I think I blew it

[Rivup1]

I drive a 1963 Riviera with the 401 nailhead. Love the car. I drove it last weekend and the "hot" light came on at a stop light. I immediately heard a knocking when I moved away from the stop light to pull over. I started it up a week later in the garage and it revs up nice, no problems. I backed it out of the garage, no problems. I slowly accelerated...problems...knocking noise under low acceleration. I pulled it back into the garage, put it in park, slight rev..no noise. Now what ? No leaks, oil is full, coolant is full. Is it a rod ? crankshaft ? I'm calling my mechaninc friend in the morning.

[Airy Cat]

It sounds to me like a rod knock. How many miles are on the engine?
If it has more than 108,000 miles, I'll bet you that it's a rod bearing that has spun on the journal.

[guyopel]

Are you saying you have no eng. knock in rev. ? That would indicate a broken flywheel .
With a rod noise it would be the same in all gears . You can short out the cyls. one at a time to find the one at fault if it's a rod brg.
With the flywheel you can remove the trans. dust cover and sometiimes you can see the broken or cracked flywheel at the center near the crankshaft bolts. I hope it's the flywheel . Good Luck

[Jim Carmichael]

Rods knock all the time not just sometimes. If it got hot enough you may have lost the head gaskets as that is quite common for a Buick. I have changed headgaskets on Buicks that were so hot the rubber boots around the plug wire ends melted and they were fine after new gaskets and a valve grind. When they get hot sometimes a piece of carbon will break loose and it sounds really bad however you can't short it out to make it go away the way you can with a rod knock. It also sounds different so once you know what to listen for you will know what it is.

[Rivup1]

I spoke to my mechanic friend yesterday. He mentioned the flywheel too. He said it could have cracked. It could make sense because I have felt some vibration in the driveshaft area before. Maybe the hot driving condition caused some expansion or load and finally busted it. Well if it's the flywheel I'll feel a lot better. I have a son in college and my wife would like new dining room furniture. Let's hope it's the flywheel.