Engine noise/knock. What happened?
 

Yesterday I was driving my 1978 with 3.2 ('84). I pulled up from a stop sign and as I got to about 4K RPM in second I heard a loud knock from the engine compartment. At first I thought it was a piece of rock the slammed in the wheel-well but it seemed too loud for that. After this I turned around and drove home carefully.

When I got back I listened for any strange noises and the engine has a low rumbling noise at idle. I did some searching here and found either the alternator or a chain tensioner could cause that rumbling sound but in the different posts about noises I didn't find that anyone had a loud knock before this rumbling starts. I'll do the alternator test (removing the belt etc.) and I'll listen to the chains with a stethoscope when I find one. What I would like to know is if it could be something else and if it is the chain tensioner can I still start the car to do the tests without doing any more damage?

I'm really bummed that I had to leave the car out east and drive back to city in my old Wrangler. It took so much effort to convice my wife that these cars are reliable and make great "weekend" commuter cars.

Thanks
Martijn

I'd pull the plugs and rock the crank back and forth. Take the belt off and rattle the pulley on the ALT.

Re: Engine noise/knock. What happened?
 

They are reliable car when they were brand new twenty years ago, but unless PO's took the efforts and spent the money to maintain them, they are just like any twenty year old cars when it comes to reliability.

Most likely you have no problem. Once you heard the bang you listened closer to your engine than you have before and thereby heard noises that you haven't heard before.

When these things happen to me I drive the car carefully for a few days and decide there is no change to the condition and then go back to driving the crap out of it. You'll hear it if you have a chain tensioner problem. For now don't worry be happy.

-Andy