acermcgraw

Hi there all, i just posted about removing my transmission because i was sure i had a cracked flexplate or at least a loose one, based on posts i have read on these forums.

The only issue it that when i finally got time to check today i was surprised to see a very nice looking flexplate with no abnormal wear and certainly no sort of cracks. I am baffled to say the least, i know what ard knock sounds like and this is deffinatly not a rod knock. it really sounds like it is coming right from my bellhousing area.

My only regret is that i did not put a wrench on the bolts of the flexplate to see if they would turn. I didnt beqcasue when i grabbed the flexplate and pulled and pushed it and banged on it with my hand it didnt budge..

so my question if for anyone who has had confimed loose bolts on their flexplates. Did the plate itself seem loose or did it seem tight untill you put a wrench on it? any help would be greatly appriciated. thanks.

BlueXJ

Mine was tight but had hairline cracks that I almost missed when I pulled the motor. I was gonna replce the motor b/c I thought it was knocking. When I pulled the motor and was getting ready to pull the flexplate to put on the other(new) motor my buddy stopped me and made me look closer and there were I think 4 hairline cracks and so we went and got another flexplate from a dealer and installed it. Put the original motor back in and the knock was gone. I would have never thought those hairline cracks would have made that type of sound but I don't have another explanation.
BTW Jeep is still runnin' strong on the same motor and that was in 2005. My daughter is still drivin' the crap out of it.

acermcgraw

Where were the cracks located on the flexplate?

BlueXJ

Between the holes on one side and a short one between two crank bolts.

okcjeeper

Also that sound could be caused by a bad harmonic balancer...sounds odd but seen it happen...So might be worth a look.

BlueXJ

Yeah I've seen that reported too. Never had it happen to mine but it is supposed to sound similar to a knock.

whowey

Makes a heck of knock.. Almost sounds like something trying to pound a hole through the oil pan.

acermcgraw

oh ok , how would i really diagnose that without just replacing it. And the harmonic balancer is the same thing it is on all cars right? the wheel on the end of the crankshaft right? (front of engine) i know that sounds dumb but im just making sure there isnt something else that i dont know about. The sound is accompanied by a substantial and slow vibration.

If it is the harmonic balancer, would i need a gear puller to get that thing off?

It does really sound like the sound is coming from the bellhousing but i could be wrong.

whowey

Mine you could see the problem with the balancer. The rubber piece in the middle had come out of it. I needed a 2 jaw puller to get mine out.

acermcgraw

there is a rubber piece? you wouldnt know of any pics of that online or anything?

acermcgraw

hey guys I just looked at my harmonic balancer and it looks like it has some sort of rubber ring that has half fallen out and torn is this an issue?do u think this could cause the tapping and or vibration?

whowey

Maybe.......

acermcgraw

thanks, i did see all of those quotes before,they are actually the very reason i posted my last question, i am trying to find out if just half of the rubber grommet being gone would make a difference because the last gentleman said his was all the way gone. Thanks.

BlueXJ

Yes that throws the harmonic balancer out of balance thus it vibrates and slaps around. That slapping is transfered through to the flywhhel and everything in between. That is why it sounds like knocking.

Olivegreenxj

if the balancer is in very poor shape it can actually do damage to other pulley bearings and components!, I have just replaced a power steering pump bracket on a 92 cherokee that was cracked/broken beyond repair because the balancer was so out of shape it was pulling on the belt and flexing the bracket, eventually it cracked and broke, a very simple component can cause a very serious complaint!