Crankshaft seal replacement
Crankshaft seals seal the shaft at its front and rear ends.
Symptoms
- The front seal leaks onto the timing belt.
- The rear seal soaks the clutch, which starts to slip.
What's included
- A front seal leaks onto the timing or auxiliary belt, where oil damages the rubber and may cause breakage. A rear seal contaminates the clutch and makes it slip. Both need repair; the latter requires transmission removal, so combining it with clutch replacement is much more economical. Before replacement, we check crankcase ventilation: excessive pressure forces out even new seals. We install the seal squarely with the correct driver and inspect the shaft’s sealing surface, because a wear groove damages the new part.
Additional checks
- Rear seal replacement is combined with transmission removal
- Installing the seal squarely with the correct driver
- Checking the shaft's sealing surface condition
Why it matters
Oil on the timing belt degrades the rubber and can lead to it snapping, so this leak isn't left unattended. Elevated pressure inside the engine forces out even new seals if crankcase ventilation isn't checked.
More details
The crankshaft seals seal the shaft at the front and rear. The front one leaks onto the timing belt or drive belt — oil ruins the rubber and can cause it to fail; the rear one leaks onto the clutch, causing it to slip. Both cases need attention, and the rear one involves removing the gearbox, so it's noticeably more cost-effective to do it together with a clutch replacement. Before replacement we check the crankcase ventilation: excess pressure inside the engine forces out even new seals. We fit the seal with the correct mandrel, without tilting it, and check the condition of the shaft's sealing surface — wear there ruins a new seal.
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