Bad oil pump ?

This sounds like an oil pressure problem, The very first thing I would do is if it's almost due for an oil change do it now, if not replace the oil filter it actually has a diaphragm in it to keep the oil from leaking back into the engine when the engine is off causing the oil pump to have to fill the filter before lubricating the engine causing the lifters to rap and the connecting rods to knock, remember to add oil if you just change the filter. If the engine has a lot of miles you might want to consider an oil treatment like SLICK 50 it coats the friction surfaces and prevents wear. I hope this helps. Take care.

How loud is the knock?

Typically, a quite ticking sound is associated with a sticky lifter and a louder knock is associated with a piston rod going bad.

In the case of a lifter ticking, it typically indicates wear or a sticky lifter which can be addressed with the proper oil additive.

You can isolate the noise to it's actual location with a mechanics stethoscope. Sometimes, just holding a stick up to the engine and placing your ear next to it will help you isolate it as well.

Regardless of whether you have a sticky lifter or a worn piston rod, the only way to address the issue is to tear down the engine and replace the worn part or parts.

If you're going to tear the engine down, then you may as well do a complete overhaul while your at it. The end result will be a more responsive, cleaner running engine.

Takes about 1 1/2 hours to figure it out. I can remove both valve covers in about an hour. 15 to 20 minutes to see which one is bad, if one of them are bad. Lifters and rockers arms usually make a ticking sound. Knocking is usually the piston rod. could be bearings at the crank or the wrist pin at the top of the rod. I've seen valve springs broken and only cause a ticking noise.

1. Engine Noise. With a bad oil pump sufficient engine oil will not get to all parts of the engine, especially the top end, and you will get engine noise with metal parts that would normally be lubricated and quiet knocking due to metal to metal contact. Engines with hydraulic lifters that become noisy can be a sign that they have insufficient oil supply. In addition to the hydraulic lifters, your valve train may begin to make noise if your oil pump begins to fail. Valve train components need to be properly lubricated as well. A bad oil pump can result in a lot of additional noise from your valve train system.

2. Higher engine temperature. Poor lubrication because of poor oil flow generated from the pump will cause friction in the engine and the engine temperature will rise. Good oil flow is essential for lubrication and reducing friction to a minimum.

3. Low oil pressure. The oil pump generates oil flow through the engine but tolerances between metal parts produce the oil pressure. Very worn engine bearings will result in low oil pressure. Thus a worn engine will have low oil pressure even though the oil pump may be fine and there is no issue with the oil pressure relief valve either. However you will also experience low oil pressure due to a failing oil pump because poor oil flow will also result in lower oil pressure.

If your oil pressure warning light has been triggered in your engine, the causes of the low pressure need to be properly investigated because the problem may not be with the oil pump. People replace oil pumps assuming that is always the problem and then still have low oil pressure because the pump was not the problem to begin with.

Hi Mary:
Squeaks from the engine area will be coming from moving non-lubricated parts.
Try checking:
- Serpentine belt. These will squeak like crazy if they have anti-freeze on them.
- Water pump. They have a bushing with a seal. Even if the seal is still not leaking, the bushing can be worn and will make some noise.
- Alternator, power steering pump, air conditioning pump can all have similar broblems with bearings.
MECHANICS TRICK! Use a stethescope to listen near the part you're checking. This is a mechanics stethescope, not the doctors kind. I just use a 2 ft long piece of 1/2" wood dowell. Hold it at one end with my thumb over the end, put my thumb against my ear, and touch the part that I'm checking. Obviously, the motor has to be running while you do this, so STAY SAFE! Do not let the dowell touch any moving parts. No kidding. Your motor can talk to you.

ok on todays automobiles the gas cap does more than just seal the gas tank. Now they run a return line to the tank. this does 2 things. it returns un used fuel and vapors back to the tank , and it pressurizes the tank to help improve the fuel pump.

Now as it is possible running without the gas cap may cause problems I am not 100 % positive that is your only problem.

It sound like the knock sensor is detecting the knock you mentioned and is trying to retard the timing to fix it . In doing so it has retarded it to far causing the engine to loose power and eventually stall. I would first replace the gas cap. then run a good gas additive to a full tank of gas to clean out any water and dirt that may have gotten into the tank while the cap was off. now the issue of the knock as you described. is it a knock or a ping? A knocking sound is loud metallic hammering noise. a ping is a ting not very loud. if it is a loud metallic sound I would have a reputable mechanic check it soon, as it could be a serious issue. Ping can be caused by bad or weak gas or cheap low octane gas. I would run a mid grade gas in it and see if it fixed the issue.

I can't tell what kind of car you have, but off the cuff it sounds like you have a pulley with a bearing inside that is failing. There are several pulleys that it could be, here are their names and I've listed them according to the most probable to the least probable for most everyday American cars. Idler pulley, alternator pulley, tensioner pulley, power steering pulley, and air conditioning compressor pulley. Whatever you do, it sound like it needs RIGHT NOW attention.
Be blessed.

might be the valves have been damaged running without oil
- or the crankshaft / camshaft / main bearings
most probably you have to let the engine be rebuilt by a mechanic
(expect cost of more than US$ 2.000)
or get another (used) engine at a scrapyard

Doesn't sound good. Check oil level. Also check for metal in the oil once you pull the dipstick. A loud knocking noise is a sign of a blown engine may be you spun a rod in which case you would need engine replacement or rebuild

It all depends how loud the knock is. A tapping valve can be caused by low oil level, or dirty oil. Topping up or changing oil will solve the problem. A really loud valve tapping is abnormal. Cars sometimes make what you call a spark knock when accelerating hard. Extremely loud knock coming from deep within the engine is a bad sign, which means the engine has failed. Further examination would reveal metallic residue on the dipstick.