Truck took a few tries to start, now have knock/tapping noise?

[Capote]

Went to start my truck after it sat a day, turned key and got nothing. Similar to as if you had a low battery. On some tries though it felt like the starter was getting caught up possibly. Well several tries later I heard and felt a loud thud noise and it started, idled roughly with gray smoke. After a minute it was idling normally and there was no gray smoke, but then I heard a knocking or tapping noise coming from underneath the truck. Revved it up while in park and it sounds like a spun a bearing or something i'm guessing. Turned it off and started it back up again and yes the noise is always there now. What the hell happened here? I'm too afraid to drive it and i'm screwed now as this is my only vehicle. I've already had to call out of work.

 

[Mooseman]

And as @MRRSM would say, Jesus wept.... Man, that is certainly bad news. Maybe drain the oil and check for metal. Also open up the oil filter.

 

[Capote]

And as @MRRSM would say, Jesus wept.... Man, that is certainly bad news. Maybe drain the oil and check for metal. Also open up the oil filter.

Yeah this is definetly bad man. I just whooped my ass taking my 100lb jack out to the truck. God that thing kills and me and god am i out of shape. No oil on dipstick tube, but i'm about to drain the oil. I have oil to refill it up with. I do have a spare motor, and I could just use this one as the rebuild turbo motor. The shit part is I have no second vehicle and no way of going to look at one to buy.

 

[littleblazer]

Yeah this is definetly bad man. I just whooped my ass taking my 100lb jack out to the truck. God that thing kills and me and god am i out of shape. No oil on dipstick tube, but i'm about to drain the oil. I have oil to refill it up with. I do have a spare motor, and I could just use this one as the rebuild turbo motor. The shit part is I have no second vehicle and no way of going to look at one to buy.

Well @brianlibby791 brain and I are getting pretty good at pulling engines and stuff if it comes to it.

 

[Mooseman]

Buy a cheap Cruze beater, fix the truck, sell the beater at the same price= free rental

 

[Sparky]

Maybe something wrong with the flex plate, since you said the starter seemed jammed then it went with a thud.

 

[Capote]

Maybe something wrong with the flex plate, since you said the starter seemed jammed then it went with a thud.

That's a possibility, I should of looked today, but this was a messy job and I just took the big ass jack back up to the apartment. Oil was nearly black, smelled burned, and only filled up the 5qt. jug with the used. Which means I was a bit low on the oil too. Got lazy this past year on maintenance and checking the oil level frequently. New rear main seal also leaks a bit still and it looks like my oil filter may of not been fully tightened from when I last did an oil change, bottom of truck is covered in oil.
My big worry now is having to pay for Uber to and from work until I can get the truck to Brandon's to put the other motor in. I also need to buy another vehicle, I can't let this happen again and be stranded at home.

 

[Sparky]

5 quart is def low but I've been 2 quart low before on a vehicle (my truck actually, low oil came up on DIC and it had only 4 quarts in it). It doesn't kill it, it just is not a good idea. As long as you don't lose oil pressure you're still OK on that front.

Wait, didn't you already replace a busted flex plate once?

 

[Capote]

5 quart is def low but I've been 2 quart low before on a vehicle (my truck actually, low oil came up on DIC and it had only 4 quarts in it). It doesn't kill it, it just is not a good idea. As long as you don't lose oil pressure you're still OK on that front.

Wait, didn't you already replace a busted flex plate once?

I've been at 5qts before with the previous rear main seal leakage and aggressive driving. Oh this newer one is leaking just as much, we didn't have a press to properly mate the seal, so Brandon went ahead and used a rubber mallet. Didn't really start leaking until mid-last year though. A year or so after it was actually changed out. No CEL, checked codes to see if anything is hiding, only a rear wheel speed sensor code. Nothing to do with the motor.
Lets say I go under there and see there's an issue with the flexplate, i.e. loose bolt, cracked again due to being misaligned with starter, etc. Could that somehow of caused stress on the crank or something when the starter tried to engage it, if it was stuck??? I'm just trying to think of all possible causes to include my negligence with the oil.

 

[mrrsm]

Mother of God... @Capote...This CANNOT be happening to "The BatBlazer" ...Brother!

I'm with @Sparky on this one... because that "Clunk" sound you describe could have happened if the center of the Flex-Plate 'snapped its moorings' and cracked all around the Crank Bolt Pattern ...and then recovered itself just as the Crankshaft was free for a bit...and then broken out center got grabbed again by the rotation of the Outer Ring Gear when the Starter was actuating. Then after it started up... The Familiar Sound of the "Cracked Flex-Plate ... become a regular tap or knocking noise. I really HOPE this is all it was. If you have to change out the Flex-Plate once again... PLEASE... Change Those Motor Mounts...too!

