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On many engines the oil pump sits on the front of the crankshaft, and its seal is the front crankshaft seal. When that seal hardens or wears a groove, oil leaks out behind the crank pulley. Route 66 Auto Repair in Upland replaces oil pump seals, checks the surface they ride on, and protects the timing belt, which oil will ruin, on engines that have one.
Signs of a leaking oil pump seal
- Oil flung in a ring pattern around the crank pulley area
- Oil on the timing cover and the front of the pan
- A burning smell as oil reaches exhaust parts on sideways-mounted engines
- An oil-soaked accessory belt
- Front-of-engine drips that return quickly after cleaning
Why does this seal matter on timing belt engines?
A rubber timing belt soaked in oil swells and loses grip. It can skip a tooth or fail early, and on many engines that means valves striking pistons. If your engine has a timing belt and the pump seal is leaking onto it, the belt should be replaced along with the seal, not left in place.
It works the other way too. When a timing belt is due, the pump seal, camshaft seals and often the water pump are replaced in the same visit because they are already exposed. The written estimate lists each as its own line. Seals on the back side of the pump are covered on oil pump gasket repair.
What do we check on the crankshaft?
A lip seal rides on a polished band of the crankshaft or the pulley hub. Years of use can wear a groove there, and a new seal on a grooved surface leaks again soon. We inspect that band, and where a groove is found, we use a repair sleeve or set the new seal slightly off the old track, as the design allows.
How we replace an oil pump seal
Step 1: Confirm the source
We clean the front of the engine and confirm the leak is at the pump seal, not the timing or valve cover.
Step 2: Remove pulley and covers
The belt, crank pulley and any covers in the way come off.
Step 3: Inspect the surface
The seal track on the crank or hub is checked for grooves.
Step 4: Install the new seal
The seal is driven in square with the proper tool, its lip lubricated.
Step 5: Reassemble and verify
The pulley bolt is torqued to spec, the engine runs, and we check the front for weeping.
What's included in pump seal replacement
Included on the work order
- 01Leak source confirmation
- 02New oil pump or front crankshaft seal
- 03Seal track inspection
- 04Repair sleeve where needed and approved
- 05Crank pulley bolt torqued to spec
- 06Post-repair leak check
When is a pump seal leak urgent?
Need now: call
- Oil reaching the timing belt
- Oil dripping on the exhaust or the accessory belt
Need later: book
- A light film on the timing cover of a chain-driven engine
- A seal due for renewal at the next timing belt service
What drives the cost?
The seal itself is inexpensive; the labor to reach it depends on whether a timing belt, chain cover or engine mount is in the way. If the seal sits behind a timing belt that is due or oil-soaked, the estimate includes that option so you decide once. AAA members get 10% off parts and labor, up to $75, with the card at the time of service. For leaks elsewhere on the engine, see engine oil leak repair. Pump output problems are covered under oil pump repair.
Frequently asked questions
Is the oil pump seal the same as the front main seal?
On many engines, yes. The front crankshaft seal sits in the oil pump body or the timing cover. Either way, it seals the crank where it leaves the front of the engine.
Can I wait until my timing belt is due?
If the leak is light and nowhere near the belt, often yes. If oil is reaching the belt, no. We show you where the oil is going before you choose.
Does a leaking pump seal lower oil pressure?
Usually not, because it is an outside leak. Pressure only drops if the oil level falls far enough, so keep an eye on the dipstick until it is fixed. Top it off with the grade in your manual.