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Discussion Starter #1
I don't know about the 2.4, but several people here and on other Kia forums have mentioned engine noise, such as valve clatter, diesel sound, and a knocking sound at warm idle that comes and goes. These are not sounds associated with injector ticking or gas(pinging).

Yeh, they use mechanical lfters, but it's the irregular valve clatter and/or knocking noise that is a concern, IMO.

Example 1: Cold start quiet, but as it starts to come off high idle there is what appears to be valve noise.

Example 2: At warm idle only(not while driving and not above 1000 rpm), there is an irregular engine knocking sound. It's a knock, knock-knock...or clack, clack-clack. It's intermittant, not there at all sometimes.

Maybe the variable valve timing has something to do with it, maybe oil flow. I changed the factory oil at 1000 miles, using 5w-30, using a Kia filter. I noticed with the 5w-30 that the engine was quieter while driving(under load), but no improvement on cold start or the occasional knocking sound.

Any thoughts?...
 

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I wish there were a way to quantify the loudness--several other folks have posted the same issue. At warm idle, i can hear some very faint clatter from the valve train, but not a loud knocking or clacking. As a matter of fact, there have been several occasions where I have been sitting at drive thru pickups---sometimes I'll turn off the engine to save fuel--other times I won't---and I'll forget that I have the engine running sometimes and hit the starter and grind the starter gear. So, with that in mind, I would say that my engine runs so quiet that I can't hear it running. The only time that I can even faintly hear this clatter is when I am inside of my garage where it is very quiet and the sound of the engine is echoing off the walls---

I did have a Chevy V8 high performance engine that would knock REALLY loud when I would come down from a sustained high RPM run (say on the freeway) back to idle. I know that this was caused by oil starvation to the lower engine rods and bearings---it would quiet back down when the oil drained back to the pan from the upper engine galleries---
 

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Discussion Starter #3
I wish there were a way to quantify the loudness--several other folks have posted the same issue. At warm idle, i can hear some very faint clatter from the valve train, but not a loud knocking or clacking. As a matter of fact, there have been several occasions where I have been sitting at drive thru pickups---sometimes I'll turn off the engine to save fuel--other times I won't---and I'll forget that I have the engine running sometimes and hit the starter and grind the starter gear. So, with that in mind, I would say that my engine runs so quiet that I can't hear it running. The only time that I can even faintly hear this clatter is when I am inside of my garage where it is very quiet and the sound of the engine is echoing off the walls---

I did have a Chevy V8 high performance engine that would knock REALLY loud when I would come down from a sustained high RPM run (say on the freeway) back to idle. I know that this was caused by oil starvation to the lower engine rods and bearings---it would quiet back down when the oil drained back to the pan from the upper engine galleries---
I agree that it's always tricky to quantify engine noises, especially knocking sounds.

I wouldn't describe it as a loud knocking, but what I'm hearing on mine is a little more than valve clatter, although I have that too. I can hear it most clearly inside the garage, as you said. But I can also hear it at idle at a stop light or in a parking lot, when it's there.

That's the thing, it's NOT there all the time. I can start it up warm and no knocking noise at idle. I can then start it warm 15 minutes later, and the knocking sound is there. It does seem to dissipate after a minute or so of idling, which is another odd thing about it.

What I'm trying to do with this engine noise topic is to see if some other owners are experiencing the same engine noise(s) in their Forte's. If so, I would be less concerned. I now have it on record with the dealer at 1300 miles. So, if the engine develops a problem, they can refer to the noise complaint made very early after purchase.

The engine is surprisingly quiet under acceleration and load, especially after switching to the 5w-30 oil. It's just at idle where they seem to be noisy. Sounds kind of junky at idle for a new car. And not talking about the mechanical lifters being a little more noisy. Or the injectors. That is normal and typical. This is valve clatter and/or the separate irregular knocking sound.
 

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Well, I just had my oil changed at the dealer just last week--the dealer uses 10W-30 Castrol GTX bulk oil. I live in S. Louisiana---we never see temps below 25 degrees F--usually not below 40 degrees F---well within the temp range specified by KIA for the 10W-30 oil--not nearly cold enough to warrant use of a 5W oil.

