Rattling sound between engine and trans

[JozefJ]

I have a nasty rattle coming from the area between the engine and the transmission. Already swapped the starter because I thought that was doing it. But the rattle is still there.

Begins at idle, and slightly gets louder while driving and accellerating.

Seems to be coming from the small area Just behind the engine en just before the transmission. Checked it with a stethoscope.

What could be the cause of this rattle and how could I work towards a solution.

Setup iisa 1973 Dart Sport with a 318 and A904

TIA guys!


Can't seem to add a video for the sound, sorry..

 

[Professor Fate]

My first thought is a cracked/broken flexplate, or loose/broken flex plate bolts. Don't drive it, take care of it before it takes out the front pump on the transmission.

 

[4spdragtop]

Yep sure sounds like flex plate.

 

[JozefJ]

My first thought is a cracked/broken flexplate, or loose/broken flex plate bolts. Don't drive it, take care of it before it takes out the front pump on the transmission.

We did check the flexplate through the inspection hatch. All the bolts were intact and tight, and there were no visible cracks in the flexplate.

 

[Kuz]

Check your tranny inspection cover/dust shield, ensure it's tight as well as not hitting anything inside the tranny.

Make sure your exhaust system is tight, including the hangers.

Check the heat-riser on the passenger side manifold.

 

[Lefty71]

All the bolts were intact and tight, and there were no visible cracks in the flexplate.

Not sure of your number of years experience with this particular car.... Did you try removing any of the converter bolts, and check the flexplate for wallowed out holes in the flexplate?? Also (wish I had a pic), if you see an area that looks like rusty dust streaking away from a bolt, it's a bit of a telltale that something might be loose or concealing a crack there.

 

[JozefJ]

Not sure of your number of years experience with this particular car.... Did you try removing any of the converter bolts, and check the flexplate for wallowed out holes in the flexplate?? Also (wish I had a pic), if you see an area that looks like rusty dust streaking away from a bolt, it's a bit of a telltale that something might be loose or concealing a crack there.

My own experience is around 1,5 years of various repairs. Working together with a more experienced crew. We did check the flexplate but didn't take the bolts out. Good idea to explore that next.

 

[toolmanmike]

We did check the flexplate through the inspection hatch. All the bolts were intact and tight, and there were no visible cracks in the flexplate.

It can be cracked at the crank

 

[RustyRatRod]

We did check the flexplate through the inspection hatch. All the bolts were intact and tight, and there were no visible cracks in the flexplate.

Usually they crack around the bolt holes and you cannot always see the cracks. Just keep drivin it. You'll find out what it is.

 

[RustyRatRod]

It can be cracked at the crank

This ^^^^ that's where they normally crack and you cannot see it.

 

[JozefJ]

Usually they crack around the bolt holes and you cannot always see the cracks. Just keep drivin it. You'll find out what it is.

You actually think I could keep driving it? Because I'm well on my way to bringing the car to atumn/winter storage and picking up the work again in spring..

 

[RustyRatRod]

You actually think I could keep driving it? Because I'm well on my way to bringing the car to atumn/winter storage and picking up the work again in spring..

Of course not. I was being facetious. You seem to have a lack of understanding or want to pull it apart. The flex plate is almost certainly 100% what the noise is, yet you seem to not believe it. So keep drivin it. You'll sweep it up off the road waitin for the tow truck. THen you'll know. lol

 

[Professor Fate]

If you're really adamant about not pulling it apart, at least try running it (for a minute or two) after taking off the inspection cover and dust shield.
Very occasionally, if the dust shield is even just a little distorted, the convertor bolts can come into contact with the shield and give you a nasty rattle. In that case, a little straightening and tweaking of the shield should take care of it. Otherwise, I'm afraid you might need to drop the trans to get at that flexplate.
A lot of guys don't even run the shield because some aftermarket bolts have too thick of a head and no amount of finessing completely eliminates the contact.

 

[RustyRatRod]

You actually think I could keep driving it? Because I'm well on my way to bringing the car to atumn/winter storage and picking up the work again in spring..

Here's what you do. Start it up and leave the door open so you can hear under the car and hear the noise. Now, set the parking brake hard and put your foot FIRMLY on the brake pedal. Now, drop it in drive and GENTLY press the gas pedal a SMALL amount, just enough to load the transmission in drive. Notice if the sound changes or even goes away. If it does, pull the transmission and put a new flex plate on it.

 

[1MeanA]

I'll never forget the sound of a loose flexplate after my buddy was rushing me to get things done underneath so we could start the engine.

 

[RustyRatRod]

I'll never forget the sound of a loose flexplate after my buddy was rushing me to get things done underneath so we could start the engine.

The way you put that reminds me of the scene in Heartbreak Ridge where Clint fires the AK at the boys. "It makes a distinctive sound when fired upon" LOL

 

[Ant]

Some good suggestions had already been given, so I'm gonna say there is a little guy with a cow bell inside the converter housing.

 

[Lefty71]

there is a little guy with a cow bell inside the converter housing.

Now why would he want to fix that?? Cant have too much cowbell.

 

[str12-340]

have you removed the dust cover (not just the little bolt cover)? Look at the inside of the dust cover for signs of something contacting the cover. Then run the engine without any lower cover at all and see what you hear.

 

[Bewy]

Is it the gear on the starter coming in contact with the ring gear when under load?

 

[B3422w5]

The way you put that reminds me of the scene in Heartbreak Ridge where Clint fires the AK at the boys. "It makes a distinctive sound when fired upon" LOL

“ This is the preferred weapon of our enemy, it makes a distinctive”…..
Love that movie…. Especially when Swede gets out of the brig and they all think he is going to kick the Gunney’s ***…lol…too funny!

 

[JDMopar]

I've had the same thing going on a few times over the years. Take the positive battery cable loose, jack the car up and take the starter off. Then take the entire dust cover off, not just the little middle inspection plate. Look at the inside of the dust cover for witness marks where the converter bolts have been hitting it. If you find some, straighten the cover. If you don't, leave the dust cover off, put the starter back on and start the car to check if the noise is still there. If the noise is still there, you'll have to remove the transmission and replace the flex plate. It's not expensive, just a lot of work.

 

[furrystump]

Of course not. I was being facetious. You seem to have a lack of understanding or want to pull it apart. The flex plate is almost certainly 100% what the noise is, yet you seem to not believe it. So keep drivin it. You'll sweep it up off the road waitin for the tow truck. THen you'll know. lol

Language barrier maybe, Netherlands. If the bolts are tight and the holes not worn oversized. The 904 has a bit of history of breaking the lugs on the pump drive. I would think that wouldn’t sound like a rattle, but it might. Is this the original setup for the car or did someone install it?

 

[JozefJ]

Language barrier maybe, Netherlands. If the bolts are tight and the holes not worn oversized. The 904 has a bit of history of breaking the lugs on the pump drive. I would think that wouldn’t sound like a rattle, but it might. Is this the original setup for the car or did someone install it?

Fairly late response by me, apologies. It is still the original configuration of the engine and trans. I have replaced the original starter a few weeks ago for a mini starter. How could I find out if the lugs on the pump drive are broken? Could be an interesting item to explore. Will also definately inspect the flexplate en TC. Removing the trans won't be a big issue.

Thanks a lot!

 

[Bewy]

You can spin the lug with a s'driver. Check that both lugs rotate the inner gear. Inspect the nose on the tq c'ter for damage.