How To Spot Water Damage In Used Engines

With the recent flooding that took place in the Houston area, you need to know how to spot water damage in used engines. Here’s where to begin:

How to check for water or flood damage when buying a used engine

  1. Is there flood water in the engine oil? Pull the oil dipstick and inspect the oil.
    1. If the oil stick has water droplets on it, chances are, the engine has been contaminated with water but not run with water in it. If it’s fresh water and the engine has not been run, chances are very good the engine can be saved but it needs to be flushed very soon. If the water has been inside the engine too long the main bearings will start to rust and cause damage.
    2. If the engine oil is milky, that means the engine has been run with water in the crankcase and chances are very good it will have bearing damage or much worse. If the oil stick is dry, remove the oil filter and look at the condition of the oil. If the filter is gone and the engine is drained, remove the oil pan for inspection.
  2. Remove the valve cover and inspect the cylinder head for surface rust
    If flood water has gotten into the engine it will show up with this inspection. When water gets in the engine from flooding it will sit in the oil pan. As the water evaporates, it will rise to the top of the engine and cause surface rust on the bolts, valves and camshaft. If the engine was run with oil in it, there will be signs of milky oil in the oil journals, rocker arms and pushrods.
  3. Look inside the air intake pipe or the throttle body assembly for white residue
    1. If flood water has gotten inside the motor’s air intake you will see places the water has cleaned some residue. When inspecting the throttle body, look for a white residue.
    2. If water appears to have gotten inside this area of the engine it is more than likely ruined. When the engine is run or even attempted to be run with water in the intake it will get pulled into the cylinders. Once water gets into the cylinder, the piston will try to compress it but it can not. That causes a piston to break or a connecting rod to bend. The result is major internal damage.
  4. Visually inspect the area around the spark plugs
    If flood water has gotten up high on the engine the spark plug valley will retain water and corrosion will happen. This is an easy inspection when looking for water damage.
  5. Look closely at wiring harness connectors for a green color at the tips
    When water gets on copper this is a common issue. Also, look at the insulation of the wire harness. When a harness sits in water it will cause the insulation to buckle or look deformed.
  6. Check the color of the power steering pump fluid
    The power steering pump fluid is supposed to be a nice red color. If flood water got inside the power steering pump, the fluid will look very pink.
  7. Check the alternator for corrosion
    The alternator will start to corrode in a short amount of time. Look inside the alternator through the vent ribs, if the copper coil has corrosion you know water has gotten inside.
  8. Check the ac compressor
    The clutch on the front is made of steel and the bearings inside the pulley will make noise if water got inside it.


ASAP Motors finds used engines, motors, and transmissions for sale, then nationwide sellers compete for your business. Just submit a request using our free used engine locator service and our dealers will contact you directly with pricing and information about the Chevy, Ford, Honda, Toyota, or other used motor, engine, or used transmission that you’re looking for.