Is this conn rod knock?

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2007 I4 cyl 2.0 liter Kia Sportage automatic with 53,000 miles. Noticed a few weeks ago some metallic knocking sounds from the engine when accelerating slowly. Sounds like marbles dropping onto a metal plate. Happens only when accelerating from rest or 5mph till 20 mph. (or maybe it's still there but I don't hear it bec road and engine noise drown it out) Never happens when I take my foot off the gas pedal. It is worst when the aircon is on and car's going up a ramp at 1st gear and gets louder if I speed up slowly while going up said ramp. The manual calls for 87 octane gas and that's what I use. I filled up a few days ago with 91 octane but knock seems unchanged. Other than that, car runs fine and no check engine light. What do you think, guys?
 
Does it make noise in park at idle or off idle? You could disable one ignition coil or fuel injector at a time by disconnecting the electrical connector & listen for the knock to disappear. Then you'll know what cylinder is bad if the knock goes away.
 
When I've had bad rod bearings, usually when you rev it up to 2500-3000 RPM and hold it at steady RPM with the throttle is when it gets the loudest. Otherwise it'll take dropping the oil pan & bearing caps to verify what the problem is. Or put in 20W50 & drive it until one comes out the side of the block & then put in another engine.
 
Korean car. Transmissions and engines have been known to let go long before 100k miles. 10yr warranty winds up being a joke.

When they were half the price of a Toyota I could see the point. Their cars are now costing more than an American model!
 
Thanks for the comments, guys. I've already tried the filling up with 91 octane gas when my tank was half full, will try premium gas at next fill up. It is hard to record the sounds because there is no knock when engine is at idle or revved up if in the parking lot. It happens when the aircon is on and I'm gently accelerating up a ramp in first or second gear (auto transmission) or accelerating from 5 mph to 20 mph on level road. I don't know if the knock is there beyond 20 mph because of road noise and of course the engine is louder.

@bubbatime
Fortunately, my knock noise is not the rod knock you posted.

@turtle
No, I don't have a mechanical oil pressure gauge. Just the dumb oil pressure warning light. Once the engine starts, it never lights up.

I discovered something today. I'd parked the car on the street behind the condo. Tried to record the knock with my iPhone on the dash by starting the cold engine and going up the condo ramp to my parking slot on the second floor. It always knocked before when doing that as I'm coming home from work. But there's no knock today with the engine cold. So it seems there's knock only when the engine has warmed up. That's encouraging to me. Roofless, you may be right. And it may be pinging only once the engine's hot. Let's see if it goes away with next gas up with premium.
 
Update: I filled up 2 weeks ago with premium when the tank was down to half, and the knock is largely gone. Still happens but very very rarely but now softer sound quality and still only when under load with the A/C on. So I guess it's the gas quality. I've been patronizing only one gas station for the last 3 years and I changed to another station this time.

I'll be soon trying water injection into the air intake through an atomizer and see if it's also carbon deposits in the combustion chambers.
 
Originally Posted By: berniedd
Update: I filled up 2 weeks ago with premium when the tank was down to half, and the knock is largely gone. Still happens but very very rarely but now softer sound quality and still only when under load with the A/C on. So I guess it's the gas quality. I've been patronizing only one gas station for the last 3 years and I changed to another station this time.

I'll be soon trying water injection into the air intake through an atomizer and see if it's also carbon deposits in the combustion chambers.


Yeah sounds like spark knock, you probably have been putting gas in that did not have enough detergents to avoid deposits. The deposits create hot spots in the engine and effectively increase the compression of the engine leading to spark knock, stick to top tier gas moving forward and maybe try a fuel system and combustion chamber cleaner (Redline fuel system cleaner is a good one that goes a long way). Good thing you caught it when you did as spark knock can grenade an engine.
 
Originally Posted By: pezzy669
Originally Posted By: berniedd
Update: I filled up 2 weeks ago with premium when the tank was down to half, and the knock is largely gone. Still happens but very very rarely but now softer sound quality and still only when under load with the A/C on. So I guess it's the gas quality. I've been patronizing only one gas station for the last 3 years and I changed to another station this time.

I'll be soon trying water injection into the air intake through an atomizer and see if it's also carbon deposits in the combustion chambers.


Yeah sounds like spark knock, you probably have been putting gas in that did not have enough detergents to avoid deposits. The deposits create hot spots in the engine and effectively increase the compression of the engine leading to spark knock, stick to top tier gas moving forward and maybe try a fuel system and combustion chamber cleaner (Redline fuel system cleaner is a good one that goes a long way). Good thing you caught it when you did as spark knock can grenade an engine.


A bottle of techron in a tank of gas then a bottle of berryman's chemtool in the next tank. Run that out and fill up with fresh top tier gas and see what you get.

The techron is really good at getting hard carbon out and the berryman's gets varnish and the sticky stuff. This is Trav's regimen for a knocking engine. These fuel cleaners will also clean up the injectors and that can help control knock as well
 
Update, guys. I've been using premium gas the past 16 months to avoid the knock, and results have been pretty satisfying. Last month I put in a bottle of Concentrated Techron to my 3/4 full tank and ran it almost dry. Then I filled up 1/4 tank with regular gas, and the knock came back. So I filled her up with premium and the knock disappeared.

Now I want to try water injection with an atomizer into the hose after the air filter. Anyone know how much water I should try to get a reasonable chance of getting carbon out of the combustion chambers? Engine is a 4 cylinder 2.0 liter inline.
 
Have you tried driving the car like you hate it? We bought a 90 Chevy truck for our shop and it pinged like crazy under moderate acceleration land even some under light accel). We just kept driving it and I always drive it pretty hard because it's pooch. Then one day I noticed it didn't ping any more. No changes in fuel or timing either. I figured it was carboned up pistons from lots of short trip, light load driving.
 
If your problem is the same as ours, it will not resolve itself immediately. Ours cured itself over the course of a year or more - but we don't drive it every day.

Not sure if there was a suggestion to use Chevron w/ Techron, but it's pretty good with deposits.
 
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