Thread: Knocking?

Just now i took my grocery getter .....well to get grocerys. When i come out i start it up shift it into reverse and start hearing a knocking sound. It only does it when i shift into a gear and stops if i move and wont start back up again untill i shift it into a gear again. I cant really hear it outside but in car its clear as day. Idk what it could be, valve not opening or shutting? band slipping?

Or on another note could it be from something else? I do know the steering pump i replaced not to long ago is making a grinding sound. Maby when i put it into gear with the rpm change? idk just thinking of all probable causes.

Flexplate?

Originally Posted by Fivefingerdeathpunch

Flexplate?

thinking so ima check tomarrow

Deep knocking, tinny... can you describe the knocking.

Originally Posted by BillBoost37

Deep knocking, tinny... can you describe the knocking.

its not deep but on a side note i have noticed latly its had trouble trying to start
I really havnt had a chance cus of work to take a look at it.
priced the flex though and its $50 my cost from dealer

What usually causes a cracked flexplate on these cars?

Lime green accessories causes broken flex plates



Seriously I'm curious as well seems like some guys have the issue and some don't

Originally Posted by REDCOMPG

Lime green accessories causes broken flex plates



Seriously I'm curious as well seems like some guys have the issue and some don't

General Motors had problems with this on their 3.8L engines several years ago. The bolt pattern and dowel pins may be drilled improperly. When this occurs the vehicle is likely to have continued problems with flexplate breakage. A dial indicator may be used to check symmetrically designed engines. On non-symmetric engines, special jigs and complex measurements may be needed.
The more excessive the misalignment, the more frequent problems occur

Slight misalignment may only cause a single flexplate to break in the life of the vehicle. More severe misalignment can break a flexplate in 15,000 to 30,000 miles. Excessive crankshaft flange run-out or end plate can also cause flexplate cracking. This may occur in worn engines or engine that have been poorly rebuilt. An engine, transmission or torque converter that has been dropped may also have damage that will cause misalignment.
When a running engine ingest water or coolant, the crankshaft may be bent. Liquids will not compress and immense force is placed on the crankshaft and rods. This sometimes happens with a leaking intake manifold or driving on a flooded street. The bent crankshaft will have run-out at the flange and may have continued problems with flexplate cracking.
The same things that cause the flexplate to crack can also cause transmission problems. Damaged and leaking front seals and front transmission pumps are common symptoms.
When a flexplate cracks, it often produces a loud knocking noise as it rotates. The sound is very similar to a bad engine rod and is often misdiagnosed. Removing the bolts to the torque converter and sliding it back into the transmission will often reveal the real problem.
When a flexplate breaks, it is important to find the cause

Simply replacing the flexplate will result in recurrence. Trying to install a heavier duty flexplate will normally pass the problem to the transmission. Correcting the cause of the misalignment is the only repair that will give permanent results.

Welp that was more information then I was expecting but definitely subs to this thread for future references if I do end up having this issue..crossing my fingers.

ugh im praying my allignments are good when i pull this thing out. if not im honestly thinking about demodding replacing it and trading it in. If those dowels are misaligned or who knows maby they are missing lol. We will see......

OMG so tonight i get out of work and i cant hear the knocking so i figured its probly because it was cold and it warming up would cause the flex to expand and cause the knock. So i take a ride to the store and leave it running outside. When i come out and put it into gear i hear it knocking again, so i popped the hood and could hear it clear as day right over the trans. So i just happened to put my hand on the filter and its stops.... rofl. This weekend i took off my intake to clean the maf and when i put it back on apparently i put it like 1/4 inch from the pcm and it was slightly tapping on it when i shifted it into gear. Wow was a relief. Although i did learn quite i few things from this. I swear my car is just doing everything it has just to teach my new things. Atleast this time it wasnt ACTUALLY the flexplate but if it ever happens i know what to look for.

Now to take a shot and drink a beer.

Lmao

I'm laughing...cause... yah I've caused my own headaches before as well. Glad it was such a simple fix.

Lemme tell you about the wheel bearing I swapped out cause I pawed a backing plate and bent it..lol

Originally Posted by BillBoost37

Lemme tell you about the wheel bearing I swapped out cause I pawed a backing plate and bent it..lol

rofl i was kind of excited inaway cus it gave me an excuse to build the trans i had my vacation time all set for 2 weeks from now so i could do it in a span of a week. Oh well Ill be seeing you in about a month Bill, i gotta get this a/f issue worked out

Sounds good.

I have doubts about finding a good mechanic on craigslist. And how can he set the price at $400 when he doesn't even know what's wrong with it?

Originally Posted by apoyer

Hi, I am having the same trouble but I am thinking of taking it to a local guy who is going to charge me $400 to fix it. I am not to sure if I should trust him, I found him on Craigslist. Any comments? Also, I am not very good with cars and I moved so I am trying to look for a good mechanic.

The craigslist guy? yea probly not... What do you meen same issue? Your hearing a knocking? Did the mechanic confirm its a flexplate? What more can you tell us that you know about the issue that could help us in helping you figure out the issue?