Not every noise is a long block. A tick can be a lifter. Overheating can be a thermostat. The line is when the damage is inside the block or the head has already been through one “maybe it’ll hold.”

Replacement is usually cheaper when you see this

• More than about a quart of oil per 1,000 miles after you have ruled out leaks.
• Metal on the drain plug or in the filter.
• Knock that does not change with octane.
• Coolant in the oil, or oil in the coolant, after a confirmed head-gasket diagnosis that also warped the deck.
• A cracked block, spun bearing, or a rod that already exited the party.

What to do while you wait on a quote

Do not keep driving a knocking engine to “get one more week out of it.” Get the VIN on a quote. Ask the installer to budget timing components, a water pump, and a thermostat while the engine is on the stand. Those parts are cheap insurance.

If the transmission is also tired, say so. Pulling the engine and ignoring a burned 6R80 is how you pay labor twice.