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Thread: Help! knocking noise only at certain rpms got louder

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2010-11-22 21:28:01
Help! knocking noise only at certain rpms got louder
My old sr20 engine went on me because of a stuck thermostat, I paid someone to replace the engine for me in February. I bought Chills old engine and the installer DID NOT TTIGHTEN the oil pickup tube all the way so it sucked air till about 3000-4500rpm, i took it all back apart and found the installers mistake and corrected it. But ever since then there has been a slight ticking/ knocking sound but only at certain rpms (most likely from lack of oil to the top of the head). 12,000 miles later to today

Today i was getting off the exit of I95 and downshifted into 3rd from 4th and the noise got instantly louder like a diesel, I made it to work (driving low rpms) and had a couple of people listen to it (I work at a bodyshop) it doesnot sound like rod knock, and it sounds like its in the head, i listened towards the ground and its quieter than if i listen up top,
I took the valve cover off all of the shims are in place, timing chain isnt too loose, tensioner springs back, nothing is visually loose, had it running with the valve cover off and cant see much because of oil spraying all over. The engine runs and sounds normal at idle till about 3000+ rpms then the noise gets louder as the rpms increase

Help would be very very appreciated, the car is in west palm. Im about to go back to driving 3000 miles a month and cant deal with too much downtime.

Any ideas?
2010-11-22 21:37:53
sounds like a rod to me, what you may be hearing is that as the rod bearing is loosing it tolerance the piston is traveling higher and slapping the head. I suggest you stop driving the car take apart the bottom end(oil pans) and look for that rod, check the crank for any damages, clean the journal if it does not have any abnormal wear and put some standard bearings in there.
2010-11-22 21:39:08
Originally Posted by Mike22487

had it running with the valve cover off and cant see much because of oil spraying all over.

Any ideas?

lol, why the hell would you do this??????

If its louder with higher rpm's then more than likely its a spun bearing. Damage was done. It doesnt take long with oil pressure problems for the bearings to fail. If its getting worse and worse then yeah its definetly a bearing.

Way you can find out is have the engine running and disconnect one injector at a time starting with the #3 (common bearing to spin because of oiling designs) and if the noise goes away with the dead cylinder, ROD KNOCK, do this to each cylinder. If the noise doesnt go away then you could have a sticking lifter. You can plug the injector back in, listen to it, unplug, listen, plug it back in and so on. Good luck.
2010-11-22 23:26:31
I did disconnect each injector separately and reved it the noise stayed, it didn't get worse or better, ill post a video for the sound later tonight (hopefully),
it is quiet at idle to 2500rpm that's when the slight sound starts (the sound I've had since february) then reving higher about 3500-4000 that's when the new sound starts, then I let off the gas at 5000rpm (it gets louder from then on), when I let off it kind of rattles a little as the engine goes back to idle
I'm going to pull the oil pans off tomorrow, will I be able to move the rods by hand or visually see anything if there is something wrong or loose?
2010-11-23 06:19:40
heres 2 videos of the engine running sorry its on a blackberry, the smoke you see is some oil burning off of the headers

you can hear that when the engine is not at 4000rpm the engine sounds normal

in this video you can hear me go from idle to 5000rpm and then back down to idle, as it comes back down it sputtered a little bit

what should i do? pull the bottom end apart and check the bearings by pulling them off?
2010-11-23 10:59:12
Ok that sounds worse than it did at the meet. For sure!
2010-11-23 20:24:31
Im going with rod knock as you let off the revs the knocking seemed to get louder
2010-11-23 21:31:55
So pull the oil pan off and replace all of the rod bearings?
2010-11-23 22:54:40
ya that right there sounds like the engine that came in my car did.. i made it less then 5 miles from where i bought it lol.. rod #2 busted a hole through both sides of the block and cracked the block in half between 2 an 3.. when we took the lower pan, crank and the head off it fell to pieces lol

time for a new motor, i wouldn't waste much money on a de unless i was really desperate.. these days its not to much more $ to just get a ve..
2010-11-24 06:46:45
I don't have the money for another de or a ve, well till february when the 1.6 will get a ve with a P11 trans
I just need this engine to get me another 30,000miles till the ve is in,
I just need a straight answer if by just replacing those rod bearings the engine will work for a while longer
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