I noticed no difference between the factory oil and the Castrol 10W-30 as far as my engine sounds go--about the same amount of faint valve clatter--so I doubt that yours (or others with this issue) has much to do with oil viscosity.

One thing to (maybe) consider--is that the oil pump is cavitating at times (for some reason--possibly foamed up oil?) and vapor locking the pump so that oil is not getting pumped under enough pressure to the upper galleys?

Another thing could be a condition known as "piston slap"--this can occur when the clearance between a piston and a rod pin is slightly off specification. What happens in this case is that when the piston changes direction (usually on the downward power stroke) the loose fitting pin allows the piston to "slap" the side of the cylinder bore, causing a knock or clack. Pretty rare in high tolerance modern engines, but could be a long shot.

Keep us posted---
 

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I've had my Forte EX for less than a week, and I think I heard the sound you're describing once while waiting at a stop light... never again though.
 

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Discussion Starter #6
Well, I just had my oil changed at the dealer just last week--the dealer uses 10W-30 Castrol GTX bulk oil. I live in S. Louisiana---we never see temps below 25 degrees F--usually not below 40 degrees F---well within the temp range specified by KIA for the 10W-30 oil--not nearly cold enough to warrant use of a 5W oil.

I noticed no difference between the factory oil and the Castrol 10W-30 as far as my engine sounds go--about the same amount of faint valve clatter--so I doubt that yours (or others with this issue) has much to do with oil viscosity.

One thing to (maybe) consider--is that the oil pump is cavitating at times (for some reason--possibly foamed up oil?) and vapor locking the pump so that oil is not getting pumped under enough pressure to the upper galleys?

Another thing could be a condition known as "piston slap"--this can occur when the clearance between a piston and a rod pin is slightly off specification. What happens in this case is that when the piston changes direction (usually on the downward power stroke) the loose fitting pin allows the piston to "slap" the side of the cylinder bore, causing a knock or clack. Pretty rare in high tolerance modern engines, but could be a long shot.

Keep us posted---
You're right, according to the owners manual, 5w-20, 5w-30, and 10w-30 are all approved oils. It depends on your areas temp range. I live in Calif where it doesn't get that cold.

I sure hope there is no oil foaming going on. That's usually associted with overfilling an engine with oil, isn't it? I'd be more suspicious of the variable valve timing 'oil control valve'. That's the solenoid that controls oil flow to the cam phasers which vary the valve timing. In fact, Kia has a TSB out on that, but not for noise...just rough idle and misfires. My idle is glass smooth and no misfires, performance is strong.

Yes, piston slap is a possibility. Although under warm conditions, I don't know.
 

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Discussion Starter #7
I've had my Forte EX for less than a week, and I think I heard the sound you're describing once while waiting at a stop light... never again though.
Yeh, it seems to come and go. Listen for it again, maybe while at warm idle in a garage.
 

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You're right, according to the owners manual, 5w-20, 5w-30, and 10w-30 are all approved oils. It depends on your areas temp range. I live in Calif where it doesn't get that cold.

I sure hope there is no oil foaming going on. That's usually associted with overfilling an engine with oil, isn't it? I'd be more suspicious of the variable valve timing 'oil control valve'. That's the solenoid that controls oil flow to the cam phasers which vary the valve timing. In fact, Kia has a TSB out on that, but not for noise...just rough idle and misfires. My idle is glass smooth and no misfires, performance is strong.

Yes, piston slap is a possibility. Although under warm conditions, I don't know.
I know that it should never go below 0 degrees F in California---why don't you try the 10W-30 viscosity oil and see if it stops? Worth a try--especially if you're getting close to oil change time anyway--
 

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Discussion Starter #9
I know that it should never go below 0 degrees F in California---why don't you try the 10W-30 viscosity oil and see if it stops? Worth a try--especially if you're getting close to oil change time anyway--
I figure there should be no difference when engine/oil is fully warm, both being a 30W. But I like the 5w-30 over the 10w-30 for cold start oil circulation. I may try 10w-30 next oil change though, as it will take me into the summer.

