LB7: Injectors, bent rods, or?

[Sledhead]

Hi to all, I've been AWOL for sometime. Blackie has been going down hill the last couple winters. Knocking and fuel smoke that basically clears up after 30 - 60 seconds when it's below freezing, proportional to coldness. Runs great as it has for the last 6 years when warm except a bit stinky of fuel from exhaust.

The balance rates weren't excessive like -3.5 +1 but I understand meaningless on a tuned truck. The injectors are 10 years old with 100,000 so I've been getting another motor ready but it's not yet.

I'm worried it may be short rods and would like to stay "in the club" just a bit longer so I can get my snowmobiles to the cabin before swapping motors. The compression tester is on the bench but the shop is full on motor build and it's fricken cold outside.

With it being so directly related to temp does it indicate rods or could it still be just injectors?

 

[DAVe3283]

It could be injectors, weak/bad glow plugs, or just the tuning. Even a bad IAT or ECT sensor can make it angry.

Unfortunately, the only way to know is to test.

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[Sledhead]

Forgot to mention I did replace 5 bad glow plugs last winter but no change, Fuel heater is questionable and IAH is deleted but it's not really that cold, -10C or +14F

 

[TheBac]

Not saying it is or it isnt, b/c you've got to do a comp test first, but it sounds like the exact same symptoms mine had the winter before I rebuilt.

 

[Chevy1925]

if they are bent, they are just slightly bent and no where near what mine were lol. compression test is the only real answer

 

[Awenta]

Sounds like injectors.

Banana rod will usually give you a balance rate of 15


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[Chevy1925]

Sounds like injectors.

Banana rod will usually give you a balance rate of 15


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unless they just have a slight bend to them. ive seen them go both ways.

 

[WolfLMM]

On healthy injectors, the rod doesnt have to be shortened much to show in the balance rates. You would be surprised

 

[apwcu]

Is the rod bending usually a once and the damage is done sort of thing or is it a slow process that will eventually show up with these symptoms?

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[Dirtymaxx03]

Is the rod bending usually a once and the damage is done sort of thing or is it a slow process that will eventually show up with these symptoms?

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It can bust in half and exit the block or it can bend so slightly that you couldnt tell with the naked eye.

 

[8lug]

Don't mean to hijack but I've got the exact same issue here in AB. I had to cold start it twice now without being plugged in, it didn't used to care, sure does now. Turns over good, starts good, 5 seconds into running starts to shake and buck until it gets warmed up... takes more than 60 seconds for mine though, but it has been closer to -30.

Can injectors do that? And clear up when warm? noticed my mileage went to hell after the first time that happened too... coincidence? Idles good, power is good, boost is good, when warm...

 

[WVRigrat05]

Not sure how the LBZ charging system works, but my LMM alternator comes on slow I guess to be easier on it and the batteries, anyhow it takes it 30 seconds to 1 1/2 minutes and when it starts charging it makes mine idle up and it lopes and shakes for 15-45 seconds. I put the stock tune in and same thing, was told it's the nature of the beast.

 

[Sledhead]

I did a fair amount of reading before posting this thread. I've read balance rates don't mean much without the stock tune and stating fuel rate. Also read that bent rods may not be evident doing a compression test but I plan to have that done in the next couple of days. I'll chase the IAH and fuel heater too.

 

[Sledhead]

The truck died a few weeks ago but it turned out to be a bad filter head. I put a new one on and decided to pull out the dead Airdog that I've been pulling fuel through (plus the stock one) for 6 years. It's been running about the same, still loud and rattly when cold. I did the compression test yesterday all 400 - 420 psi so that's encouraging. Swap a spare CP3 is my next idea, I haven't been kind to it.

 

[Chad006]

You drove for 6 years with a dead lift pump?

 

[Sledhead]

Probably 5. It worked out though, saved me from a bad tank of fuel in the beginning so I wasn't too eager to pull it. I've got a replacement motor from AD but never got to it. That's why I'll try a pump before injectors. I know...

 

[TheBac]

Im amazed it ran decently above moderate throttle with a dead AD. Glad the compression test showed ok. Onto injectors.

 

[danzick]

I'm having the exact same issues with mine. Truck ALWAYS starts in the cold, but rattles and clunks like a pile of junk until it runs for about 20 seconds. It also smokes blue pretty bad for awhile if I turn the high idle on. Its pretty much been this way since I deleted my air intake heater. Ive just dealt with it.