Soft knocking sound, goes through a lot of oil but I don’t ever see it "leaking" from anywhere.

Soft knocking sound, goes through a lot of oil but I don't ever see it "leaking" from anywhere. No puddles left at my parking spot at home or work. Lady from work said I had huge white smoke coming out of my tailpipe when driving home from work. Knocking sound got extremely loud today, oil light came on on dashboard. Oil seemed to be completely empty even though I filled it up 2 weeks ago. Filled with oil again, still knocking very loud and barely any power but check engine light never came on. Have I blown my engine? Is the car even worth fixing?

My car has 215000 miles.
M

Experienced mechanics share their insights in answering this question :
White smoke out of the tailpipe and the engine being low on oil, indicates the engine is consuming (burning) the oil. It can be anything from a failed head gasket, cracked head, valve seals, or worn piston rings. You say the oil level was fine 2 weeks prior to this. How many miles were driven in those 2 weeks ? If it’s less than 1,000 miles, then that is fairly serious oil consumption. Considering the age and mileage of the vehicle, that might mean an engine rebuild / replacement. That can cost $2000-$4000 depending on who does the work, the cost of the engine,etc.

Is it worth fixing ? Well that is a subjective question. I can give you opinions from experience. The value of the vehicle may not equal the cost of a replacement engine. If that’s of no concern to you and the rest of the vehicle is in good shape, then spending that amount of money on the car may be worth it to you. On the flip side, you may be able to sell the car for a minimal amount, just to make something from it, and take the amount that a replacement engine would cost and put it towards the purchase of a newer or lower mileage vehicle.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

Bad Sway Bar Link: A vehicle`s sway bar or anti-roll bar, helps reduce body roll while cornering. Sway bars can help keep a vehicle from rolling over when going around a sharp corner. If the sway bar breaks or is damaged it may produce a clunking or knocking sound, especially when going over bumps.
One of the most common causes of engine knocking is low oil. If your car has been using more oil than usual, it`s a good idea to top it off. You can also try using a higher-quality oil, as this can help reduce engine wear. It`s important to regularly change your oil because dirty oil can also cause knocking.
What to do – Check all suspension components, steering column, and your exhaust system. If you drive over bumps or potholes and you hear knocking noises from under your car, there`s a strong chance it`s your suspension or shock absorbers. The suspension consists of many parts, so have a mechanic isolate the issue.
If the smooth rumble you`re used to coming from your engine is replaced with a repetitive tapping or pinging sound that becomes louder and faster as you accelerate, that`s a classic sign of engine knock.
Knocking can damage the surface of the piston, the cylinder walls or the crankshaft bearings, all of which are expensive to repair. Modern computer-controlled injection systems can correct your fuel mixture to prevent knocking, but at the cost of engine performance.
Low oil pressure can be caused by a clogged line, a bad pump, or a clogged filter. The low oil pressure would rob the engine of the oil it needs and produce a knocking sound.
Adding more oil will make the noise go away, but it won`t solve the underlying cause of the noisy engine – the oil leak.
A knocking sound when going over bumps can indicate a problem with the suspension struts. There might be a clanking sound of metal hitting metal when you go over bumps. This could show the rubber bushes that join parts of the suspension have failed.
Once an engine starts to knock, the rod can fracture without warning. It could be the next time you start it in your driveway, or it could keep going for six months. Eventually though, the engine will blow and you`ll be stranded somewhere.
Spark Plugs That Are Worn or Misfiring

If your spark plugs are overdue for replacement, your engine knock could be attributed to that and you may also lose engine power.

