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Oil leak at the front camshaft seals

The kit supplier for this engine names the front camshaft seals as a common oil leak point and recommends replacing them on a fixed cadence rather than waiting for them to weep — and the reason is not the oil you lose. These seals sit behind the timing covers, which means the oil they leak lands on the timing belt, and a belt that has been soaked in oil is a belt on borrowed time regardless of how new it is. The economics follow from the geometry: the labour to reach the seals is the labour of a timing belt service, so a seal replaced during that job is nearly free and a seal replaced on its own is not. If the front of your engine is wet and the belt history is unknown, read this entry and the timing belt one together — they are the same afternoon of work. This entry rests on one specialist supplier's product documentation, so it is filed at the weakest tier — the reasoning below is sound, but nobody has corroborated it here yet.

Gen 32001–2006Damages other partsAnecdotal

Drive gently — repair soonManeje con cuidado — repare pronto

Anecdotal. This entry is not backed by factory documentation — treat its values and steps as a starting point, not as if they came from the factory manual.

Anecdótico. Esta entrada no se apoya en documentación de fábrica — tome los valores y los pasos como punto de partida, no como si vinieran del manual de fábrica.

Symptoms

  • Oil weeping from the area of the timing covers
  • The oil level falls but nothing pools on the ground
  • A burnt oil smell after a run, strongest with the hood up
  • Black rubber dust in and around the front cover

Likely causes

  1. A front camshaft seal has hardened and is passing oil
  2. The front crankshaft seal has hardened and is passing oil
  3. A valve cover gasket is leaking and the oil is running down the front

Diagnostic steps

  1. Degrease the front of the engine, drive it for a week and look again at where the oil startsPoints toA front camshaft seal has hardened and is passing oil · The front crankshaft seal has hardened and is passing oil · A valve cover gasket is leaking and the oil is running down the front
  2. Work out whether the wet trail begins above the valve covers or behind the timing coverPoints toA valve cover gasket is leaking and the oil is running down the frontRules outThe front crankshaft seal has hardened and is passing oil
  3. With the front cover off, look for black rubber dust and oil on the belt and pulleysPoints toA front camshaft seal has hardened and is passing oil · The front crankshaft seal has hardened and is passing oil

Fix paths

Replace the seals during the timing belt service

$$Difficulty 4/5

Almost all of this cost is access you are already paying for. Doing the seals separately means paying that access twice for a pair of inexpensive parts.

Partsgen3-front-camshaft-sealgen3-front-crankshaft-seal

Replace the valve cover gaskets

$–$$Difficulty 3/5

The cheaper answer when the oil starts above the covers rather than behind them. Confirm the source before ordering, because the two look identical once the oil has run down.

Partsgen3-valve-cover-gasket

Sources

  1. Luso Overland — MONTERO Gen3 OEM Timing Belt Kit: «Front Camshaft Seal - A common oil leak point», with the recommended replacement cadence and the quantity per vehicleVendor cataloguearchived copy