I have a 1987 monte carlo and I cant find out what this knocking noise is. I think its something with the exhaust but I dont know. It usually does the sound when im still or hitting the gas. And little suggestion will help.

 

Any way u can post sound/video clip?

 

Usually a knock indicates rod or main bearing....Could also be a wrist pin...(the pin that connects the piston to the rod)..

Doesnt sound like a spark knock....that wont happen at idle....

Does it sound very violent?(Loud)
also does it sound like a single "knock" continuiously as the engine speeds up?
Or more like a rattling "knock" during excelleration? Does the sound stop when you reach a cruiseing speed?

without audio of it..its kinda difficult to diagnosis...

also what motors in it? and how many miles on it?

Or it could be something as simple as a loose heat sheild? on the exhaust...If it sounds kinda "Tinny"...
But I dont believe they used them back then...

 

Well I went to go get checked out, and the mechanic noticed that I was missing the head bolt in the rear of the motor on the passenger side..but it makes a little like knocking sound but very low ever since the put the bolt in.

 

Hmm thats odd:
To be "missing" a headbolt....(maybe someone had it apart) before you got it?
without there being a headgasket leaking....or maybe thats what your hearing? But I dont think it could be mistaken for a "knocking" sound...
I would opt for a compression test...(and leak down test)

Sounds more like a lifter ticking...which will sound off at idle and under power...(accleration)

However, Im leaning towards a bad wrist pin....Is the motor a 305ci?
Was the "knocking" sound on the same side as the missing headbolt?
I dont know how replaceing a headbolt would make it quieter??? without a head gasket leaking...?

Is it running on all 8 cylinders?....

 

The person who had it before had the engine built .The sound was really lound but once they put that missing head bolt in it ticks but not as loud...I dont think its the gasket. I think the motor is a 350 , i really dont know if its running on all cylinders. It really picks up and runs good, its just the ticking.