I recently picked up a 1968 442 convertible with the original 400. I've already had my fair share of surprises with it, but I guess thats part of the process.

I wanted to get at least the registration of the car all sorted out and the vehicle inspection place was only 3 miles from my house so I figured it would be OK. Car ran great on the 35mph - 45 mph roads. All of a sudden I started hearing a slight knocking sound from the engine compartment. In a panic, I pulled over and by the time I popped the hood (kept the car running) the knocking was gone.

I eventually drove back home. About 400m from my house, the knocking came back. I parked in my garage, popped the hood and the knocking was still there. I needed to take care of things before heading to work so I shut it off. Before leaving, I wanted to crank it back on to get a video of the sound. Engine started up this fine and just sounded awesome again, no knock.

Any suggestions on what this may be? I friend of mine had a similar issue and added a lead additive and the problem went away.

Note: I forgot to mention that I added about 8 gallons of premium gas to my car before the drive. This was the first time for me to fill it up since I received it.

 

A deep sounding knock from within the engine most likely is a worn bearing. Things like this is why it is not practical to take an old car and fix a few things and expect it to be good to go. It will be one failure after another. By the way here is a link to a parts car on NY craigslist, not a conv though. http://newyork.craigslist.org/stn/cto/4385176925.html

 

It didn't really sound that deep when it was going on. It may be a while before I crank it up due to work, but I'll see if I can get a video next time it occurs.

If it is a bearing, would the sound occur 100% of the time when the engine was on? I saw that parts car. I'd like to try to find something as close to Kansas as possible to save on the shipping.

 

You can also check to see if the noise goes away when the knock is heard by pulling one spark plug wire at a time when the engine is running. Often the noise will go away when the offending cylinder is not firing. This will tell if it is a rod bearing or not.

 

From your description, it's impossible to say what was wrong.

Loose converter bolts? Cracked converter? Bad water pump bearing? Bad fan clutch? Loose fan shroud? Loose P/S pump pulley?

The list is long.

- Eric

 

In my experience a bearing if not very bad will not knock all of the time.

 

It may be in the valve train also.

 

Cracked flywheel? Take the belts off the engine, see if the noise is still there. If not, look for loose pulleys, bad water pump, alternator, etc.

 

dose it make noise when driving when it is cold ? and gets worse when hot ??

 

Mine was knocking and it was the power steering pump pulley.


Like everyone says. It could be a lot of things. How's the oil pressure?