As for the Leaking Rear Crankshaft Seal... if you intend on Killing the Second Bird with the One Flex-Plate Stone... This time... Polish the FUBARed end of the Crank with some super fine Emory Cloth... just don't go towards the inner race too far...and B4 you begin... pack the back of the Open Block with some Scott Blue Shop Towels to keep the Crocus Cloth Abrasive Rouge Powder from getting inside of the Engine back there. More than likely... when the seal was replaced the last time... it got Nicked up inside on the way in by the old Crank Damage. It never takes much to cause the oil leaks to happen after that because when the crank moves back and forth... it was constantly exposing that rough metal spot to the soft PTFE seal.

 

[Capote]

Mother of God... @Capote...This CANNOT be happening to "The BatBlazer" ...Brother!

I'm with @Sparky on this one... because that "Clunk" sound you describe could have happened if the center of the Flex-Plate 'snapped its moorings' and cracked all around the Crank Bolt Pattern ...and then recovered itself just as the Crankshaft was free for a bit...and then broken out center got grabbed again by the rotation of the Outer Ring Gear when the Starter was actuating. Then after it started up... The Familiar Sound of the "Cracked Flex-Plate ... become a regular tap or knocking noise. I really HOPE this is all it was. If you have to change out the Flex-Plate once again... PLEASE... Change Those Motor Mounts...too!

I'll be checking it out tomorrow or as soon as the weather lets up. You know i'm all too familiar with that all the flexplate craziness, the last one I had broke free around the center and lodged itself stuck again. I still have it, as it's just unbelievable how it was drivable in this condition. I am already looking at ones on Ebay in-case this is the problem. Can't really tell at this point until I get back under. Can only speculate. Either way, be it a motor or flex-plate issue, I've gotta have it towed to Brandon's. No proper place here to swap out a flexplate and if it's the motor, well the spare is in my storage unit in his town. Already started calling my bank about a personal loan, need it for another vehicle and divorce matters anyway.

 

[Mooseman]

Maybe send that oil for analysis? It could tell you what's going on. If it is normal, then the flexplate would be a likely suspect again.

 

[Capote]

Maybe send that oil for analysis? It could tell you what's going on. If it is normal, then the flexplate would be a likely suspect again.

I ordered a kit 3 days ago as a matter of fact because I was nervous if I caused some damage due to my lack of changing it this time. Well not it'll help me get a look at what happened inside perhaps if it turns out to not be the flexplate AGAIN. That'd be easier to deal with than a swap atleast. And it's one less motor swap to do. Don't really care to do it twice on this truck. Already swapped two transmissions out on this guy.

 

[Sparky]

If it IS the flexplate, we'll have to rename the BatBlazer to FlexEater!

But more seriously, if it is the FP, I'd be really curious as to what is making it eat them in the first place. Not like a broken flex plate is the most common thing to start with, then to have it happen twice would be really weird.

 

[Capote]

If it IS the flexplate, we'll have to rename the BatBlazer to FlexEater!

But more seriously, if it is the FP, I'd be really curious as to what is making it eat them in the first place. Not like a broken flex plate is the most common thing to start with, then to have it happen twice would be really weird.

Been thinking of changing the name anyway lol.

Couple of ideas, but it would all stem from that 1st loose bolt that ultimately ended up stressing and cracking my original one. Maybe it screwed with the resonance of everything? Threw rotational balance off and overtime messed with the harmonics overtime while I was driving around with that broken one? I used Loctite on this flexplate and marked everything, guess well see if something is messed up when I get back under there.

I ran some oil of the oil through a paper towel into a coffee cup. I couldn't make out anything metallic looking on the paper towel. When I looked in the cup though I see very tiny tiny shiny particles, some are a brass color. I have no idea if there is normally some metal in oil from an engine with no internal issues. Be it burned oil or good colored oil. I figure there has to be some traces of metal because an engine is naturally going to wear over time, even if it's up-kept.

 

[mrrsm]

@Sparky... as Bizarre as this might seem... I really do believe that THIS Manufacturer's Flex-Plate Warning answers your question... especially if The BatBlazer has never swapped out The Motor and Transmission Mounts:

 

[littleblazer]

@Sparky... as Bizarre as this might seem... I really do believe that THIS Manufacturer's Flex-Plate Warning answers your question... especially if The BatBlazer has never swapped out The Motor and Transmission Mounts:

View attachment 84504

That sheet was in the box for the flex plate I almost used on the 383... I reused all the hardware on the old plate...

 

[Capote]

I re-used old bolts and never swapped my mounts out. The bolts, I probably should of tried to locate new ones, which I never could. I don't see why you'd have to swap your mounts out if they're not collapsed. It's usually pretty obvious when the engine mounts go bad. And I've seen my transmission mount a lot and it looks and feels solid still. That being said I planned on new mounts when I put the second rebuilt motor in. Seems now I may have to use that one as an emergency swap, and use this one as that spare to rebuild if this flexplate looks fine and not the issue here.

