[TedRamAirII]

Seems if you can put your hand on the oil pan,starter, bell housing, rear cap/oil pan area, etc and FEEL the noise? I would for sure pull the plugs and turn the crank by hand. I think it was Sam from Qatar that showed a video in slow motion, that was great. If you marked the flywheel with a paint mark, and had a timing light on it, in slow motion, you could pinpoint where the noise was in the rotation. That guy in the video with the stethoscope should have found it by now! Good Luck. ; ) How was the oil pump shaft / crankshaft clearance?

[ponchjoe]

Why did Pontiac use the shim behind the flexplate? Aside from flywheel clearance could it be to dampen flexplate noise? Is there any risk of noise from the flexplate being directly in contact with the crank? Is clearance in the bolt holes on the flexplate where it could move back and forth?
Sorry, more questions than answers, just to help exhaust all possibilities .

[Sirrotica]

Not all Pontiacs had the shim, I've put a good many of them together without it and never had any ill effects not using it. Pontiac is the only manufacturer that I have seen use a shim between the flexplate and crank flange, and I have no reasonable explanation of why they used it in some instances, and not in others.

It may have been just a way to take up for manufacturing lateral tolerances, I can't say for certain why it is used in some applications, but not all.

[Va68goat]

I don't know if this will help identify a problem but here are a few pictures of the flexplate after we pulled the motor to address spacing of the windage tray. This flexplate was used on the other motor that was in the car when I bought it. I sent the flexplate to Paul and he balanced it,. When I got the motor and flexplate delivered, I painted the flexplate before we installed it. So after Paul balanced it and I painted the flexplate, I would say I put about 100 miles on the car. As you can see, a spacer was used. I don't know if any of this is helpful...

[Va68goat]

Here are a few pictures of the flexplate after it was balanced and before I painted it

[Sirrotica]

Originally Posted by Va68goat

I don't know if this will help identify a problem but here are a few pictures of the flexplate after we pulled the motor to address spacing of the windage tray. This flexplate was used on the other motor that was in the car when I bought it. I sent the flexplate to Paul and he balanced it,. When I got the motor and flexplate delivered, I painted the flexplate before we installed it. So after Paul balanced it and I painted the flexplate, I would say I put about 100 miles on the car. As you can see, a spacer was used. I don't know if any of this is helpful...

From the pictures it doesn't appear to have cracks in it, although looking at a picture isn't optimum for a diagnosis on this matter. Usually there is rust around the cracks in a flexplate making the cracks stand out, as well as fine metal powder from the 2 edges fretting against each other. The cracks are very obvious in any I have seen, you don't need a magnifying glass to see them by any stretch of the imagination.

Based on the pictures I would say as I earlier posted that it's not a cracked flexplate, but I believe it's in that area of the engine/transmission. Based on the video I watched with the camera/phone moving around under the car while it's running.

For the people that hadn't seen the shim in question between the flexplate and crank flange, it's fairly well illustrated in your first set of pictures.

[Va68goat]

Sirrotica,
Thanks for the reply. Everything that you mentioned is pretty much way over my head but the friends that are helping me that live near me are watching this thread..so that helps. I think we are going to pull the converter back and see if the noise is still present. Since I have a new balanced flexplate, I assume we should just install it huh? I don't know if that's going to help or not but since I have it and its balanced, I assume we just install it. I went back and looked at the dyno video and I didn't hear it either. I don't know if it's because it was pretty loud at the time of dyno though, since I wasn't there. When the motor was installed and running, we heard the knocking sound. After many hours of diagnosis and replacing parts we decided it was best to pull the motor and take a look at the windage tray. We did notice only 1 washer was used to space the windage tray when normally Paul uses two washers. We did notice some witness marks on the windage tray so we added some spacing. I think the noise from the windage tray masked the knocking noise that we hear now.

TedRamAirII,
Unfortunately, I think we have some more testing to do. I certainly wish I knew more about cars to do this myself but I do trust the friends that are helping me. I have no clue about the clearance of the oil pump shaft and the camshaft You had good suggestions..thank you.

ponchjoe,
Hopefully we'll be able to work on the car and we'll take a look at what you mentioned.

[Paul E]

Strip the paint off of the flex plate. It will cause a slight imbalance. Not your noise issue.

[Sirrotica]

Originally Posted by Va68goat

Sirrotica,
Thanks for the reply. Everything that you mentioned is pretty much way over my head but the friends that are helping me that live near me are watching this thread..so that helps. I think we are going to pull the converter back and see if the noise is still present. Since I have a new balanced flexplate, I assume we should just install it huh? I don't know if that's going to help or not but since I have it and its balanced, I assume we just install it. I went back and looked at the dyno video and I didn't hear it either. I don't know if it's because it was pretty loud at the time of dyno though, since I wasn't there. When the motor was installed and running, we heard the knocking sound. After many hours of diagnosis and replacing parts we decided it was best to pull the motor and take a look at the windage tray. We did notice only 1 washer was used to space the windage tray when normally Paul uses two washers. We did notice some witness marks on the windage tray so we added some spacing. I think the noise from the windage tray masked the knocking noise that we hear now.

