LB7: Injectors or Something Else?

[tkempf]

My truck has been running great with no haze at all. Halfway through a 10 mile drive, I noticed a bad lope/knock at idle. Now it's blowing white smoke at idle and a lot of black and white smoke under throttle. I checked the balance rates while in gear and they look terrible (see attached). From what I've read, this sounds like bad injectors. My question is, are lb7 injectors known to fail suddenly like this, or could there be something else causing this?

 

[Burn Down]

What's the age/mileage on these injectors currently? If they are high mileage I would just plan on doing a full set of Bosch remans with the new SAC tips from Lincoln Diesel. If they are low mileage, you can pull all the glow plugs and crank the engine over, see which ones are dumping fuel and go from there. Your balance rates look terrible.

 

[tkempf]

What's the age/mileage on these injectors currently? If they are high mileage I would just plan on doing a full set of Bosch remans with the new SAC tips from Lincoln Diesel. If they are low mileage, you can pull all the glow plugs and crank the engine over, see which ones are dumping fuel and go from there. Your balance rates look terrible.

I've only had the truck for a year so I don't know a lot about its history. I do know all 8 injectors were replaced under warranty in 2008 at 102,000 miles, and I'm assuming that is the set that's in the truck now. The current mileage is 210,000. The problem is I'm in school right now and only working part time, so I've got a very tight budget to work with.

 

[Burn Down]

I've only had the truck for a year so I don't know a lot about its history. I do know all 8 injectors were replaced under warranty in 2008 at 102,000 miles, and I'm assuming that is the set that's in the truck now. The current mileage is 210,000. The problem is I'm in school right now and only working part time, so I've got a very tight budget to work with.

Well, find a beater car to drive... 100k is average for the LB7 injector, even the updated ones. No way would I just do a few with that kind of mileage on them.

 

[tkempf]

Well, find a beater car to drive... 100k is average for the LB7 injector, even the updated ones. No way would I just do a few with that kind of mileage on them.

Yeah, I'm looking at beaters on Craigslist right now. Any chance I could run some cleaner through them and prolong it a few months? I'll graduate in May, so I'm just trying to get by until then.

 

[Whitetail Addict]

I know your pain. The injectors went out of my LB7 in college. Luckily it was under warranty. It's the nature of an LB7.

You can try a healthy dose (quart or so/tank) of TCW-3 2 stroke oil, or GM's injector cleaner. It would be a long shot, but it may buy you some time.

 

[Burn Down]

I doubt cleaner/2 stroke will help but you got nothing to loose.

 

[bigmackmiller]

What did you use to pull those balance rates? Is it an app?, better keep an eye on your oil

 

[tkempf]

I doubt cleaner/2 stroke will help but you got nothing to loose.

Should I worry about doing more damage by running it like this? It knocks and shakes like crazy.

 

[tkempf]

What did you use to pull those balance rates? Is it an app?, better keep an eye on your oil

It's an app called Torque and a cheap Bluetooth scanner from eBay. I checked the oil and it seems fine.

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[Awenta]

I would be looking other places before blaming it all on the injectors. It seems very strange to me that they would just all go out like that.

Unless you got some garbage to go down the rails and kill them. What is your rail pressure like?

Is there any codes?

I'd look at all the wiring too. Also what was said above; pull the glow plugs and crank.

How does the balancer look while the engine is running? Have any blow by?


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[Awenta]

Also what temp are those balance rates taken at?

Doesn't mean much if it wasn't at operating temperature.


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[tkempf]

I would be looking other places before blaming it all on the injectors. It seems very strange to me that they would just all go out like that.

Unless you got some garbage to go down the rails and kill them. What is your rail pressure like?

Is there any codes?

I'd look at all the wiring too. Also what was said above; pull the glow plugs and crank.

How does the balancer look while the engine is running? Have any blow by?


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No codes and no blow by. I haven't been able to read the rail pressure with my scanner, but will definitely have that checked before I tear into it. What should I be looking for with the balancer?

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[tkempf]

Also what temp are those balance rates taken at?

Doesn't mean much if it wasn't at operating temperature.


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That was cold. I was scared to run it for more than a few minutes.

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[Whitetail Addict]

I think Awenta means to watch the harmonic balancer to make sure it's spinning true. If it's wobbling, that can be a sign of a broken crank.

 

[tkempf]

I think Awenta means to watch the harmonic balancer to make sure it's spinning true. If it's wobbling, that can be a sign of a broken crank.

I'll check that. Seems pretty unlikely with a stock (as far as I know) tune though...

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[KyleC4]

Those balance rates are extremely high and very odd that all are like that. I'd definitely be looking at a lot more than just thinking injectors only. Looking at actual vs desired rail pressure is a good start. Also a fuel sample may tell something since it happened all of a sudden. Does truck have an extended crank at all? Did you just recently fill up at fuel station?

 

[tkempf]

Those balance rates are extremely high and very odd that all are like that. I'd definitely be looking at a lot more than just thinking injectors only. Looking at actual vs desired rail pressure is a good start. Also a fuel sample may tell something since it happened all of a sudden. Does truck have an extended crank at all? Did you just recently fill up at fuel station?

Filled up about a week earlier and also changed the filter around the same time. I'll start it up tomorrow and look for some of the things you all mentioned.

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[AllisonTrans Lb7]

Lb7 injectors are known to go bad around 140k I had mine replaced a few years back

 

[07keo02]

I think you have an injector sticking. Maybe #1 cylinder. You need someone with efi live or or tech2 to shut down cylinders one by one to verify. Wouldn't drive it. Broken cranks, and of course a spun balancer, are possible on a stock truck as well.