mtubbs

ok... here's the deal... have a 2003 GMC Sierra 2500hd 4wd 6.0l... just rebuilt the engine... only thing that is the same as before I pulled the engine out of the truck is the block... crank... rods... cam... push rods.. lifters ... intake and throttle body... everything else is new... at least I think I listed everything that wasn't changed...🤷🤦... new pistons and rings... all new bearings... both heads are new... all gaskets and cam sensor.. crank sensor.. coolant temp sensor.. oil sending unit... maf sensor... and the sensor on top front of intake (forget the name of it) are all new.... 1 7/8 tube headers with 3 inch collectors and 2 1/2 exhaust with turndowns at rear of cab... no cats or rear o2 sensors... 1 new injector on account it wasn't supplying number 2 cylinder with fuel... number 2 header tube wasn't getting hot (know because tube wasn't changing color) (stainless headers) and number 7 tube seems to be getting to hot... everything was done to spec per this website and repair/overhaul manual... I put the heavy duty high output alternator off an ambulance on it... 160° thermostat.. new power steering pump and pulley... new water.. oil pump is new... upgraded gaskets... upgraded Accel coils... when I first started the truck, the starter wouldn't kick out... found a loose starter wire... fixed it... fired right up no prob... didn't have exhaust on yet so I couldn't hear the engine... put exhaust on... deleted all codes and kept a p1518 dtc... checked all electric wiring.. spark... compression... went over everything once more before firing up again.. soon as key turns on it went into reduced engine power... turn headlights off while engine is running it would go out of reduced engine power and start knocking... found a bad injector and replaced it and the filter... fired up again after once again checking over everything and clearing dtc.. still knocking but only after about a minute after it's running does it start to knock... maybe a little bit quick...🤷.. but not right as soon as it's started... run a mechanic stethoscope all over everything... EVERYTHING... from front of engine to back of transfer case from top of intake to bottom of pan and the knock can be heard the same EVERYWHERE the same as it could be from anywhere but walking around the engine bay listening by ear and climbing around while it's running knock can be heard from more of the back middle of the engine... but then again from bottom side of 6 or 8 and sometimes from around 7 or 5... like it jumps around... granted the noise quietened down after changing number 2 injector... like the noise db cut in half... tightened up the exhaust... put on the upgraded headers gaskets that I had ordered... cleared out all codes again did an injector balance but no matter what I still have a knock that seems to be coming from nowhere but everywhere... dash reads check oil level but oil level is spot on so I bought an oil level sensor and fixna change it out... can someone please point me in the direction needed to be able to get this thing back on the road before I set the sumbitch ablaze...

mtubbs

number 3 isn't quite as hot as the rest and 7 seems to be way too hot... after changing the injector and doing an injector balance it seems number is trying to come to life and 3 is purring like a kitten but number 7 still seems to be getting a little warmer than the rest but not as bad as it was... and number 2 seems to be cooler than the rest still.. could it have jumped time slightly or what

number 2 cylinder is cold... has spark and compression... that's before I changed the injector

RB04Av

That's REALLY hard to read and figure out what you're asking, or even, just saying. It's kinda like if I tried to write down one of my dreams right after the alarm clock goes off; like a stream of consciousness, as opposed to any kind of narrative or a story with a direction.

Could you use some somewhat less unconventional punctuation, capitalization, spacing, etc. to indicate where one thought ends and the next begins?

SCJW

Could it be a header gasket leak you’re hearing?

mtubbs

2003 lq4 was rebuilt. the only thing that is used from the motor I pulled from the truck is the block, crankshaft, camshaft, connecting rods and lifters. Everything else is new. I put Accel SuperCoil Direct Ignition Coil Set -- Silicone Magnetic Steel Cores; Direct Plug-In Replacement; Square Coil With Vertical Bolt Holes, long tube headers, removed the catalytic converters and rear o2 sensors and ran 2 1/2 inch exhaust. After the rebuild I have an engine knock that starts about 30-45 seconds after startup... can't seem to find where it is coming from. I'm seeking out for any answers that will help me get rid of the knock

mtubbs

new gaskets and are torqued to spec... I have no codes and the oil pressure is 40psi+... coolant temp around 170°... just came back in from messing with it and discovered that when I unplug #5 coil it gets like a double knock sorta sound...

Darth_V8r

iTrader: (4)

Is the knock at engine speed or is it at half speed?

Does it sound like a high pitched tick or a deeper tone?

If you goose the throttle how does it respond? Does it get louder or momentarily disappear?

Initially what you are describing sounds to me like spun-bearing rod knock. Specifically the disabling a specific cylinder improves the sound.

You can get a valve train knock vs a tick. That is usually when a lifter fails and is knocking against the cam lobe. You can usually identify this by pulling the valve cover and finding a very loose rocker.

mtubbs

tblentrprz

Sounds like rocker/valve train. Try to isolate (change in noise) by pulling injector or coil connector to see if you have any other cylinders besides #5 that is concerning. Get a fresh set of ears with stethoscope to isolate location. If valvetrain usually probing at outer valve cover area may help. Ultimately, pull valve covers to check each rocker/lifter setup.

SCJW

Should’ve changed lifters.

mtubbs

it is only #5 that changes when unplugging each coil... I have already unplugged each coil while running and #5 gets a double knock sorta sound

mtubbs

both heads are new, they came completely assembled. the pistons are new... cam, crank, block, rods, lifters and intake are the only thing I reused. everything else is new

mtubbs

it may just be me or whatever.. but it seems like every time I start the truck it changes places... one time it seems like it's from the front next time it'll be back and the middle side... then trans... it just seems to be from anywhere but everywhere each time it's started... idk... about ready to burn the sumbitch

01CamaroSSTx

iTrader: (3)

Should be able to verify before pulling the motor but that sounds like a rod bearing to me.

Che70velle

iTrader: (6)

Long shot here, but sounds like the converter isn’t tight or maybe one of the splash guards around the converter/front of trans is loose...
You can cut the oil filter and see if it’s a bearing really quick and easy. I doubt it with 40 lbs of oil pressure at idle.
If you torch the truck...PLEASE FILM IT AND POST VIDEO HERE...I could use a laugh today.

tblentrprz

OP, that is a pretty heavy knock. 70, may be on to something. Seen it before. You can usually feel a loose converter banging with hand on back of engine. Slide under and make sure converter tight and fire up before putting cover on. That cover can make a pretty good noise too.

It didn't hydro lock and bend a rod did it? (i.e. piston skirt contacting crank CW?)

Pull driver VC and inspect valve train. Is top end getting oil? Crank over and inspect valve train in action. If looks OK, pop on a set of test wires and fire it up and let us know what you see.

FYI - "NEW" means, "Never Even Worked" as far as you know. Been more than one that's been burned by a "new" part that doesn't work as expected.

SCJW

It is pretty loud, but sounds like a lifter to me. Hard to tell in a video. Did it sound like that before the rebuild?

Before you burn it just get in and hold it to the floor and we might find out what it is. 😁

99 2500

Definitely sounds like a lifter noise.

mtubbs

it did not sound like this before... had a blown head gasket and head.. it ran before with no noises only somewhat sluggish...

mtubbs

the heads are reman... and the pistons, oil pump, water pump, power steering pump and alternator are supposedly new... at least I paid for new and not reman