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Texasdude74 · 11-30-2016, **(Subject: Injector Life Expectancy )**

Some people get a million plus out of injectors and some seem to need new ones every 2-300k. How you run the truck makes a huge difference.

I personally consider non Detroit injectors worn out between 20-25k hours and 5-6k hours for a Detroit. I also would never rebuild an engine and not replace all six injectors, no matter what brand of engine. Weak injectors take a heavy toll on an engine. It's not anywhere near as simple as they either work or they don't with diesel injectors. They can do all kinds of screwy things and fail in different ways.

Rig Wrench · 12-01-2016, **(Subject: Injector Life Expectancy )**

I've done all 6 in 100k on my 871. I have a theory that at the power level it's at the extended duration is taking its toll. I back up this claim with absolutely nothing, just all that makes since. Started getting a lot of rumputy rump on start up. Checked for bubbles, had on 3 front cylinders. shortly after systems arose again, back 3 replaced and problem solved. Only has just over 100k miles still, total

Texasdude74 · 12-01-2016, **(Subject: Injector Life Expectancy )**

(12-01-2016 )Rig Wrench Wrote: I've done all 6 in 100k on my 871. I have a theory that at the power level it's at the extended duration is taking its toll. I back up this claim with absolutely nothing, just all that makes since. Started getting a lot of rumputy rump on start up. Checked for bubbles, had on 3 front cylinders. shortly after systems arose again, back 3 replaced and problem solved. Only has just over 100k miles still, total

This is probably a testament to the current state of remanufactured injectors more than anything else. I believe there's a big advantage in running your business on an engine platform where you can still get ahold of brand new injectors. Versus having to make due with reman stuff, they just don't last. More importantly, the sellers of this crap don't stand by their junk or the secondary damage it so often causes: washed out cylinders, hammered rod bearings etc.

Hammerhead · 12-01-2016, **(Subject: Injector Life Expectancy )**

(12-01-2016 )Rig Wrench Wrote: I've done all 6 in 100k on my 871. I have a theory that at the power level it's at the extended duration is taking its toll. I back up this claim with absolutely nothing, just all that makes since. Started getting a lot of rumputy rump on start up. Checked for bubbles, had on 3 front cylinders. shortly after systems arose again, back 3 replaced and problem solved. Only has just over 100k miles still, total

Help me understand your thought process...

The injectors are cam driven on an 871. (To me) That means that the injector travels 100% top to bottom every second rotation of the crankshaft. There are no electronics on the actual injector, the timing and metering are done externally. The only difference on the injector cycle is the amount of fuel volume in the metered & timing portion of the injector to control timing & injected volume. If I am understanding this correctly, then the engine work load plays zero effect on the number of cycles that the injector should theoretically last.
Yes I understand work/torque load equals heat, and heat shortens the life expectancy of intricate working components like injectors...but besides that, should all else not be equal?
If not, then what am I missing?

Rawze · 12-01-2016, **(Subject: Injector Life Expectancy )**

(12-01-2016 )Hammerhead Wrote:
(12-01-2016 )Rig Wrench Wrote: I've done all 6 in 100k on my 871. I have a theory that at the power level it's at the extended duration is taking its toll. I back up this claim with absolutely nothing, just all that makes since. Started getting a lot of rumputy rump on start up. Checked for bubbles, had on 3 front cylinders. shortly after systems arose again, back 3 replaced and problem solved. Only has just over 100k miles still, total

Help me understand your thought process...

The injectors are cam driven on an 871. (To me) That means that the injector travels 100% top to bottom every second rotation of the crankshaft. There are no electronics on the actual injector, the timing and metering are done externally. The only difference on the injector cycle is the amount of fuel volume in the metered & timing portion of the injector to control timing & injected volume. If I am understanding this correctly, then the engine work load plays zero effect on the number of cycles that the injector should theoretically last.
Yes I understand work/torque load equals heat, and heat shortens the life expectancy of intricate working components like injectors...but besides that, should all else not be equal?
If not, then what am I missing?

Your missing the heat factor. I have seen a many of clogged DPF can and/or exhaust restrictions, overspooling turbo's from bad deletes or bad sensors, etc. kill injectors on CM871's. Symptoms of cooked injectors,.. rough idle, and quite leaky when tested.

