000 miles on the motor. I torqued the bolts when installing new glow plugs. 8 years later and 265,000 miles I have yet to experience an injector failure. My L99 with 199,300 miles I bought last year I haven't yet torqued the injector hold down bolts. Nether truck has a performance chip installed and only a few FTE mods.

Jeff

 

A threaded steel cup on the other hand would have been nice. Because of the different expansion rates of the brass vs the cast heads I would go with simple years of heat cycles causing the cracks over anything else.

Brass cracks quite easily.

 

I am curious of the retorquing the stock sticks on trucks, did you get any amount of turn out of any of the bolts? Were some at spec and some turned a bit?

I am rebuilding an old stove right now and an interesting tid bit. The wire terminals used in ovens/stoves are nickel because any other material expands and contracts to much which eventually loosens up the connection causing a burn out.