In the mountains of California it can get well below 0 degrees. I lived in Lake Tahoe for 4 years and we would routinely see morning low temps of -10F...even -20F on occasion in the winter. I only used synthetic oil in my cars at the time.
 

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Silver, I'm glad you brought this up so I at least know I'm not alone on this. I share the same concerns regarding the knocking noise. I can't offer any advice on the issue because I know very little about this but I thought I'd at least post a reply.

I don't hear it all the time, but every now and then when I idle I'll hear it and it sounds like junk. It reminds me of the sound when a car is low on oil or needs an oil change. I just recently got an oil change at 3500k from the dealer and I heard it before and I still continue to hear it.
 

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Discussion Starter #11
Subtle,

Yeh, we are not alone in this light knocking sound that comes and goes it seems. Others have mentioned it in other threads here.

Like you said, sometimes I hear it at idle, other times it's totally absent and idle is quiet...or normal sounding.

BTW, I heard it from day one basically, and changing oil to 5w-30 didn't affect it...although the engine does run smoother and quieter on 5w-30 compared to the factory fill 5w-20. I noticed that right after the oil change.
 

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Discussion Starter #13
Someone mentioned on another forum that the knocking sound is the ESC performing a self-check. I blew it off at the time, but I'm beginning to think maybe it is something like that.

The fact that it's not there at all sometimes rules out valve adjustment, valvetrain problem, piston rod bearing, main bearings, acessory pulleys, etc.
 

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The electronic stability control? I'm not sure why it would make that knocking noise but perhaps. Come to think of it, most of the time I do it hear it is when I'm in my driveway which is a decent slope. I'll try leaving the ESC off for a while and see if I hear it anymore.
 

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Got a question...is there any possibility that the noise you guys/gals are describing could be coming from the fuel evaporation system canister under the car? Can the Kia system make a noise? I have not heard the sounds you are describing, however, on the Chevy Cobalt there is a knocking sound that comes from the fuel evaporation system canister when it purges on that car. It usually "pops" 2 or 3 times in a row.
 

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Discussion Starter #16
Got a question...is there any possibility that the noise you guys/gals are describing could be coming from the fuel evaporation system canister under the car? Can the Kia system make a noise? I have not heard the sounds you are describing, however, on the Chevy Cobalt there is a knocking sound that comes from the fuel evaporation system canister when it purges on that car. It usually "pops" 2 or 3 times in a row.
I've heard of that being a possibility for the knocking sound on other cars, so it could be the case with the Kia's.

I heard the sound again today briefly. It's really a clack-clack, clack-clack-clack noise.
 

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Discussion Starter #17
The electronic stability control? I'm not sure why it would make that knocking noise but perhaps. Come to think of it, most of the time I do it hear it is when I'm in my driveway which is a decent slope. I'll try leaving the ESC off for a while and see if I hear it anymore.
Good idea leaving the ESC off to see if the noise is still there. I'm going to try that too. It's worth a shot.

I was pretty concerned when I fist heard the knocking sound on a brand new car. But the fact that several others are experiencing it on their Forte's and that it isn't there most of the time has made it less of a worry.
 

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Some of the posters on the Cobalt sites described the sound as if someone was locked in the trunk knocking on something. I've heard that sound in a Cobalt but not in either of my Fortes.
 

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My Forte Koup SX is only 1 week old and has about 400km on the odometer. I was showing it off to my brother on the weekend and popped the hood while it was at idle. I heard a definite "clacking" noise which seemed to be coming from the overhead cam area. Remember noisy tappets from Chevy's? Sounded like that. I don't hear it while driving as the cabin is very, very quiet. I have a service appt scheduled in a couple of weeks and will ask the dealership about it then.
 

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I believe this is normal in 4cyl engines. I have a 2.4 2006 PT Cruiser and has the same sound. I know someone who has a 2009 Honda Accord , same sound. I don't believe its something to worry about. And I too can't hear it inside the cabin, only while standing in front of the car with engine running.
 
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