A puddle of amber, brown or black liquid under your car is probably engine oil, but if you want to be sure get close enough to touch it. If it feels slick and it`s hard to get off your fingers, it`s almost certainly oil.
If you do experience a knocking sound coming from your engine, it`s important to stop driving immediately and have a qualified mechanic diagnose and repair the problem. Allowing rod knock to continue unchecked can lead to serious damage to your engine and should be taken seriously.
A: If you see a puddle of greasy-looking liquid on the ground after your vehicle has been parked for a while, then that means you have an oil pan leak, which usually indicates holes in your car`s oil pan or gaskets. Take your vehicle to a shop straight away.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Soft knocking sound, goes through a lot of oil but I don’t ever see it "leaking" from anywhere.
ANSWER : White smoke out of the tailpipe and the engine being low on oil, indicates the engine is consuming (burning) the oil. It can be anything from a failed head gasket, cracked head, valve seals, or worn piston rings. You say the oil level was fine 2 weeks prior to this. How many miles were driven in those 2 weeks ? If it’s less than 1,000 miles, then that is fairly serious oil consumption. Considering the age and mileage of the vehicle, that might mean an engine rebuild / replacement. That can cost $2000-$4000 depending on who does the work, the cost of the engine,etc.

Is it worth fixing ? Well that is a subjective question. I can give you opinions from experience. The value of the vehicle may not equal the cost of a replacement engine. If that’s of no concern to you and the rest of the vehicle is in good shape, then spending that amount of money on the car may be worth it to you. On the flip side, you may be able to sell the car for a minimal amount, just to make something from it, and take the amount that a replacement engine would cost and put it towards the purchase of a newer or lower mileage vehicle.

lost all oil pressure, replaced the oil pump, low oil sensor, oil pressure sensor, oil pan gasket,
ANSWER : The fuel pump will not stay on if you loose oil pressure. This is why it is shutting off. The loss of oil pressure may be from bad crankshaft bearings or camshaft bearings. The engine oil pan should be removed and the oil pump needs to be checked to ensure that you put in the pick up tube seal to the pump and connected the pump to the block. Then remove at least one main bearing cap and inspect the bearings for excessive wear and crankshaft damage. If you need some help with this, consider YourMechanic, as a certified technician can help diagnose the issue with your oil pressure firsthand and help you fix it accordingly.

I have an engine knock and my oil pressure guage is reading high, then stops shortly after starting to drive.
ANSWER : Hello,
You may want to inspect your oil pump to see if it may not be causing the problem. If it is not pumping or circulating oil properly, it may also cause this type of increase in oil pressure that may be sporadic as you describe. When you first start the engine, the oil pump needs to work a bit harder than normal at first the get the oil circulated through the motor to all of the places it needs to go as the oil is much thicker when it is cold. As the engine warms up, the oil becomes thinner and flows a bit easier, which may be what causes the pressure to come back down once it is warmed up. Please feel free to reach out to us here at YourMechanic or schedule an appointment to have one of our qualified mechanics come to your location to diagnose and inspect your truck.

Oil consumption. Burning oil. Oil light turns up on idle.
ANSWER : Hi there, thanks for writing in. The valve stem seals are the most common cause of this on your engine. When they fail, it requires that the cylinder heads be removed and rebuilt to fix it. The piston rings can also cause this but they are not as common. Unfortunately there is not anything, not even heavier oil that will fix this. You will need to have the heads rebuilt.

My engine has a ticking knocking type of sound. It runs fine not buring oil or losing coolent. Sounds like the valves taping
ANSWER : On a 1998 engine with 147,000 miles, the noise could come from anywhere. I typically check the engine oil level when cool to verify it is correct. Then, I run the engine for 5 minutes, shut it off, and check the engine oil level again.

If after running it for a short time and the engine oil level is lower, then it is likely you have a sludge build-up in your oil return passages preventing oil from draining back to the oil pan. If so, maybe an engine oil flush is in order. At the mileage, sometimes an oil flush may do harm to your piston rings or may help. You never really know.

If the oil level is correct after running the engine, you should have an oil pressure gauge connected to the engine to verify that it is within specifications to factory numbers to verify the oil pump is working properly.

