Knocking engine sound - is it serious?

[375ponies]

Hi,

Recently discovered a new sound coming from my engine. Here is a YouTube clip: https://www.youtube.com/watch?v=h7R15C2X02k&feature=youtu.be

I've searched these forums and it's quite scary, in most cases people were saying that they had to heavily rebuild or even completely replace the engine. Is that true? I don't have any of the factory warranty left, only some garbage third-party one.

Anyone knows what is causing this and if it's possible to diagnose it so that I could work something out with the warranty?

 

[Mark_888]

There was a problem with the early Tau V8's, especially if someone started the car and turned it off within a very short time, and then next time they started it some of the engine components were in the wrong position, and a restart caused moderate to serious damage to the engine.

As far as the Canadian warranty, I assume it is expired (no extended drivetrain warranty in Canada). Not sure why you think the 3rd party warranty is worthless, and it may be your only recourse at this point.

 

[landtuna]

If it is the deep bass knocking sound you refer to I am going to guess (and it is a guess) it is something in the lower end - rod or crank bearing slap or something similar. Other things could be causing that sound though. Best to take it to a good engine shop and see what they say.

 

[homeofstone]

Have after market oil filters been used? Sounds like a rod and could be serious. You could try a 10 w 30 or 10 w 40 synthetic oil and make sure you use hyundai oil filter.

 

[375ponies]

Just a quick update - the car was in the shop for a week or so (not under warranty, third-party), but they couldn't find the reason. After they changed oil to 5-30 the knocking sound is gone i think. Still, even if it's gone, I doubt it's a real fix.

Now i'm having another problem with non working brake lights I like the car but I'm starting to consider whether I should keep it.

 

[Gunkk]

The brake lights is probably the diode in the rear (affects just the lights) or the brake switch at the pedal (affects other things like shift lock, cruise control, etc.). Both are easy and cheap to fix. Diodes are about $10 and a snap-in. There are many posts on this site, some with really nice pictures and guides for a DIY fix.

RE: the low pictch knocking in the OP video... If you can feel the thump as much as hear it, it then it's probably a crank bearing. Since it's not on YouFeelTube, my money is still on a bearing though (sounds like one thump per crank rotation). Change in oil is probably raising pressure/viscosity enough to allowing the crank to hydraulically float past the bump in the bearing at idle. But it probably does not under load, which may be hard to tell when driving. That's my 2 cents. Unless the engine is totally torn down and all friction surfaces of crank, cam, bearings and lifters/rods inspected, you probably will never be able to see it.