Skip the auto shop - Our mechanics make house calls

Q: Extremely low oil & knocking noise

asked by on

Out of the blue a knocking noise started coming from the engine so i checked the oil levels and it was completely out of oil, and there is no leak in the system at all so the oil was burned. I was wondering if I could possibly be the PCV valve because of low oil pressure, any other ideas?

My car has 140000 miles.
My car has an automatic transmission.

A: If the engine is to the point of making kno...

If the engine is to the point of making knocking sounds, there is probably internal damage at this point due to the low oil level. If the crankshaft is scored from lack of oil, then oil pressure will not return no matter if the PCV system if good or not.

Your least expensive course is to have a shop or one of our mobile technicians come diagnose the reason behind your low oil level. If the engine is internally damaged, it would not make sense to start replacing parts that may not help your situation.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Buying new tires, have to get same size?

Regarding wider tires, you should be able to go no more than a 225/55-17, but you should make sure by trying one on the rim first.

Q: Wondering about tire swap 2011 Dodge Charger

Hello - yes, the snow tires in the size you mention will work just fine as a swap for your existing tires. Since they are a slightly lower "profile" tire (60 vs 65 aspect ratio), the speedometer will read slightly...

Q: Will it damage my engine if I switch from synthetic blend to regular motor oil to do a oil change being I live in Florida?

It is not snow or ice that will damage an engine but heat and friction. This engine is turbo charged and the turbo bearings are lubricated by the engine oil. When you change the oil you should use only the...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.