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Edward, Service Technician
Category: Car
Satisfied Customers: 3153
Experience:  20 + years experience on various makes and models.
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HI guys Can you list a complete set of reasons why a car

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HI guys

Can you list a complete set of reasons why a car engine sump plug falls? The car is a van and has some scratchs in the sump lowest side.

Thanks Customer

Eclayton4 :

Hello, My name is XXXXX XXXXX I will help with your question. Let me first ask, are you speaking of the oil pan drain plug? The plug you remove to drain the engine oil? thanks.



OK, The number 1 reason an oil plug fails is due to over-tightening the plug on oil changes. They only have to be snugged up, but alot of people will over tighten them, and over time it stretches the threads on the plug and then strips them out. Another cause could be impact damage from something on the road. Usually the oil plugs are designed a little softer than the oil pan, So if the plug strips out, a replacement plug is available at most auto-part stores. If the oil pan is damaged, it can be tapped to an oversized plug, or oversized oil plug kits are available. Please let me know if you have anymore questions.
Customer: replied 4 years ago.

OK thanks Eclayton


One of my hipothesis is that, due to the scratchs in the oil pan, a stone impacted the plug (hexagonal head type), produced a tangencial force couterclockwise that unscrew the plug and then with vibration it falls...


Does this make sense for you, according to your experience?

I'll rate immediatly after your next reply.




I see your theory, and its possible but not probable. If the oil plug is on the passenger side of the oil pan, i would say its not possible. As going forward and striking an object would actually spin the plug clockwise. Which would tighten the plug, (unless the object was struck in reverse). Where as if the plug was on the drivers side, striking an object could possibly loosen the plug. So it is possible, but it really would be one in a million for an object to strike the plug hard enough to spin it loose as it usually takes at least 90 degrees of rotation before the plug is finger tight.
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