Found the manifold leak, but....

[bcfishon]

Sounds like you could possibly have a bad piston wrist pin,try removing a spark plug wire, one at a time and see if the noise changes,if and when it does you just found your problem cylinder.

[jabborabbo]

Originally Posted by bcfishon

Sounds like you could possibly have a bad piston wrist pin,try removing a spark plug wire, one at a time and see if the noise changes,if and when it does you just found your problem cylinder.

Ok, when I pull the plug wire off cylinder 3 the knocking stops...wouldn’t a bad wrist pin have a double-click rather than a single knock?

And, the exhaust leak is on the opposite side of cylinder 3....

[bcfishon]

Originally Posted by jabborabbo

Ok, when I pull the plug wire off cylinder 3 the knocking stops...wouldn’t a bad wrist pin have a double-click rather than a single knock?

And, the exhaust leak is on the opposite side of cylinder 3....

Wrist pin sounds similar to a rod or main bearing knock but tends to be noisiest when cold and as motor warms up and expands the noise usually will go away or be less noticable.

[mike16]

Originally Posted by bcfishon

Wrist pin sounds similar to a rod or main bearing knock but tends to be noisiest when cold and as motor warms up and expands the noise usually will go away or be less noticable.

I agree and when you pull a plug and the noise changes from a low frequescy thus to two high frequency clicks, that may also sound like a wrist pin.

Have you ever used a piece of heater hose or old garden hose about 4 feet long, use it like a stethiscope to seek out and localise a funny, (or not so funny) noise,

rod noises or main noises will come from around the bottom of the block. wrist pin noises under load and unloaded are different and can come from lower on the side of the block and up at the top. .lifter noises also come from the side of the block but are more frequent.

descriptions are abstract and subjective. get a a hose and listen to all the different points on several cylinders where moving parts are are doing just that. You will quickly and easily distinguish what parts make what noises, and if one makes a different noise than the other five your heading in the right direction.

your job is easier still because its a streight six rather than a v configuration.