*sigh* I have a headache...

 

[Sparky]

Yeah it just says check them and make sure they aren't shot.

There's enough of these rigs out there with worn mounts that haven't busted a flex plate though because the engine and trans are bolted together. Most of that stress should be on those bolts, not the flex plate etc. Shoot if it was up to the rubber mounts to prevent major damage to the flex plate my old car should have had a shattered one a long time before, as the transmission mount was virtually non-existent and one of the engine mounts was torn badly lol.

 

[brianlibby791]

Inspect the flex plate before making a decision. How’s the oil pressure look?

 

[Capote]

Inspect the flex plate before making a decision. How’s the oil pressure look?

Haven't found the oil pressure PID on Dash Command.

 

[littleblazer]

Haven't found the oil pressure PID on Dash Command.

It won't, the sender is still just a switch. You need to hook a manual gauge to the fitting by the filter housing.

 

[Capote]

It won't, the sender is still just a switch. You need to hook a manual gauge to the fitting by the filter housing.

Figured it sent some sort of real reading to the PCM, even though the ones of the cluster are fake.

 

[Capote]

This is the oil after I shook up that 5qt. jug. There's tiny flakes everywhere. Ironically that BlackStone Oil Analysis kit I ordered arrived today. So i'm sending that off to confirm the destruction. Results take a month to get back usually, due to it taking so long to arrive at their location.

 

[Mooseman]

You say you saw "brass coloured" specs. If that is the case, that is death for your bearings as that would be copper. The oil analysis will confirm that or whatever else is going on.

Have you tried starting it again since?

 

[Sparky]

Get that turbo build on!

 

[cornchip]

Has the 4.2 ever had a history hydro locking? Might explain the starter binding up initially.... pooching a rod bearing and seeing a little smoke on start up. Could check for a wet plug.

 

[brianlibby791]

Post a video of it running if you can. Im wondering if the Piston kissed the valve. You really never can know what actually happened until the Engine is torn down. Or maybe a bearing completely lost oil flow and completely f***ed itself.

 

[Capote]

You say you saw "brass coloured" specs. If that is the case, that is death for your bearings as that would be copper. The oil analysis will confirm that or whatever else is going on.

Have you tried starting it again since?

Read that about the copper color I saw last night actually
Started it several times last night, started up like normal. I was comparing the noise to videos I have of when my flex plate was making noise that first time I replaced it after the original cracked, and two other videos I have seen on YouTube of Trailblazer's that also had a cracked flexplate. Sounds similar, haven't found any spun bearing videos that match up to what I'm hearing yet. But with that shit I saw in the oil, guess its not looking good.

Has the 4.2 ever had a history hydro locking? Might explain the starter binding up initially.... pooching a rod bearing and seeing a little smoke on start up. Could check for a wet plug.

Never had a hydro-lock issue before previously.

 

[Capote]

Get that turbo build on!

Not really happy about having to use this motor for that instead of the other one. If it turns out that my flexplate is broken again, something related to this motor is probably lending a hand in that. Don't have a choice really, just glad I have an extra motor. Otherwise the truck would be down even longer and I would never find a good running 4.2 motor for the $500 I payed for Brandon's. Now its just a matter of buying the parts for the rebuild & Turbo portion and another vehicle to get me around in the meantime. His Dad has a truck I used when my TB was down before, little Nissan frontier beater. I asked him to ask his Father if he'd be willing to sell it to me. Would be cheap & reliable.

 

[mrrsm]

The possibility of missing either one or both of the LL8 Engine to Transmission Alignment Dowel Pins could also play a very dramatic role in any repetitions of these Cracked Flex-Plates. In their absence... Even seemingly minuscule misalignments between the back of the Engine Mountings and the Bell Housing can induce Flex Plate Cracking. This article is worth a read to see what the Transmission Experts think about the problem:

http://www.agcoauto.com/content/news/p2_articleid/22

About all those "Floating Particulates" in your 5 Gallon Jug... the Stock GM Main and Con-Rod Bearings in the GM 4.2L Motor are ordinarily made out of Aluminum Silicate... rather than the Tri-Metal style (Copper on Steel with Lead). I have confirmed this first hand on the 2004 LL8 during the complete Tear Down on both the Mains and Connecting Rods... so if there is anything in that Oil of a 'Copper-Bronzey' appearance... the only place it could be coming from would be the Small Ends - Con-Rods - Piston Wrist Pin Bronze Bearings.

