reducing the rattling from 89 sonata engine

I had a Vega with similiar noise...they say heat riser valve makes it. Same for sonata.? It does it on accelration and on hills. It is a rattle or chatter like a diesel engine.
Opinions what to look for and fix
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wrenchwench wrote:

That sounds more like pre-ignition or detonation if it happens only under load and sounds like a diesel.
Matt
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I have 2005 Sonata GLS V6 automatic, and similar sounding issue: The engine sounds like a diesel, especially in low gear (second gear, going uphill at 30 mph, about 2200 RPM), when cold. When the engine reaches normal operating temps, the noise goes away.
Also, even when the engine is cold, there is no such noise when idling, or when I take my foot of the gas (say when going downhill).
Now that the weather is warmer, the noise disappears much more quickly.
Do you think this is normal, or do you have any recommendations on what I should check?
Thanks.
Sinan
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A. Sinan Unur wrote:

I doubt it is normal, but my Sonata is a 4 cylinder and I don't have any familiarity with the V-6. I'd have your dealer take a look at it since it still should be under warranty.
Matt
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I have the V6 and I can tell you that the sound definitely isn't normal.
What happens to the power level when this noise is occuring? Second gear at 30 MPH is about, what, 3000-4000 RPM? And you are getting a deisel sound at that RPM? Have you tired a different gasoline supplier? Is it possible this is a transmission noise?
Sorry for all the questions. But that noise certainly doesn't seem right to me.
Eric
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...
First, thank you both for your comments.
Sorry, disregard the former RPM figure. Going uphill in second gear, RPM near 3000. Going straight in third or fourth gear. RPM right around 2000. Only when the engine is cold. I wait for the initial high idle after ignition to settle down before driving away ... no extended warm- up.

From inside the car, it does sound like a diesel.

I buy my gas at many different places, depending on who's cheapest basically: Sunoco, Hess, Mobil in Ithaca, NY, Exxon or Citgo in the Poconos, various stations around Jersey City.

I am no expert when it comes to cars, but would that go away when the engine warms up?

I appreciate the questions and feedback.

I'll get in touch with the dealer some time during the week. In the mean time, I would appreciate further feedback in case anyone thinks of something.
Thank you again.
Sinan
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Without hearing it, the suggestion of pre-ignition shoulds plausible. Easy way to tell; run a tank of hi-test, er premium gas. It should help if it's pre-ignition

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It's a fairly simple matter to pull the valve cover and take the jet valves out to see if they're clogged. If they are indeed clogged, broken, or burned, you should replaced them.
If I recall correctly, this engine also had a significant carboning problem. This could also be contributing to your problem.
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