1. SMOKE
The exhaust from underneath your hood should never be excessively smokey. This is a sign of a blown head gasket or a leaking exhaust manifold. These parts and the heat they cause when they are compromised can literally melt other engine parts. You may need a new engine if your vehicle is constantly overheating to the point where smoke is coming out from underneath the hood.
2. KNOCKING
Knocking can happen for a myriad of reasons. If you put the wrong octane in your car the last time you fueled up, this can make your engine knock. This isn’t a reason for an engine replacement, but worn rod bearings can be, especially if they break. When the bearings wear down, the knocking you are hearing is the pistons slamming inside the crankshaft walls. This can seriously damage the engine.
3. EXCESS EXHAUST
You should never see a ton of exhaust flowing out of the tailpipe of your car, truck, or utility vehicle. If you do, you’ve got a fuel, Oil, or coolant problem.
4. METAL SHAVINGS
If you find metal shavings in your oil, you won’t be driving your car for very long. Parts of automotive parts are metal shavings. As oil flows through your engine, worn-down parts release their own metal into the oil. Within hours or days, your engine will seize up and die from this problem.
5. LOSS OF POWER
An automobile may need an engine replacement if it no longer has any pep. With hundreds of thousands of miles on its current engine, it cannot produce the power it used to. Any machine will wear out with age. Engines that are too old and have no more miles on them are considered too old.