Oil Leaks. What are the three types?

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Oil Leaks. What are the three types?
The most common oil leak is the one that you can see; also known is a major leak or more to the point the oil that you can see at traffic intersections. This is where an oil leak can become a dangerous road hazard into others, especially motor cycles riding in wet road conditions.
Oil leaks can also be an expensive item to repair so that’s why we see oil patches at major traffic intersections awaiting a potential fatal accident.
A common major oil leak is the rear main seal. This seal is between the engine and transmission. To repair the leak, the engine will require removal, but the problem does not stop there!
If the engine is removed and the rear main seal removed, the crankshaft maybe marked with a slight line exactly where the seal lip is positioned. This slight line on the shaft may allow the rear main seal to continue to leak. The remedy is to either risk another seal and hope for the best or install a speedy sleeve; this will return the shaft to its original surface status. Note not all shafts may have a suitable speedy sleeve available.
Other common major oil leaks are as follows:

  • Oil pressure switch
  • Harmonic balancer seal
  • Camshaft seals
  • Rocker Cover Gaskets
  • Major engine blow by
  • Timing cover

Next is the minor oil leak. This type of oil leak will not show up in your driveway, but will show signs of an oily engine but sometimes difficult to pinpoint where exactly the oil is leaking. To establish where a minor oil leak is starting from, we need to steam clean the engine. Now at this point please read carefully! Never steam clean a hot engine! Why? Because a hot engine will absorb moister within vital electronic components within the engine bay, and this is your worst nightmare! There is nothing worse than getting stuck at the local carwash with a vehicle that won’t start. Only wash an engine if you are confident at doing so, or pass this onto your mechanic. The best time to wash an engine down is when the engine is cold.

Minor Oil leaks are as follows:

  • Head gasket
  • Breather
  • Minor blow by
  • Timing cover gasket

And finally last but not least, the invisible oil leak. This is also the most expensive leak as it sneaks up on you! How does it sneak up? Easy. You check your oil level on a regular basis, then you stop checking it for some reason, but the engine picks up on this and decides to start drinking the oil. Yes, that right, engines drink oil. This is also known as oil consumption, not to be confused with fuel consumption. Oil consumption is where the rings lose the ability to maintain their elasticity, to scape oil back into the sump. So now we need to measure how much oil is added or required between services. Depending on the car is around 1 litre per 1000kms on something like a Subaru. This now becomes a vital weekly or monthly check. The older the car the more regular we need to check the engine oil level.

In my opinion oil consumption is a subject that OEM’S, seem to write their own standard. When an OEM drags out a service interval outside of 10,000kms they may also add on as vital information to the punter or fleet manager, “Check your engine oil level between service intervals”.

By Darren Gow-Brown


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