An engine tapping noise could be anything from connecting rods on the crankshaft to an engine valve lifter. If the noise is a knock-knock in a repetitive motion at a slow speed, I would suspect lower engine problem, like a connecting rod (which requires a complete engine rebuild). If the noise is at a higher frequency, then I would think you have a valve issue which could be repaired at a much lower cost.

Based upon mileage, the feeling of how the engine runs, engine codes (if any), and an unknown level of maintenance, it is difficult to determine the exact issue. You may need an engine repair, a new engine, more oil, an oil pump, or just live with it. I’d have a certified mechanic take a look at it to diagnose and fix the sound that’s coming from your engine.

Engine knock, burned a lot of oil
ANSWER : The ticking sound is caused by the valves in the engine experiencing a low oil condition, the lower the oil gets the louder the noise. This is a well-documented problem for this series where the vehicle will excessively consume oil, sometimes as much as a quart every 2,000 miles! GM states this is due to faulty piston rings, which allow the oil to slip past the oil ring and enter the combustion area where it is burned along with the fuel, resulting in a severe oil loss, with no evidence of a leak, and reduced fuel economy (oil and gas mixed together do not burn well). You can reference Technical Service Bulletin (TSB) #01-06-01-011H, which addresses the issue of excessive oil consumption. The bottom line is that the pistons and rings all need to be replaced to correct this issue. While GM has been aware of the issue for some time, as evidenced by many internal memo’s, they are often slow to fix the issue at the dealership level. Make sure you check you oil level every 1,000 miles or so until the problem is resolved or you run the risk of running your engine dry and causing severe damage. If you have a warranty, have this issue addressed as soon as possible as it will not go away without proper repair. Even if you have no warranty, I recommend going into your local dealership to see what they are able to do, be persistent.

My car is leaking oil i got an oil change for it last month but it is still leaking oil what will cause my car to leak oil ?
ANSWER : Most older cars have oil leaks. Sealing technology has just not kept up with mechanical improvements to engines so much so that leaks often kill engines rather than mechanical problems. So, it is not unexpected at all to have an, indeed many, oil leaks on a 23 year old car. Oil leaks vary hugely in terms of severity and priority of repair. Oil leaking onto a hot engine manifold is the worst case (the oil can start a fire; at best, you are left breathing oil fumes in the cabin, as the oil burns off of the manifold) while de minimus seepage of oil at the oil drain plug or oil pan gasket, while annoying and messy, if limited enough is not an emergency. Some leaks are easy to repair, while others literally require the engine to be removed just to get physical access to all the leak points. In your circumstance, if you smell burning oil, oil is probably leaking onto a hot engine part such as the exhaust manifold. A certified Mechanic, dispatched by YourMechanic right to your location, can perform an oil leak diagnostic and then let you know of your repair options and costs.

As far as the check engine light, that is not related to the oil leak(s). If you request a check engine light diagnostic, a certified mechanic from YourMechanic would use a code scanner to retrieve the specific diagnostic trouble code(s) from your car’s PCM that have caused the check engine light to illuminate. Using those codes, the appropriate individual vehicle components or sub-systems (often a sensor, circuit, and the like) are then carefully tested, based on specifications set forth in your car’s Factory Service Manual, to pinpoint the cause of the fault or the reason why the check engine light has illuminated. Once the faulty part or component is identified, it is explained to your satisfaction and the mechanic will let you know of the cost to repair. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

Oil still leaking after I changed oil filter
ANSWER : Unless there is an imperfection (e.g., serious pitting or irregularities) on the engine mounting base for the filter gasket, the leak is probably not at the filter. There are other adjacent potential leak spots such as the oil pan gasket, oil pressure sending unit and so forth. If the leak is significant at all, merely thoroughly cleaning the suspect area and running the engine while looking for the leak should be sufficient. If you still can’t find the leak origin, a UV visible dye can be added to the engine oil which will then make the leak point visible using a detection light. If you want these steps performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an oil leak diagnostic and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.