Car Talk Newspaper Column: Oil Pump Leak?

The most recent Car Talk newspaper column is about an oil pump that develops an external leak; i.e. leaks oil onto the driveway. I’ve always thought of the entire oil pump as being inside the crankcase area, so if it leaked, the leak wouldn’t be visible. Is it possible for all or most oil pumps to leak oil onto the driveway if a seal fails? Or is it only certain make/model/year/engines that have this configuration?

That was my thought too.

Some GM engines have the oil pump located behind the front engine cover.



Buick V8s and V6s had external oil pumps well into the 80s. They mounted inside the front cover on the passenger side. They could easily leak externally… and be replaced without dropping the oil pan. There were other engines that used similar designs.

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And driven by the distributor drive shaft? Most new engine designs since the 1990’s eliminated the distributor and moved the oil pump to the front of the crankshaft.

This is where the oil pump is located on a 1992 Corolla;



Hmm, did not know that.
Thank you everybody that replied.

Big block Chryslers had part of the oil pump outside the block;

Plenty of YouTubes showing how to replace it.

The vehicle in the Q & A is a 2007 Honda Ridgeline, not an old relic.

The labor involved to replace the oil pump would not make this a practical do-it-yourself project, A/C repairs are easier.

Subarus have an externally mounted oil pump behind the timing belt. The pre-belt Subarus also had an external pump very prone to leaking. What would happen with those is that the O-rings sealing it to the engine block would over time distort from heat.

One or both would take on a 3/4 moon shape and the leaking would begin.

That’s similar to how my Corolla’s water pump attaches. When I recently replaced it both of the old rubber (probably neoprene) o-rings were noticeably distorted and stiff as a board, very much non-pliable. It appeared one of them had actually been leaking, but the other was still continent. The main leak problem tho was the shaft seal, but I can see how those o-rings could become problematic. My truck’s water pump attaches to the block via a normal gasket interface, and while the water pump shaft seal has leaked, the gasket interface has never leaked.

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Chrysler’s 2.5 4 cylinder also had it outside the block, next to the oil filter adapter.

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