Symptoms Of A Cracked Flexplate

[asianANDY 2]

Heard a knocking sound. More like a card on a spoke of a bicycle rim. Next day try to start it, sounded like a weak battery or starter but car started. Did a log, no ST or LT knock(I have a pretty conservative tune). Evic shows 12.1 volts, once I turned the key it goes down to 8 volts then when key is off back to 12.1. I Changed the starter, same issue. Checked inspection plate, no carnage but wasn't able to rotate by hand. Maybe the flexplate or converter bolt is loose and not able to spin freely? Pulled one plug from each cylinder, no damages to the plugs. I tried to start the car again and it struggled, got it to turn over abit but sound like metal was grinding but did not start. I borrowed an inspection camera to check around the flexplate and hopefully will give me better results.

Long story short, will a broken or cracked flexplate cause an engine not to turn over?

[toofart 159]

A dropped bolt will definitely make noise but the noise typically doesn't last long since something breaks. After checking the flexplate I'd pull the valve covers to see if there's damage up top that is preventing the engine from turnung over.

If everything checks out at the back and up top, you could expose the timing set and drop the oil pan to see deeper.

[DevilDogge 25]

Maybe to help rule out something in the flexplate area, I sheared a pin off of somewhere in my clutch assembly and it was rattling around in the bell housing on hard cornering. When I logged it, it pulled timing like crazy thinking it was engine knock, but in reality it was just a little dowel pin banging around. If you logged it while it was making rattling noise, there's a good chance it's not in the flexplate area. .

Here's an idea of what a tiny pin can do.

View from inspection plate

Back of inspection plate.

Bellhousing

Culprit

[asianANDY 2]

Looks like I'll be pulling the heads this weekend. Removed the passenger side valve cover and found this, I hope I didn't do no serious damage. Crossing fingers

[toofart 159]

Figured it would be up top with the no-knock you described. Keep us posted.

[rsbowers 0]

Sounds like you have more than one problem. Obviously the battery isn't causing the noise, but a charged 6 cell battery, as is what is used in automotive applications puts out 1.2V per cell. Meaning a fully charged battery puts out between 12.6-12.7V. A battery that has 12.1V with no load is a discharged battery, this would be the cause of the starting issue. Also a voltage drop of 4V while cranking would indicate a weak battery. After you find the cause of the bent pushrod, I would check all battery connections, and load test the battery. As far as the pushrod goes, could have been as simple as a bad lifter. Hope this helps. Good luck.

[asianANDY 2]

Pulled the passenger rocker off, check to see if there were any broken springs but everything seems to be fine. Pulled the driver side valve covers off and rockers seem tight and no bent pushrods or broken springs. I'll have the battery tested, when it was running it was usually at 13.9-14.1v and 11.9-12ish when it was off. I'm crossing my fingers and hoping it's just bad lifters also. Always heard a bad ticking, sounded like an exhaust leak. I am no mechanic so if you guys got any suggestions or input I'm open to it. The thing that gets me is that I'm not able to turn the motor over by hand which is a bad sign and got me worried.

[Cam 158]

Andy, seriously you can't turn it over?. Is that with a plug removed from every cylinder and if not try that. With plugs pulled you're rotational torque shouldn't exceed 40lbs if you happen to have a torque wrench to check with. The next step is the pull the rockers and push rods and check the rotational value for the short block, that should be under 15lbs and closer to ten. Now if it turns out the bottom end is a good value pull the timing cover and check the timing set and tensioner. I'm almost thinking the tensioner is toast, allowed some slack and you ended up slapping a piston with that bent push rod, problem is there's so much deflection in that rod, it would have really taken a major interference issue to tweek it that much.

[asianANDY 2]

Hey Cam, great info with the rotational torque value. Heading home from work right now and I should be able to mess with the engine for an hour or two. Yes, one plug has been pulled from each cylinder...I'm hoping it's not the tensioner since I just replaced it with a 6.1 less than 5k miles ago.

[asianANDY 2]

Well, 40lbs with the rockers removed and still wouldn't rotate. Pulled the pushrods, removed the manifold. I also checked the cam sensor for any Knicks from the chain being slapped silly, nothing that I can see. Something I haven't done is drain the pan, well do that tomorrow and run a magnet through it.

I appreciate your help Cam.

[Cam 158]

Fuck, that's no good. Pull the cam chain off and rotate the crank and cam. See what ain't spinning. If it's the cam, pull the tensioner plate andsee if it gawled into the cam.

[asianANDY 2]

Piston 1:

Piston 2:

Piston 3:

Piston 4:

Piston 5:

Piston 6:

Piston 7:

Piston 8:

[asianANDY 2]

1,3,5,7:

2,4,6,8:

[asianANDY 2]

[Hemi31 194]

Holy hell who tuned that thing?

[asianANDY 2]

Johan...been running his tunes for 2-3 years now.

[Cam 158]

Under 2,4,6,8 forth picture down, far right. It sure looks like the intake valve has touched a piston. Or did you accidentally do that cause I can't see the corresponding Mark on the piston. Is that cylinder 6 by chance. And have you pulled the timing chain n checked rotation. I forgot one last test for you. If you find its the bottom end that's bound up, remove all the flywheel bolts from the torque converter so you can rule out a converter issue too.

[asianANDY 2]

The picture you are referring to is cylinder 2. Have not pulled the timing chain, you wouldn't believe how long it took to remove the passenger head. The exhaust fought me the whole way, after finding pb blaster exhaust came off in 10 mins. Besides the build up on the surface I don't see any contact on the piston. Coolant on the top of the piston kind of makes it look like they kissed but the pic is misleading. Going to remove the front cover during the week. To remove the flywheel bolts, can I get to the bolts from removing the inspection plate even though it doesn't rotate?

[Cam 158]

Yes thru the inspection plate, but you have to rotate the crank to get to all six bolts.

[Cam 158]



Sorry, can't copy/paste the image on my phone. You have it labeled 2,4,6,8. Under that, the forth pic down of the cylinder head. All the way to the right, bottom of the intake valve looks like a impact Mark. I'll relook tomorrow on a puter and tag it if it still looks that way to me.

Btw, I wouldn't have suggested pulling the heads just yet until you confirmed it's not the cam that's froze up. Please do that before you go any further, it might save you some work.

[asianANDY 2]

If we're looking at the same pic, fourth pic down under 2,4,6,8 is the cylinder 2. I zoomed in the picture see below:

Don't think I can remove the flywheel bolts since I can't rotate the motor. I'll try to get the front cover off asap to see if the cam or crank is not rotating. I sent you a message btw.

[asianANDY 2]

Finally got a chance to work on the car. Removed front cover, Cam spins freely. Tried to spin the crank, I guess it's seized. Wish I knew what exactly happened.

[Cam 158]

Can you remove the verter bolts to flywheel or is it totally froze.

[asianANDY 2]

Totally froze...I can drop the rack, oil pan and check from the bottom but at this point I might as well pull the motor.

[Cam 158]

You're just spinning your wheels pullling the pan. I'm not understanding why you could turn in over with the starter n now now by hand. Obviously it got worse??. You really need to get the verter bolts off to pull the motor. Granted it can be done by not pulling the bolts, but you take a huge chance of bending the input shaft. You told me before the rotating torque was 40lbs, what changed?