If you do an injector leak test, and one or more is barely leaky,.. and very hard to find when wrenching the engine,.. it is not likely to cause any problems or fuel mileage issues,.. but if you can find it fairly easily by wrenching the engine,.. it is definitely bad.

I typically will not tell someone to replace a $600+ injector unless it can be confirmed it is bad without question, or they are very old (more than 6000+k and you are having significant rough idle and/or engine issues already. I have seen a lot of trucks with slightly leaky injectors (can't find them when wrenching the engine but leak a tiny bit when cranking) that don't have idle issues with really good fuel mileage and not have any issues with them whatsoever.

Brock · 12-02-2016, **(Subject: Injector Life Expectancy )**

(11-29-2016 )Unilevers Wrote: they would also NEVER get back in after a inframe. but to me a inframe is alot more than pistons and liners.

While I'm sure we all agree..... Sometimes the wallet and me have a difference of opinions! :s

DUKE58 · 12-02-2016, **(Subject: Injector Life Expectancy )**

after my inframe on paper I am getting 10.5 mpg.But I never have over 6000 lbs in trailer

in2trux · 12-02-2016, **(Subject: Injector Life Expectancy )**

(12-01-2016 )Hammerhead Wrote:
(12-01-2016 )Rig Wrench Wrote: I've done all 6 in 100k on my 871. I have a theory that at the power level it's at the extended duration is taking its toll. I back up this claim with absolutely nothing, just all that makes since. Started getting a lot of rumputy rump on start up. Checked for bubbles, had on 3 front cylinders. shortly after systems arose again, back 3 replaced and problem solved. Only has just over 100k miles still, total

Help me understand your thought process...

The injectors are cam driven on an 871. (To me) That means that the injector travels 100% top to bottom every second rotation of the crankshaft. There are no electronics on the actual injector, the timing and metering are done externally. The only difference on the injector cycle is the amount of fuel volume in the metered & timing portion of the injector to control timing & injected volume. If I am understanding this correctly, then the engine work load plays zero effect on the number of cycles that the injector should theoretically last.
Yes I understand work/torque load equals heat, and heat shortens the life expectancy of intricate working components like injectors...but besides that, should all else not be equal?
If not, then what am I missing?

What you are missing is the fatigue factor over time to the spring and lag from contamination to the check valves and passages. Add to that cascading effect of wear of timing and metering actuators, flow restrictions from wax build up of contaminates in very fine orifices.
Unless everything is near perfect there is a cumulative effect to the mechanical system.
I assume there is a big difference between new and less stringent reman standards that throw a wrench into the works.

https://youtu.be/_WeiDC6S8Lw

Hammerhead · 12-03-2016, **(Subject: Injector Life Expectancy )**

(12-02-2016 )in2trux Wrote: What you are missing is the fatigue factor over time to the spring and lag from contamination to the check valves and passages. Add to that cascading effect of wear of timing and metering actuators, flow restrictions from wax build up of contaminates in very fine orifices.
Unless everything is near perfect there is a cumulative effect to the mechanical system.
I assume there is a big difference between new and less stringent reman standards that throw a wrench into the works.

https://youtu.be/_WeiDC6S8Lw

I understand the spring fatigue and erosion/abrasion wear in the nozzles and check valves.
I know that carbon deposit buildup on the injector tip face interferes with proper spray patterns as well. Thanks for the link, I have watched all of Daniel Babbit's videos years ago in attempts to better understand these engines.

My question was directed to Rig Wrench where he stated...

(12-01-2016 )Rig Wrench Wrote: I've done all 6 in 100k on my 871. I have a theory that at the power level it's at the extended duration is taking its toll. I back up this claim with absolutely nothing, just all that makes since.(sic)

I'm having a hard time wrapping my head around "power level and its associated extended duration" taking enough of a toll in 100k miles to warrant changing them.
I don't know what kind of power levels he is at or his torque load demand, or anything else for that matter, but as someone who uses above average torque load due to my type of work, I'm trying to understand where he is coming from to see if there are any correlations I can draw to my application that may help me prevent an unforeseen premature failure.