Thread: awkward tapping coming from motor...

Originally Posted by TDCRacing

I have never seen a cracked flex plate but i cant imagibe it sounding like that. I can only imagine it counding like that if it was loose. What about the transmission?Torque converter gone? IDK

I've seen a couple, and they do sound similar to what he posted. All it needs is an inspection.

Though, if he does have a bad one, it would be a fairly bad crack to make that sound.

thanks for the replies and suggestions. dubob, i might take u up on that stethoscope. wanna come by and give me a hand since it sounds like a two man job, one to crank the motor and the other to check the flexplate as it turns? let me know dubob.

also, does anyone have a vid of what a flexplate sounds like? i tried searching youtube but couldnt find anything.

this is oneslogtp's google vid. sounds similiar and if his was a broken flexplate?
broken flexplate? - Google Video


edit-oneslogtp messaged me back and said mine sounds like his and his was a broken flexplate. i'll try to check on it soon, but lack of a 2nd pair of hands kinda suck.

Well all you really need to do is just rotate the crank a little and then check the flexplate. It is made easier with two people as you can have one turn the crank while you look up at the flexplate, but really it can be done by one person as well. It just means you're going to have to inspect closely the flexplate, bolts, look for cracks and such, then roll over and move the crank a little the roll back over and look at the plate again.

If you search for a member by the name of TurboKent and send him a PM, he might be able to offere some insight. He is a local guy that recently dealt with this issue and I think his was due to the flexplate bolts loosening. Super nice guy and if you send him a PM Im sure he would respond back with some info as soon as he could.

Did you hear in that video that as he raised the idle some the noise lessened or went away? Very much like yours.

yes i did watch the clip and it did go away when i revved it on my car as well, but what about when i turned off the car u hear metal clanging around.

Well that could be just the flex plate out of whack. I mean, obviously we cant conclusively rule out other possibilities, but my suspicion is on the flex plate and if it wobbles any at low engine speeds such as idle, then as you turn the engine off and it spins down it stands to reason that the noise would become more prominent. Though the clanging should provide you with some very nice visual evidence that its the flexplate, if indeed it is, when you inspect it as you should see some type of rubbing or scuff marks.

what holds the flexplate cover/shroud? in this vid the guy said theres 3 18mm converter bolts that needs to be taken out?
click here

Okay dont take this the wrong way, but you're making this a bit overly complicated. I understand you are wanting to be fully prepared and know what to expect and look for and you are to be commended for that, few people go through that kind of effort, but we need to take care of first things first

There are three bolts that hold the flex plate to the torque converter, but since you are doing just an inspection at this point, I see no reason to take those out as you want to first check for any obvious signs the flex plate is the truly the issue.

Furthermore, the TC to flexplate bolts are torque to yield bolts, once you take them out, you are necessarily supposed to reuse them. Some say you can, others say why risk it.

But lets take this one step at a time, starting with the simpler things and working to the more complex. The siimplest thing to do right now is to just see if there is any visual evidence that the flexplate is the cause.

Again, Im not meaning to be rude or harsh to offend you, but I think for the sake of getting this isolated for you lets take it one step at a time. If indeed you do not see any visual evidence that the flexplate is cracked or broken then we can move to taking out the TC bolts. I personally would not recommend doing that just yet until you/we know more.

Also, I would NEVER EVER EVER EVER EVER recommend you start that motor and try and shove something behind the flexplate while it was spinning. I about fell out of my chair in shock when I saw that.

none taken, thats why im asking questions on what is best to do first, which in this case is inspect the flexplate for cracks or broken pieces. also i wouldndare start the motor while under the car and jam something in there, its just common sense.

basically crank the motor using the ratchet-technique bit by bit as i inspect the flexplate each revolution correct?

Thats correct. It will be easier to do if you take out the spark plugs, but I realize also thats a lot of extra work to do for just the inspection process. Use a good flashlight or drop light or something like that and if you have one of those inspection mirrors, those little mirrors on a swivel head, that would be perfect as that would allow you to see any cracks and such near the bolt heads.

Originally Posted by SyntheticShield

Thats correct. It will be easier to do if you take out the spark plugs, but I realize also thats a lot of extra work to do for just the inspection process. Use a good flashlight or drop light or something like that and if you have one of those inspection mirrors, those little mirrors on a swivel head, that would be perfect as that would allow you to see any cracks and such near the bolt heads.

unsure what u mean by that, but i'll look for anything that would resemble a crack or something broken

If you don't have a large break bar, can't get to the bolt, can't turn it over, etc, you can try to just bump the engine around. Take a piece of chalk and mark the spot you just checked. Then, bump the engine just a little bit. Check that area and mark with a piece of chalk. And continue on until you have checked the entire way around the flywheel.

'bump' the engine?

Originally Posted by Zef_66

If you don't have a large break bar, can't get to the bolt, can't turn it over, etc, you can try to just bump the engine around. Take a piece of chalk and mark the spot you just checked. Then, bump the engine just a little bit. Check that area and mark with a piece of chalk. And continue on until you have checked the entire way around the flywheel.

Just another FINE piece of information from you Zef.

fst, by bump, he means putting the key in the ignition and just bump it into the start position just enough to rotate the engine a little without actually starting it.

By the 'bolt heads' I mean around where the flexplate is bolted to the Torque converter or to the crank shaft.

good t know thanks guys

*update*
jacked the car up and tok off the plastic dust cover. bumped the motor over a few times and noticed both of the 2 spokes on teh flexplate were cracked as well as what appears to be a small piece/fragment missing on the outer end of one of the spokes. looks like it is a cracked flexplate. although its still bad, im moreso relieved it wasnt the motor, but just the flexplate. right now i have the built tranny on its way t trannyman to tear it down and look into it and see if it needs a refresh, or if need be, an overhaul. hes gonna try to take pics of whathe finds. the gtp's down for the time being as i have another means of transportation so once the tranny comes back to me i can basically kill 2 birds withone stone. replace the cracked flexplate with an l36 one and 2750stall as well as the rebuilt tranny from dave. thats the plan though and often times plans do change unfortunately.

thanks for everyone's help, u guys are awesome!!! i'll keep this thread updated.

Originally Posted by fst

looks like it is a cracked flexplate.

Bet you never thought you'd be so happy to have a cracked flex plate, huh?