You guys ready for a diagnosis? I'm having lots of problems and I don't really know which direction to go in. This is a truck that is only used to tow my boat less than 500 miles/year. I need it to be reliable but I don't need it to be fancy or fast. It's a 77 highboy with a 460 and a C6. Divorced transfer case 4x4.

It has always been hard to start. I thought I had a problem with the starter or ring gear being wrong. I've replaced the starter several times and it works better for a bit and then grinds but eventually will catch and get it started. Let's call the starting problem Symptom A.

Symptom B was a loud metal on metal rattling sound. I first suspected the fan. I removed the fan (and then the alternator belt and power steering belt.) The noise was appearing to come from the back side of the engine. Must be the flex plate or ring gear, right? So I pulled the transmission. The ring gear teeth are half roached but the flex plate seems solid. It appears to be an internally balanced engine (can't see a balance on the harmonic or any weighting on the flex plate.)

Torque converter has a LOT of play when installed in the transmission but since I've never removed a transmission I don't know if this is normal. Check out the video?

The seal in the front of the tranny looks brand new but I have no idea if/when this transmission was ever rebuilt. I'd hate to take it into a shop only to find out the problem is with the motor.

At this point I don't know how to further isolate the noise -- I can't start the engine without reinstalling the transmission. Should I pull spark plugs and turn it over by hand and see if it's smooth or has problems? How do I figure out what the problem is before I just start throwing parts at it?

 

Are you sure the torque converter is fully seated?

 

You are right -- it may not have been seated all the way. I reseated it and updated the video in the original post. It still seems like it has excess play?

 

There should be a little play in the torque converter when its fully seated.

What is the chance the starter is staying engaged? If the starter has worn the teeth around the entire ring gear then I would suspect the starter

 

Yeah, the new video looks more like I would expect.

 

Check to make sure starter is getting full voltage through the cables. It can cause the starter not to fully engage the ring gear.

 

I think the starter may not be fulling engaging the ring gear but the starter is a new PMGR unit and the teeth on it are good. The ring-gear is shot (but only half of the teeth are wiped out -- I think this confirms that the starter is not engaging all of the teeth.)

I don't see a way to mount the starter any deeper, though.

I'll be replacing the flexplate.

Is there a way to check how far the starter is engaging with the transmission out?

This still doesn't address the metal on metal grinding sound that I had when the engine is running. My mechanic friend that listened to it says that it was definitely not the starter dragging. If the torque converter looks good to you guys, what else should I be checking?

Since the transmission is out, I suspect I should change the front seal in it. What else should I be doing maintenance wise before I button it back up?