Injectors or just tips?

[jlawles2]

So the LLY now has 150,000 miles one the original injectors.

Idles normal at operating temperature, but at speed has a diesel knock. Have not checked balance rates as I do not have a way at this time. Could I replace the tips, or do the injectors need to be replaced?

 

[Burn Down]

Most likely a bad tip, but at 150,000 miles I would be looking at replacement & upgrading. You might find the one bad injector & replace it, then lose another in a month or two... Hard to say.

 

[jlawles2]

Just wondering if it is possible that the tips are eroded and causing issues.

If I do injectors, I would do all of them. Not worth doing one only to have another go out next week, and then another, until all of them have been replaced.

 

[rebel7777]

The tips are the most common problem,

 

[othrgrl]

Where are you guys getting this information? I have never heard of swapping tips fixing any problems with injectors, especially when a knock is involved. The ball and seat that most commonly gets worn and prevents complete shut-off of an injector (which causes knock) is not part of the tip, but is in the body. I have heard of people putting on aftermarket tips (which are typically used tips that have been honed) and ending up with the same or even amplified problems that they had before. You need to run a full diagnostic and determine which injector is bad. With how easy the labor is on an LLY I would replace one injector at a time, but not the tip the whole body.

I just sent in a set of LLY injectors with 270,000 miles and only one of them was not able to be balanced and calibrated when I had them taken out to 60% over stock.

 

[Burn Down]

Well I guess we have been set straight. Thanks...

 

[bravo98]

thanks for the info i have a 100k on my LBZ, and am looking into injectors and nozzles. looks like im doing both at the same time.

 

[othrgrl]

thanks for the info i have a 100k on my LBZ, and am looking into injectors and nozzles. looks like im doing both at the same time.

What is wrong with your stock ones to make you want new injectors? For one the LBZ injectors are hard to get your hands on right now so the price is pretty high when you do find them. LBZ injectors very rarely have any issues unless you run very bad fuel through them. If you want bigger injectors you can send your current injectors in, have them tested to ensure they pass all factory test points, then the tips will be oversized and balanced, then re-installed on the bodies and tested, balanced, and calibrated to flow evenly as a set. If you know your injectors are currently in good shape you can skip the initial testing (saving $450) and go straight to the oversizing - then when they test and balance the assemblies at the end they would still catch any problems.

 

[crazycrew]

If you know your injectors are currently in good shape you can skip the initial testing (saving $450) and go straight to the oversizing - then when they test and balance the assemblies at the end they would still catch any problems.

How would one know this? Is this known from balance rates, or some other testing methods?



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[sweetdiesel]

Where are you guys getting this information? I have never heard of swapping tips fixing any problems with injectors, especially when a knock is involved. The ball and seat that most commonly gets worn and prevents complete shut-off of an injector (which causes knock) is not part of the tip, but is in the body. I have heard of people putting on aftermarket tips (which are typically used tips that have been honed) and ending up with the same or even amplified problems that they had before. You need to run a full diagnostic and determine which injector is bad. With how easy the labor is on an LLY I would replace one injector at a time, but not the tip the whole body.

I just sent in a set of LLY injectors with 270,000 miles and only one of them was not able to be balanced and calibrated when I had them taken out to 60% over stock.

I've had 2 bad tips from Kennedy diesel swapped injectors and same issue...
Got new tips and problem solved

 

[othrgrl]

How would one know this? Is this known from balance rates, or some other testing methods?

To be clear for others - on an LB7 I personally would only spend the money to have them enlarged if I knew the history of them and that they were of the latest design. I have kept my eye on too many sets for customers that were fine then suddenly crapped out.

On LLY and newer trucks if we know the history of the injectors we will check everything we can - balance rates, see if it will hold 160 mPa at idle (a way to look for bad return rates), excessive clatter/knock when pressure is turned up, etc. As long as there has never been any indication that the injectors were having problems we will let the customer decide if they want to skip the initial test. After the oversizing process the injectors are completely tested, so they would still find any issues then - but the double work to start with another injector can end up costing more than the initial testing would have.

I've had 2 bad tips from Kennedy diesel swapped injectors and same issue...
Got new tips and problem solved

I am not saying that "aftermarket" tips (typically used stock tips that have been enlarged using one or more of a few methods) can never have issues, in fact I would say the opposite about many of the tips on the market (I have no experience with Kennedy tips/injectors though). This is exactly why I will only buy injectors from and send injectors to the one company that can fully test them assembled to ensure the spray patterns are even, the return rates are in spec, and that they pass 4 Bosch factory test points and have balanced flow at our specified test point. Before I get them in my hands they have been fully tested and I know they are ready to go into the truck and will not give me any problems.