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67 coupe with 302/C4 and a 69 Sportsroof with 351w
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Discussion Starter · #1 · (Edited)
This is the 302 in my 67. We thought that it might’ve been a bent flex plate but that’s not it. It seems like the noise is coming from the bottom of the engine towards the rear. The engine has less than 500 miles on it since being rebuilt, but has sat for quite a while. Any ideas?

 

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67 coupe with 302/C4 and a 69 Sportsroof with 351w
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435 Posts
Discussion Starter · #4 ·
Okay, I finally got my boys to upload the video for me.
 

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Could be bottom end but on video at least it doesn’t sound as “tonk, tonk, tonk” as a bad bearing sounds in person. Still might be flexplate related. Did you clean the threads and crank really well and use loctite sealant on them when you torqued the bolts? Did you have the crank secured so that you could get an accurate torque on the bolts?
Another diagnosis step is to pull a spark plug wire(s) and see if the sound changes. When a cylinder doesn’t fire, it doesn’t load the bearing like it normally does and the sound would change up a bit. If that does happen, you’re going back in for either a rod bearing or piston pin issue.
Good luck and keep us posted on what you find,
 

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1968 Mustang Coupe
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Check the torque converter bolts, both head side and thread side, for wear marks. Sounds to me like one or more of those bolts are hitting the separation plate.
 

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I'd get a stethoscope and listen to the oil pan if you think it is coming from that area. I do agree with Barry above, it almost sounds like you have a loose component around the torque converter.
 

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67 coupe with 302/C4 and a 69 Sportsroof with 351w
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Discussion Starter · #8 ·
I spoke to the mechanic this morning and he did say that converter bolts were checked and are tightened to spec.
 

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I agree that something is rattling, and I would think that the converter studs rubbing on the separator plate would be the most likely suspect. To me, the sound seems to be happening at about twice the rate of the engine RPM. This tells me it is unlikely to be part of your rotating assembly, and also supports the idea that more than one of the converter studs is hitting something, maybe a warp in the separator plate or a stamped feature that doesn't agree with the path of the studs.
 

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67 coupe with 302/C4 and a 69 Sportsroof with 351w
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Discussion Starter · #11 ·
I just got back from the mechanic’s shop. He spun the engine over by hand while I pointed a flashlight at the flex plate. When the weight came around, we both noticed some of the gold coating was missing and it looked like it was rubbing. We also noticed some shiny spots on the torque converter bolts showing they were rubbing as well. I noticed that the separator plate was flush with the starter at the bottom, but as you went up there was a gap of 1/8 inch or more. Now we’re thinking of how to fix the warped separator plate.
 

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I just got back from the mechanic’s shop. He spun the engine over by hand while I pointed a flashlight at the flex plate. When the weight came around, we both noticed some of the gold coating was missing and it looked like it was rubbing. We also noticed some shiny spots on the torque converter bolts showing they were rubbing as well. I noticed that the separator plate was flush with the starter at the bottom, but as you went up there was a gap of 1/8 inch or more. Now we’re thinking of how to fix the warped separator plate.
They're relatively inexpensive. Buy a new one.
 

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I just got back from the mechanic’s shop. He spun the engine over by hand while I pointed a flashlight at the flex plate. When the weight came around, we both noticed some of the gold coating was missing and it looked like it was rubbing. We also noticed some shiny spots on the torque converter bolts showing they were rubbing as well. I noticed that the separator plate was flush with the starter at the bottom, but as you went up there was a gap of 1/8 inch or more. Now we’re thinking of how to fix the warped separator plate.
Yeah, just get another, as Bart said. I have found that the holes for the dowels are very tight and slightly misaligned on some of these in the past. I've had to use a die grinder to make them fit without some tension. I'm wondering if that's what made the issue for you. If the holes weren't perfect and then you tightened everything, it would probably cause the thing to bow out in the middle somewhere. Make sure it goes on without having to force it over the dowels and that the bolt holes are on center before you install it again. Another example of a replacement part that we have to "make fit".
 
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