 

[Capote]

I have some updates guys

Got the truck up in the air today right after work. Did a little investigating and comparing of the noise to my previous videos of the last time I had a broken flexplate. Pretty close is sound, but just a tad different. Removed the inspection hole cover and the rubber plug from the bellhousing and watched the flexplate and torque converter rotate with the truck running. I didn't immediately notice anything strange, thought I saw a slight wobble in the flexplate, almost unnoticeable. Then I focused on the knocking noise, which was coming right from the bell housing area like right under the torque converter. I put my ear up to it and it was clearly in this area, to be sure I was correct on the location I put my ear as close as I could get to physically touching the rear of the engine block and the noise got farther away.
Turned the truck off and rotated the flexplate, checking all 3 bolts mating the torque converter and flexplate together. Man those babies are tight, couldn't get them to loosen at all (I probably put way too much Loctite, in fear of them loosening again). I also checked for clearance on these bolt heads in relation to the engine block, nothing was making contact. I was sure something had to be amiss though. I rotated the flexplate about 2 more times around and then I noticed something, if I wasn't looking here I would of missed it. I noticed that the lip on the hub portion of the flexplate looked a bit too thick compared to what I remember and going off of pictures I have of it before it was ever installed. The section I looked at looked appeared normal (as in no apparent damage) in width at first , but as I rotated it I started to see what appeared to be a very small separation between the hub and the flexplate. Rotated it even more and I saw a chip and a deep dull looking scratch right in the middle of this small raised lip of the hub. Continued to rotate and the separation I noticed was slightly jagged in appearance. I then noticed that this side of the flexplate became a tad harder to rotate too. I had to be sure my eyes weren't playing tricks, so I once again rotated everything around, paying attention to this raised lip area and it for sure wasn't a consistent depth or look. My suspicion seems to be correct; I believe this flexplate cracked just like the previous one, but in a circular seperation around the hub area without any other cracks spanning off from it. I am attaching photos below, you can see the differences from one side of the hub lip to the next. I won't know 100% until the transmission is removed, but I think i'm on to something here.
First two photos are the same in different lighting to better reveal this blight: (ignore all the oil, replacement rear main seal also leaks......)


Area I started to notice a very minute separation:



As far as the issue with the health of my oil, that's what I get for procrastinating and letting the oil health decrease to the point of internal wear. Lesson learned there, DO NOT PUT IT OFF! If it turns out that a replacement of the flexplate is the only issue, i'll be continuing to baby it after that repair until I can get a second vehicle to take it's place as my daily driver. It'll be getting a refurbished motor for the Turbo atleast. My truck needs a well deserved rest and to officially become just the dedicated project/toy.

 

[Sparky]

Well that would certainly explain the jam and bang when starting.

 

[Capote]

Well that would certainly explain the jam and bang when starting.

It made the truck jerk a bit, I cant imagine how much force it would take for this to happen just starting the truck. Still don't see why it happened. Clearance was good on the bolts, starter was in the correct position.

 

[Mooseman]

There's gotta be something bent or out of alignment to do that on two flexplates.

 

[littleblazer]

There's gotta be something bent or out of alignment to do that on two flexplates.

The right pedal may have something to do with it...

 

[Mooseman]

I drove mine like I stole it and towed a bunch of stuff with torque management turned off. Tranny wound up dying first with 300k km. I've heard of others getting cracked but it's not an epidemic. Just sounds like there is something else at play here.

 

[Capote]

Could be the tune; I have torque management turned off, and shift pressure increased. It bites hard as hell into 2nd when i'm going WOT, makes the tires chirp. Thought it was just belt squeal at first, but turned out not to be. Being lowered a bunch probably has a lot to do with it too. I'm lowered so much that my upper control arms will smash the top of the wheel wells if I hit a bump the wrong way or accidentally hit a pothole. Even my rear axle squished the bump stops a few times. When I do the engine swap, it'll be getting some new engine mounts. Once the Turbo is complete, it won't be a daily driver anyway, so it'll lessen the likely-hood of this occurring again.

 

[littleblazer]

As long as the bell housing is straight it shouldn't affect anything though... the ride height should have no bearing on the drive line unless the drive shaft is smashing into the rear of the trans or something...

I know those bolts shouldn't be that tight... something like 45 ft lbs iirc. I physically cant picture anything causing this unless you have an aftermarket stall and it isn't true.

 

[Capote]

As long as the bell housing is straight it shouldn't affect anything though... the ride height should have no bearing on the drive line unless the drive shaft is smashing into the rear of the trans or something...

I know those bolts shouldn't be that tight... something like 45 ft lbs iirc. I physically cant picture anything causing this unless you have an aftermarket stall and it isn't true.

Probably didn't help I was using a small ratchet with a 2 inch extension. I know I used too much Loctite as well. It'll break loose with a breaker bar and a deep socket I'm sure. Had no room to use mine and I have no deep sockets other than for my wheels.