Hyundai Sonata 2000 150,000 miles

I started getting a noise in the engine that I would describe as "light", and "enginey"

Here is a video with sound.


The sound becomes more frequent as the RPM increases. So it probably has to do with some rotational portion of the engine.

Additionally, I'm not sure if this is relevant, but the airbag light came on a few weeks before this started happening. I think the air escaped probably. Again, not sure if this has anything to do with the engine sound.


an interesting post about hydraulic valves, oil changes, low oil or leak, and dirty oil http://ask.metafilter.com/248194/Can-I-drive-my-car-if-the-engine-has-Hydraulic-Lifter-Ticking


It turned out my engine oil was super low. The dip stick didn't even read anything. I put half a quart of whatever I had left in, and it still didn't read on the dipstick. I can't recall if the engine temperature reading went significantly above that "50%" mark while I was driving it.

Maybe it's tapping because the oil is just low? But why would it get so low suddenly? There must be a leak. Hopefully not a head gasket/plenum leak.

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    If your oil was that low, then yes, that can make the noise. Please post that as an answer and check it as such! – Pᴀᴜʟsᴛᴇʀ2 Mar 31 '16 at 8:26
  • I'm going to get it checked out, oil changed, and see if it still makes the noise, or if there's some other problem. – ahnbizcad Mar 31 '16 at 8:35

it sounds like valves

Your valves are at the top of the motor under the black cover.

They are reciprocating devices, they move in and out and are operated by a camshaft that is spinning at half the RPM of the crankshaft.

As your cam rides on top of a tappet or 'bucket' the clearance between the cam and the tappet/bucket can increase or decrease over time.

If the clearence increases too much you can here a ticking noise as the cam comes around and slaps the top of the tappet/bucket.

enter image description here

get your valves adjusted

The clearance increased too much. The sound is the cam lobe hitting the tappet. This is normal engine maintenance. It's called a 'valve adjustment'.

  • Thank you so much! Seriously. Your expertise and explanation are so on-point. – ahnbizcad Mar 30 '16 at 8:33
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    You may not want to award me the answer just yet. If you wait more people might answer with better answers but I believe I am correct. Thanks for posting that video. Being able to hear the sound is important. Cheers! :-) – DucatiKiller Mar 30 '16 at 8:34
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    One question. The tappet clearance increasing too much causes the cam shaft to hit the tappet? You didn't mean if the clearance was too small, did you? I'm not really sure about the geometry so I'm just going by the logic based on the little info I have. – ahnbizcad Mar 30 '16 at 8:38
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    It uses hydrodynamic lubrication. If the clearance is within spec the lobe drifts across the tappet with a layer of oil between the cam and the tappet thereby making it sound much quieter. When you get increased clearance the lobe has a steeper angle when it 'hits' the tappet which makes the sound. – DucatiKiller Mar 30 '16 at 8:40
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    It's the engine oil and one of the reasons it's important to change it regularly. – DucatiKiller Mar 30 '16 at 8:44

While @DucatiKiller is most likely correct, there is another possible reason for this noise, that being a leaking exhaust manifold. If the exhaust manifold is leaking at the head, it will make an almost indistinguishable noise from that of the tappets. It too rises and falls with engine RPM, just like tappet noise. It comes from the same basic location (head area) as the tappet noise. It is at least something to check out, but looking at your video the Hyundai engine's exhaust manifold looks to be at the back of the engine (well covered up). What you'd be looking for is black soot (carbon tracking) around the exhaust manifold at the head. This condition will also cause the vehicle to attain less fuel mileage due to improper O2 sensor readings (false lean reading due to fresh air being brought in at these leaking areas). Before you tear or have the top end torn apart, you'll want to double check these gaskets.

EDIT: I just realized your Sonata has a V6, which means it has exhaust manifolds on both the front and the back of the engine. I guess I'm just pointing out the obvious.

  • you guys re the best – ahnbizcad Mar 30 '16 at 17:57
  • This is like the doctor telling me it's a benign growth, but it's possible that it's cancer. just check it out. hahaha =] – ahnbizcad Mar 30 '16 at 18:02
  • If it was a gasket problem there would probably be an error code? There are no error codes except for p0711 transmission fluid temperature sensor circuit. – ahnbizcad Mar 30 '16 at 18:19
  • @ahnbizcad - No, there wouldn't be a code. It's amazing how closely exhaust leaks sound like tappet noise. You may try an automotive stethoscope to pinpoint where the noise is coming from. – Pᴀᴜʟsᴛᴇʀ2 Mar 30 '16 at 20:29
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    @ahnbizcad - No, I wouldn't think that would be an automatic indication. The best tell tale sign is looking for the soot traces at the head. If there there, it's pretty easy to see (if they're on top, that is). – Pᴀᴜʟsᴛᴇʀ2 Mar 30 '16 at 21:37

The oil was low as fk.

No lubrication meant the cam would not glide, but result in more of an impact, resulting in tapping sounds.

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    There you have it. I hope we contributed to the solution. Cheers! – DucatiKiller Apr 1 '16 at 21:51
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    Let's not stop at "the oil was low". There's a reason the oil was low. Leaking head gasket, cracked head, worn cylinders/pistons causing blow-by, oil pan/plug/gasket leak, trans mount gasket leak, shaft seal leak, filter seal leak, worn valve stem seals, etc. That oil went somewhere. I'd look into it. 150k miles is low for a 2000 but it only takes a short time for excessive heat or gritty material to cause blow-by. An excessively clogged filter can prevent oil from getting to many parts of the engine, resulting in friction and eventually wear that can cause blow-by, valve stem leakage etc. – Dexter Apr 12 '16 at 6:17
  • Dexter, so much win. That's great info. Thanks for sharing. I will look into it. My plan was to do "steam cleaning" as they recommended, and then drive it around for a while to see where the leak is. I suppose I could buy some engine marker fluid (pretty sure that's not what they call it). I haven't gotten around to it. – ahnbizcad Apr 12 '16 at 19:25

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