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Slight knocking sound (possible bad rod bearings)

26K views 9 replies 7 participants last post by  pete c 
#1 ·
Hey guys, I know I haven't really posted here, but I think I may have a serious problem on my hands, I have a 2007 sonata 2.4L with 93k miles that has a knocking sounds coming from the bottom of the engine. It seems that it is a bad rod bearing and was caused by low oil levels. I did not know that the oil was that low (3 quarts low) It started about a week ago and what I'm wondering is if anyone here has replaced the rod bearings and if so how easy is it to do? I know I'm gonna have to put it on jack stands and drop the oil pan. Does anyone have any other suggestions?

By the way, Here is a video I found which I do believe is from another member on these forums and it sounds similiar to my car. Here's the link

I found a set of rod bearings on Rock Auto for around $30. I've been looking around on the internet and for a 4 cylinder engine it would seem that its fairly easy (but also a pain in the a$$ at the same time) to replace them. Any Thoughts?

Thanks
 
#2 ·
Also another thing I forgot to mention. Last week when it started. I stopped to get gas and it started happening. Shortly after that, the Check Engine light came on. I stopped in at AutoZone and they pulled a P0011 code which is timing over advance. A few days later. My wife takes my singer (I'm in a band) to a music shop and they stop to get gas, at which that point the CEL turns off but I still have a knocking sound. I talked to my father in law and he said it could just have been bad gas causing the engine to ping. I added some seafoam to the gas tank and also did an upper intake seafoam treatment (induce into vacuum line) which did help some but knock was still there. Its very little at idle. and if I rev up the engine fast it doesn't do it but it does knock when the rpm's go down. If I hold it steady around 2000 rpm its continuous.
 
#3 ·
IIRC, replacing rod bearings cannot be done with only jack stands; you have to remove and (mostly) disassemble the engine. If you drop the oil pan you only have access to the bottom half of the bearings. I don't know how you could get access to the upper half of the bearings without removing the heads and crankshaft. At least I've never seen rod bearings replaced without pulling the motor but then again I don't play a mechanic on TV. :grin:
 
#4 ·
IIRC, replacing rod bearings cannot be done with only jack stands; you have to remove and (mostly) disassemble the engine. If you drop the oil pan you only have access to the bottom half of the bearings. I don't know how you could get access to the upper half of the bearings without removing the heads and crankshaft. At least I've never seen rod bearings replaced without pulling the motor but then again I don't play a mechanic on TV. :grin:
Back in the day people used to be able to pull out the bearings on some cars with out pulling the motor. I doubt that is the case on newer cars today plus you would want to inspect and make sure everythign looks good. Either fix it right or drive it til she blows. I don't think used NF 4 cyl motor costs alot these days?
 
#5 ·
You be putting engine in it.

Find a clean used engine, or pony up for a Hyundai re-man short block.
 
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#8 ·
A late reply, but 9 times out of 10, when the p0011code comes up its usually from a dirty or clogged ocv (oil control valve) which could have been contributing to the engine noise as well. Theres a sticky I believe somewhere on how to remove and replace the ocv, but blowing compressed air through the filter screens on the ocv can sometimes free up dirt that's caught inside.
 
#9 ·
OCV filter screen on the THETA is in the top of the block,, hole in deck in which the filter is placed, then head gasket, then head bolted down.. good luck cleaning that screen..
 
#10 ·
You can change rod bearing in an engine. I did it to a Taurus SHO I had. The problem is, you do this as preventative maintenance. Once the bearings are scorn to the point of knocking, the crankshaft bearing surface is damaged as well. The only fix is to pull the crankshaft and have it turned/replaced.

If you have the skills/tools/time/inclination to take on a full rebuild, it can be done. Not to sound like a douche, but the fact that you thought you could just replace bearings to get rid of a knock tells me you likely do not have have this skill. I learned this a loooooong time ago with a toyota supra that developed a knock after running it hot for a short period. That was an expensive, lengthy learning experience. I actually did rebuild the engine....twice. The first time, I learned what happens when you put a bearing in with the oil holes blocked. Wont do that again!
 
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