Industrial Injection Screw-in injector cups

[Delta.Speed]

Hello all,

After a couple of weekends tearing down my new project truck I've discovered what I think is the root of all its current issues. Pretty certain the no.1 injector cup took a crap. See photo below.

After doing some research it looks like this is a common evil on LB7 trucks.

Then I found this Motor Trend article:

Industrial Injection LB7 Duramax Screw-In Injector Cups

If we were to oversimplify how power is made, we’d say this: As more pressure is created in the cylinders, more torque is delivered to the wheels. That pressure

www.motortrend.com

Here's the related product:

2001-2004.5 LB7 Duramax Injector Screw In Cup Kit w/Install Tool And Hardware

The factory injector cups are known for leaking, pitting and seizing themselves to the injectors in your LB7. If you are looking to ensure proper sealing and increased reliability the screw-in style injector cups are a great long-term upgrade for your LB7 cylinder heads Includes: 8 Torque Lock...

www.industrialinjection.com

Now $1,120 for injector cups is a hard pill to swallow..... but I'm considering it for the sake of never having these cup issues again.

What are y'alls thoughts on these?

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[TheBac]

Can cups be damaged removing the injectors, yep.
Can the loctite seal or o-rings fail, yep.
Can they be installed incorrectly, yep.
But they rarely, if ever, fail on their own.

Just went thru this with another person new to LB7s. All he had to do was clean the sealing surface in the heads and reseal the cups.

 

[2004LB7]

unless I'm not seeing what you are trying to show, your photo looks more like the crush washer failed not the cup. either improper torque, reusing the hold down bolts or the hold down bracket bent.

if the cup sealing surface failed, which is what the threaded ones try and prevent, the combustion gases get into coolant and/or coolant gets into the cylinder causing symptoms similar to a blown head gasket

 

[Bdsankey]

unless I'm not seeing what you are trying to show, your photo looks more like the crush washer failed not the cup. either improper torque, reusing the hold down bolts or the hold down bracket bent.

if the cup sealing surface failed, which is what the threaded ones try and prevent, the combustion gases get into coolant and/or coolant gets into the cylinder causing symptoms similar to a blown head gasket

I agree, the injector on the right looks like the copper washer failed and covered the entire body on soot/gasses. If the hold down/hold down bolt is compromised it could cause the cup to lift also but neither the cup/hold down/hold down bolt are pictured.


If the cup leaked it may be visible from lifting but we may never see a bent hold down/stretched hold down bolt with the naked eye as it won't take much to cause the smallest leak.



@Delta.Speed not to say you can't do screw in cups, I just don't think it's worth it for your usage or 99% of people's usage. The only reason I did them is a friend of mine is a machinist and he made a batch of cups so they were extremely cheap.

 

[Chevy1925]

we need to see the sealing surface of the cup and the sealing surface inside the head. I have seen pitted sealing surfaces in the heads causing cup sealing issues. beyond that, if its all cleaned and set correctly, ive never seen the need for the II cups unless you are going for big power.

 

[danzick]

My machine shop ended up doing the thread in cups in my heads. He said cavitation can affect the sealing surface and they don't always seal up after years of use. He said the thread in ones are a lot less likely to have a failed seal. I didnt really want to have to tear it apart again.

 

[2004LB7]

My machine shop ended up doing the thread in cups in my heads. He said cavitation can affect the sealing surface and they don't always seal up after years of use. He said the thread in ones are a lot less likely to have a failed seal. I didnt really want to have to tear it apart

what did the shop do to the cavitated surface? the threads are really only to hold the cups down but if the surface is pitted then the screws aren't going to solve that

 

[danzick]

good question. I didnt ask. Correct me if im wrong. The factory ones rely on a red Loctite type seal between the lower part of the cup and the head? If so, cutting threads into that would eliminate pretty much all of the rough surface? I haven't really studied that system much honestly.

 

[2004LB7]

good question. I didnt ask. Correct me if im wrong. The factory ones rely on a red Loctite type seal between the lower part of the cup and the head? If so, cutting threads into that would eliminate pretty much all of the rough surface? I haven't really studied that system much honestly.

the sealant goes here

vs location of threads

 

[danzick]

ah interesting. IDK than. Maybe the loctite you put on the threads seals the combustion off from that area to help prevent it from reaching the tapered area.

My local machine shop dude has rebuilt hundreds of Duramax engines since 2002, so I wasnt going to argue with him.

 

[2004LB7]

ah interesting. IDK than. Maybe the loctite you put on the threads seals the combustion off from that area to help prevent it from reaching the tapered area.

My local machine shop dude has rebuilt hundreds of Duramax engines since 2002, so I wasnt going to argue with him.

that would be my guess as well. in this photo you can clearly see the pitting. the threaded portion with sealant should take care of any leaking there

 

[Mikey52]

Better mark those some kind of way, or the next mechanic trying to replace a cup, might make a mess trying to get it out.

 

[PureHybrid]

the sealant goes here

vs location of threads
View attachment 107467

I've always put compound on the straight shank too, should be a press fit area

 

[PureHybrid]

Better mark those some kind of way, or the next mechanic trying to replace a cup, might make a mess trying to get it out.

Unless the mech is an oblivious hack, they'll notice what they are

 

[TheBac]

Better mark those some kind of way, or the next mechanic trying to replace a cup, might make a mess trying to get it out.

Very good point.

 

[LBZ]

Unless the mech is an oblivious hack, they'll notice what they are

I’ve never seen a set installed. How does one identify which is in there?

 

[Mikey52]

Installed, if they are not marked differently how would you know? Look at the pictures again.

 

[DAVe3283]

The screw in cups all have some sort of keying on the top so they can be screwed in. That should be pretty obvious to someone who is aware that screw in cups are a thing.

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[2004LB7]

there is a special tool that engages four slots in the top of the cup to tighten them. those slots should be easy to recognize

 

[PureHybrid]

I’ve never seen a set installed. How does one identify which is in there?

These other guys got it covered, but as they said there's notches in the top for the installation tool to engage. Reminds you of an output shaft or axle nut