These little rubber rings create a seal. Basically, they squeeze into a groove and fill any gaps between two parts that need to stay sealed against fluids or gases. Think of it like a really reliable gasket, but smaller and usually round. They keep oil, coolant, and other stuff from leaking out, and keep contaminants from getting in. You'll find them all over the engine, but specifically here we’re talking about ones for the crankcase. That’s the lower part of the engine where the crankshaft spins. The O – rings seal things like the oil pan gasket, valve cover gaskets, and various sensors attached to the crankcase. Anywhere fluids or pressure need to be contained, you’ll likely find an O – ring doing the job. Well, without these, you’ll get leaks. Oil leaks are pretty obvious, obviously, but even small coolant leaks can cause overheating problems down the road. These rings are a cheap little part, but a failed one can lead to expensive damage. They act like a shield protecting the rest of your engine. You’ll notice if one goes bad, usually through fluid pooling under the car or a warning light if it affects an important sensor. We carry a good selection of these at Fixparts Online, and it’s always a good idea to replace them whenever you’re doing other work on the crankcase, just as preventative maintenance. They're small, easy to overlook, but super important for keeping everything running smoothly. Long-term solution: O-Ring (MPN 11137804900) comes with a 12-month warranty!

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