Rumbling/Vibration noise around 3000 rpm

[BrokenSword]

Okay so this just happened recently. Every time I reach around 3000 rpm, there's a rumbling/vibration noise and it feels like its somewhere around the floor board area. It's a lot more noticeable on 1st gear, but every gear pass that it seems to lighten up. Not sure if its the exhaust, I tightened up the muffler part yesterday, it still rumbles.

[mechanicalmoron]

I'd guess your engine is not running as smoothly as it was.

[s14wayzz]

I'd guess your engine is not running as smoothly as it was.

i'd agree with that

[Hijacker]

Vibration in a specific rpm band makes me think something isn't balanced right. Inspect all the rotating bits you can see for damage, missing weights, worn bearings, etc.

[BrokenSword]

You think possibly a messed up flex downpipe might be a factor?

[daemonyk]

You think possibly a messed up flex downpipe might be a factor?

no...

Usually if it's speed dependent regardless of gear or rpm, the imbalance is typically on the rotating parts after the transmission (final drive) - if it's RPM dependent regardless of gear / speed, then it's typically on the rotating mass in or on the engine. If it's something that doesn't spin and is just loose (like exhaust pipe), it wouldn't do it only at specific speeds / rpm's, and would probably do it all sorts of random times.

Being that it feels like it's right under your floor, and varies with RPM, I'd guess you may have an out of balance FW or clutch in some way, pilot bushing could be worn out, something like that

[BrokenSword]

Being that it feels like it's right under your floor, and varies with RPM, I'd guess you may have an out of balance FW or clutch in some way, pilot bushing could be worn out, something like that

I'm really hoping its not any of those. just got my SR swap last year in Janurary and I know the previous owner replaced all those. if it is that, im guessing it's best if I just stop driving it until I get it checked out first, before something else worse happens. sucks that this is also my daily driver as well.

[daemonyk]

Being that it feels like it's right under your floor, and varies with RPM, I'd guess you may have an out of balance FW or clutch in some way, pilot bushing could be worn out, something like that

I'm really hoping its not any of those. just got my SR swap last year in Janurary and I know the previous owner replaced all those. if it is that, im guessing it's best if I just stop driving it until I get it checked out first, before something else worse happens. sucks that this is also my daily driver as well.

So wait, lemme see if I got this right. You got it in Jan of last year, so Jan 2012, yes? And those parts were replaced by the previous owner before you ever even had that engine? How long before? And how do you know for certain they were replaced, what exactly was relpaced, and what they were replaced with? Who installed the parts?

Not tryin to be a punk about it but it's one thing if the guy was a friend and he had everything replaced with oem or Name Brand parts by a good shop right before you got the engine and you saw it for yourself - and completely different if you didnt know the guy at all, and he replaced them when HE got the swap 2-3 years before THAT, and only replaced the clutch, and used a SplodeMaster ebay clutch, and did it himself and did less than perfect - if he actually did them at all.

Of course, in addition to considering those things, maybe see if you can have a local car-savvy person drive it and see what they think? There's all kinds of things that can cause shimmy problems. But most of them spin or rotate

As far as the stopping of the driving of the car, someone else would probably know better than I.

[BrokenSword]

So wait, lemme see if I got this right. You got it in Jan of last year, so Jan 2012, yes? And those parts were replaced by the previous owner before you ever even had that engine? How long before? And how do you know for certain they were replaced, what exactly was relpaced, and what they were replaced with? Who installed the parts?

Not tryin to be a punk about it but it's one thing if the guy was a friend and he had everything replaced with oem or Name Brand parts by a good shop right before you got the engine and you saw it for yourself - and completely different if you didnt know the guy at all, and he replaced them when HE got the swap 2-3 years before THAT, and only replaced the clutch, and used a SplodeMaster ebay clutch, and did it himself and did less than perfect - if he actually did them at all.

Of course, in addition to considering those things, maybe see if you can have a local car-savvy person drive it and see what they think? There's all kinds of things that can cause shimmy problems. But most of them spin or rotate

As far as the stopping of the driving of the car, someone else would probably know better than I.

previous owner was my brother. I know he replaced all the seals and what not, all nissan oem. water pump, new thicker head gasket. running s15 turbo. it's got an ACT clutch. I know he had it around 08 and did everything beginning of 09. so most of the parts on it is fairly good.

[daemonyk]

Fair enough. And he definitely did the pilot bushing, too? Cos unfortunately alot of people skip that for various reasons.

At the same time I don't really feel its a fair assessment to say "yeah they were installed 4+ years ago and driven on since then, im sure they're still fine now", cos they may not be. A really spirited driver can nuke a clutch in a week with a little effort. 4 years is plenty of time to wear out drivetrain parts if they're work'd hard over time, esp clutch parts cos those are wear parts. And this doesn't sound like an engine that was built to go slow and delicate.

I hope I'm wrong But that's what the symptoms are hinting at to me.

[BrokenSword]

Fair enough. And he definitely did the pilot bushing, too? Cos unfortunately alot of people skip that for various reasons.

At the same time I don't really feel its a fair assessment to say "yeah they were installed 4+ years ago and driven on since then, im sure they're still fine now", cos they may not be. A really spirited driver can nuke a clutch in a week with a little effort. 4 years is plenty of time to wear out drivetrain parts if they're work'd hard over time, esp clutch parts cos those are wear parts. And this doesn't sound like an engine that was built to go slow and delicate.

I hope I'm wrong But that's what the symptoms are hinting at to me.

true on that. I'm not trying to seem like a butt about all this. since I didn't put this engine together myself, kinda hard figuring out where to start since I don't know what's been touched for sure.

[daemonyk]

Oh, no worries, it's a block we all hit sometimes. Not-knowing an engine is exactly why it's advised to inspect it thoroughly before installing it, maybe even refresh a few things on it. I'm going through the same song n dance with my RB. Unfortunately there's nothing to be done about it except jump right in and get to it. Re-do-ing buncha things sounds like a PITA, but at least when you're done you'll know the car a whole lot better cos you're the one that did it.

I still suggest you have someone with car skillz ride with you and see what they think.

[mechanicalmoron]

You probly wouldn't feel it by 3k (that's more like where it vanishes) but there are various sensors, from coolant temp to throttle position, that will have an effect on timing advance, and can make your motor run like crap. They can also do it intermittantly, like only when it's warm or cold or damp or something.

Check it for codes. Also, pop the hood, and see if the motor is shaking when it idles. You can twist the throttle by hand and watch/feel the engine to see exactly what's moving, and how it's moving.

The motor should sit pretty still/solid (if everything's perfect) when it's idling, and should twist on it's mounts when you open the throttle, but should still stay pretty still once you let the speed level off.

If you do this and hear the exhaust rattling, well, it's your exhaust. But it sure doesn't sound like the exhaust.