Tappet clatter?

[Wana]

I was out for a drive in the BJ8 on Saturday. The car was running perfectly and the weather was great, sunny and 60 degrees. For some reason I chose to jump off the two-lane and go up the freeway 20 miles back toward home. There was heavy traffic and I was doing about 75 just trying to stay out of everyone's way when all of a sudden the engine started making a loud clattering noise and I noticed a loss of power. I let off the throttle and was preparing to signal off onto the shoulder, when all of a sudden the noise stopped and the engine felt perfectly normal. I got off at the next exit and took a look around and under - nothing leaking, oil level fine. So, I got back in and started it up and drove on home without further incident. Any guesses as to what this was? I've started the car up a few times since then and it ticks over and runs perfectly.

Thanks! Wana

 

[MotorHead67]

Are you sure it was a mechanical (such as metal on metal) noise?
Could the rotor be shorting and the car misfiring?

 

[Wana]

Yes, I am certain it was mechanical and it was coming from the engine as I definitely experienced a power loss while the noise was occuring. It was almost like the engine was "freewheeling" if that makes any sense.

 

[Frank C.]

Wana,
I had a similar thing happen to my BJ8 about two years ago only mine didn't go away. It turns out that a small piece of one of the pistons broke off and ended up attaching to the top of the piston right below one of the valves. Every time the piston was up and the valve was open it would hit the value and make the clatter. When we took the engine out we found that the groove for the top ring on 4 of the 6 pistons was very worn and there were some very small pieces missing.

If this piece hadn't "welded" itself to the piston, it miight have just blown out the manifold. I was lucky and there was no damage to the cylinder but I put in a new set of pistons and rings.

Maybe you had a similar experience.