Water Pump Seal Leak
A water pump seal leak lets coolant escape from the pump weep hole or gasket area, often leaving crusty coolant residue at the front of the engine.
Can I Drive?
fix-soon
Most Likely Causes
- 1
Worn internal shaft seal
The rotating seal wears and coolant begins leaking from the weep hole.
- 2
Bearing play damaging seal
A loose bearing lets the shaft move and ruins the seal.
- 3
Gasket or mounting surface leak
A failed gasket or corroded sealing surface can leak around the pump body.
- 4
Wrong coolant or corrosion
Corrosion can pit sealing surfaces and attack pump seals.
How to Diagnose It
- 1
Inspect weep hole and pump body
Look for coolant trail, crust, or wetness below the pump snout.
Tool: Flashlight, mirror
- 2
Pressure test cooling system
A pressure test can reveal a pump leak with the engine off and cool.
Tool: Cooling system pressure tester
- 3
Check pulley/bearing play
If the seal leaks with pulley wobble, the pump needs replacement.
Tool: Flashlight
How to Fix It
Replace water pump and gasket
Install the correct pump and gasket, clean sealing surfaces, refill, and bleed.
Repair corroded sealing surface
Address pitting or corrosion so the new pump seals correctly.
Replace belt if contaminated
Coolant-soaked belts can slip or deteriorate.
Mistakes to Avoid
- Do not plug the weep hole. It is a failure indicator.
- Do not keep adding coolant without repairing the leak.
- Do not open a hot cooling system.