TedRamAirII,
Unfortunately, I think we have some more testing to do. I certainly wish I knew more about cars to do this myself but I do trust the friends that are helping me. I have no clue about the clearance of the oil pump shaft and the camshaft You had good suggestions..thank you.

ponchjoe,
Hopefully we'll be able to work on the car and we'll take a look at what you mentioned.

As long as you have the new balanced flexplate by all means install it. I really have little faith it's going to cure the noise though. I feel you're in the right area, but if the noise gets cured by changing the flexplate it would be some other issue other than a crack, such as too much run out touching something on the rear side of the engine.

I'm not sure if you've tried a stethoscope, or used a rod to listen for the noise, but it sometimes will point you in the right direction. One other thing I have used to listen to automotive noise is a 1/4 inch piece of vacuum hose placed in your ear, and moving the other end of the hose around to pinpoint a noise. This method is probably better for getting you in the area where the noise is loudest, than listening with a rod or a stethoscope.

Just thought of one more thing, the welded lugs on the torque convertor. I have seen an instance where the lug was fractured. The car was a race car, actually the middle picture in my signature, 67 GTO, so with open exhaust no telling if there was a noise or not. The lug actually finally pulled a section of the torque convertor out, and caused all the ATF to leak out and burn on the hot exhaust system. One of the tack welds on the lugs could have broken off and caused a noise from the movement. Not likely, but this isn't a common noise either.

[TedRamAirII]

According to the Parts Book. All TH400 all V-8 65-75 use a shim Part # 9781615 Group .0666 I was guessing maybe it was a spacer for flex plate distance from crank? but why not just make the flex plate the correct distance to start with? IDK.

[NeighborsComplaint]

2nd post I have seen where the owner painted his flexplate. Why? With an inspection cover in place, you can't see it and the starter gear is going to chew the paint up on the ring gear anyway.

[400 Lemans]

Originally Posted by Va68goat

I don't know if this will help identify a problem but here are a few pictures of the flexplate after we pulled the motor to address spacing of the windage tray. This flexplate was used on the other motor that was in the car when I bought it. I sent the flexplate to Paul and he balanced it,. When I got the motor and flexplate delivered, I painted the flexplate before we installed it. So after Paul balanced it and I painted the flexplate, I would say I put about 100 miles on the car. As you can see, a spacer was used. I don't know if any of this is helpful...

Spacer installs on the outside of flexplate unlike it is in the pictures.

[NeighborsComplaint]

Were there alignment dowels in the trans when you bolted it up to the engine?

[400 Lemans]

Originally Posted by 400 Lemans

Spacer installs on the outside of flexplate unlike it is in the pictures.

Meant to call it a reinforcing ring because its not a spacer.

[Sirrotica]

Originally Posted by 400 Lemans

Meant to call it a reinforcing ring because its not a spacer.

There are 2 parts that I believe are being confused here. There is a reinforcement ring that is sometimes used under the bolt shoulder and on top of the flexplate. There is also a shim that goes between the crank flange under the flexplate.

Either of these parts is not used 100% of the time in all applications. I have no idea of why the factory used them at times and some applications had neither part. Sometimes they had one and not the other.

No matter, IMO these parts are most likely not causing the noise.

[Va68goat]

NeighborsComplaint,
Honestly, I painted the flexplate because I didn't know any better. I'm very new to these old cars and I painted it. I have the inspection cover but it's not on the car. I'm assuming the alignment dowels were lined up. Don't laugh too loud because I am new to these old cars but is it even possible for the dowels to NOT be aligned?

400 Lemans,
I don't know remember if I took that picture the way it was in the car but when we work on the car next weekend, I'll keep an eye out where the reinforcing ring is. Could that cause the knocking sound?

I really do appreciate you guys chiming in and giving opinions and suggestions.

[NeighborsComplaint]

Sometimes the dowels get misplaced and the trans gets installed without the dowels in place, using only the bolts to align the trans input shaft. As the bolts are typically a slip fit, the possibility of misalignment and wear to the convertor and pump can occur.

The dowels are beefy 1/2" steel pins that are pressed into the trans bell housing flange and usually remain there when the trans is separated from the engine. If the dowels are not in place, the minor misalignment could cause the knocking/scuffing you are hearing loading one side of the pump or stator. Elongated convertor mounting holes in the flexplate can have the same effect.

[grivera]

The dowels were in place and aligned with the transmission at time of original install. I was there and bolted the trans to the engine myself.

[NeighborsComplaint]

10/4

[torqhead]

Originally Posted by Sirrotica

There are 2 parts that I believe are being confused here. There is a reinforcement ring that is sometimes used under the bolt shoulder and on top of the flexplate. There is also a shim that goes between the crank flange under the flexplate.

Either of these parts is not used 100% of the time in all applications. I have no idea of why the factory used them at times and some applications had neither part. Sometimes they had one and not the other.

No matter, IMO these parts are most likely not causing the noise.

The shim that you find on some motors between the flexplate and the crank was used when the motor was assembled with the starter and the clearance didn't make build minimum clearance spec (between flexplate and starter) is my understanding.