2000 Bonneville 3800 Series 2

Constant ticking noise that varies with RPM.
Didn't sound as vicious as a Rod Knock took it in Mechanic said it is a rod bearing.
Diagnosed by pulling #6 spark plug and noise disappearing. Not doubting the guy but does this sound legit to you guys.

Rod knock is exactly what it is, a knock. Generally it can be felt throughout the engine. Only way to verify is to drain the oil and drop the pan and check each connecting rod.

Or, it could be lifter tick.

How is your coolant level, oil level, what does your oil look like. What does the underside of your oil fill cap look like???

Oil was good, oil pressure was good, my assumption was lifter tick, I got more info apparently the lifters never stop so removing spark plug #6 would not get rid of lifter tick. Looks like I will be driving her until she dies sucks

If the knock goes away that is a hole with a bad rod.

So its already punched a hole? yay

Taking the spark plug out and running it is noisy and makes it hard to tell what noise is gone or not. It also makes it limp more because there'* no compression in that cylinder.

I do a rough diagnosis on this kind of thing by disconnecting the electrical to the injector on the suspect cylinder while it'* running. Most of the time, if I suspect a rod knock:

1. "knock knock knock"
2. disconnect injector'* electrical connector
3. no more knock, now engine is limping a little and Check Engine light comes on
4. reconnect injector'* electrical connector
5. "knock knock knock"

It'* pretty easy to let an engine idle and go through all cylinders one at a time to figure this out.

Depending on what kind of oil you use already, you might be able to run something thicker to give you more time.

Hole = Cylinder

​​​​​​​Yeah . . . an actual hole punched somewhere would probably stop the engine and make really bad sounds and dump a rainbow of liquids on the ground.

^^^^^ My 97 Bonneville did that years ago. #3 rod punched a whole through the block and hit the starter. I might have pictures somewhere....

So THAT'* what happened to it.