Thread: rattle between 2500 and 5000 rpm - please help!

I drove my car warm in 20 minutes. I've put a 2.5" SS Autochrome under the car about 400 miles ago. When I drove the car with the Autochrome, I decided to shift at 5000 rpm or so because what I could notice was going on under the hood, wasn't really what it should be. Besides the great SR20 sound, it started to vibrate a lot more then usual and my rear motormount is totally gone also.

I took the car for several fun drives, again with the warm up in mind and going to 5500, ok, 6000, ok I decided tonight it was time to test up to 7000 or so. I decided to shift on 7000, not just for the vibrations that slowly faded away but also by not lead footing the car but just see where the sensible shifting point is, one will notice it takes a little while for a 120k miles car to settle.

So I was thinking I'm doing ok, guessing that wiht the WAI filter and header and advanced ignition I should be making 160HP the least.

However, at the third pull to 7000 rpm, I developed a noise, I heard a RRRRR.

I slowed down to 60mph and kept the speed steady. It didn't make a noise which shouldnt be there (not to mention the interrior and left power window).

So I gently opened throttle, sound came back. I pulled over, open the hood, car idles great, it all sounds ok besides a little upper chain guide rattling/ rinkle.

When I played with the throttle, that RRRRRR sound was back again and didn't want to go away.

I hooked up Datascan, no faults, it is also not a knock code, but the sound is like it is comming from cylinder 3, I'm not really sure about this.

So I took my screwdriver and put my ear on it and listened on all cylinders. On cylinder 1 the njiiiiihh sound of the chain is there and no problems found. Cylinder 1 sounded ok. Cylinder 2 also. Cylinder 3 has the sound. On cylinder 4 the sound became less.

What puzzles my is that I put the end of the screwdriver on the valve cover, that is where the sound seems to be comming from. But it idles fine and with Datascan I noticed the sound develops on 2500 and dissapears on 5000.

What could this be then?

Edit: A friend of mine listened to it and told me it sounded like this: http://www.youtube.com/watch?v=1BTBrJb3P9o&feature=related which is not a joke, it does. I mean the first seconds and the chopping sound of course.

bad hydraulic lifter... can you get a video...

do not rev it any more. pop the valve cover and check internals. does it sound like a rod knock in cylinder 3?

I could try this but my Nokia seems only have this USB connection for service personel. I was able to pull 1 vid and then no nothing, not even backup contacts. I will try to find someone who can but those people are not in to hooking up their phone with the pc




I'm able to pop the valve cover, but that is about it. It would be visible then? I never lost the timing nor I have a torque wrench that is certified.

First thing I was thinking is rod knock but somebody told me that would not make the car idle fine.

I don't really know what to do, because I'm not even sure it is the internals that went.

I forgot to mention with listening with the screwdriver, I put the screwdriver lower in the blok and the sound was very faint.

So you might be just right, but I lack the understanding what it might be and what to look for exactly.

premature signs of a rod knock will not affect your idle. you will hear the knock at certain rpm. the worse the knock becomes. the more you will hear while idling. a rod bearing is not visible. you will have to pull your oil pans and check each rod.

what is the mileage on the motor?

I agree with what you tell me, that premature signs of rod knock won't affect idle and I also can imagine it goes away at 5000 rpm. It are really hard points where it becomes audible and goes.

It also sounds like it is comming from under the valve cover and after listening to several rod knock posts (with the required film) and this one is so loud, on the other hand I can't really know how the films sounded in real.

I can pull the oil pan tomororow, not afraid to remove the rest, but then I will find just the lower shells right? (We call those lagerschalen, bearing-shell) Those could have burns and the like? I better start looking for the numbers I will see there?

But the rod's, big end and small end (forgive my bad English) then I have to take the crankthing (that thing with the counterweights) out right?

That is kinda too much for me since I'm told taking out that thing without pulling the whole engine (no tools yet, no room either) is better then just taking out the crank thing? Is this true? I also don't really see how I can hookup all the pistons at once again and putting that thing back, on my own and if I would, it would be my first time.

To sum it all up, I'm wondering if it could be the head or the little or big bearings (probably big, right?)

Does it make sense, if this is rod knock, I only really can hear it in the valve cover?

So, you ask me to make a little film and also to take of the pan, sounds doable. But then?

p.s. 122k miles and never before made such power, it was slow as hell when I bought the car and all suspicion goes to the extra power of the SS Autochrome, however, I assumed that would be no problem at all and also realized I took a risk with it.

YouTube - SR20 No.3 Rod Knock

remove your valve cover and make sure there is nothing loose or damage. i doubt it will be a bad hydraulic lifter because you will hear it at idle. make a video and see if others here can comfirm its a spun bearing. sr20 motor are prone to damaging cylinder 3 rod bearing. in order to get to the rod bearings you will have to remove both lower and upper oil pans. if you can do a full rebuild do it. if not then swapping the rob bearings for now is ok if the crank is not damage and motor has good compression.

Hmm. My first step is finding out where the SR20VE is for sale atm.