My L03 has a vibration that starts at 2200 rpm, and disappears again at anything over 2350.

I'm sure it's engine-related. It does it when the car is sitting still.

I've unhooked the serpentine belt to isolate the accessories, and it still does it, so I'm confident it's not alternator, water pump, smog pump, etc.

It started doing this two years ago. Around the time it started, I replaced the timing chain and put the exhaust listed in my sig on the car.

Over the past two years, the vibration has remained constant, getting neither better or worse.

This thing has puzzled me for a long time. It's clearly from the pressure plate forward, as it vibrates standing still, in neutral. I don't think it's anything internal in the engine, though. First, it only starts at 2200, and goes away by 2350. I think it'd get progressively worse as you rev higher if it was internal. This doesn't. It also hasn't gotten any worse over the past two years, again, something I think it would've done if there was something wrong internally. The oil pressure is good, and the oil comes out clean.

I've got three main suspects. The first was the harmonic balancer. We'd taken it off when we replaced the timing chain. I've been thinking if it was bad, it'd cause this kind of vibration. I replaced it with a new one the other day, however, and the vibration is still there.

The second thing I suspected was the pressure plate throwing a spring. This seems less likely some two years later, though, as I'd think a problem with the pressure plate would have gotten worse (at least), if not failed entirely.

The third suspect is some kind of an exhaust harmonic. I've never heard of anything like this, but I did swap the exhaust out around the time this vibration started.

Has anyone experienced anything like this, or have any ideas on how I might track this down?

 

I once had an issue like that, and it ended up being a bad motor mount. Check the rubber on your motor mounts, and make sure they're in good shape, and if not, they run about $25 each, but they can be a pain to remove with the coil springs in place. Hopefully it's something simple like that

 

Thanks, I hadn't thought of that. I'l check it out.

 

It took me a while to figure it out as well, and it had me STUMPED, because the car showed no symptoms other than that vibration.

 

could be a motor mount, could be your tranny, could be your harmonic balancer. i doubt it is your engine physically.
once upon a time i had a problem where I would rev the car, and exactly at 3k rpms i would get a nasty rattle. turns out it was just the exhaust flange hitting the frame. Funny how the harmonics worked out on that.

 

Can't be the harmonic balancer; i just replaced it.

Can't be the tranny, it vibrates sitting still, with the trans in neutral.

I've checked the exhaust, there's nowhere it comes near touching anything

 

1. you may not have the harmonic balancer seated properly

2. i hate to break it to you, but even in neutral the transmission is still moving gears.

3. Look again around the collectors, and the master cylinder areas for anything touching.

 

If the harmonic balancer was not seated properly, it would probably have a visible wobble. Neither the old or the new harmonic balancer wobbled. Also, if the vibration was caused by an improperly seated harmonic balancer, it would probably be constant and get worse as the rpms increase; this doesn't.

I carefully inspected the crankshaft and the old harmonic balancer, and watched for anything irregular as I installed the new one. There was nothing. The vibration is the same with the new harmonic balancer as it was with the old one. Harmonic balancer as a cause of the vibration is ruled out.

I hate to break it to you, but my car has a MANUAL transmission. When the car is in neutral, the only thing in the transmission that can possibly be turning is the input shaft; and then, that's only a possibility. If the bellhousing is properly aligned, the input shaft probably won't turn at all. When the car is in gear with the clutch disengaged, NOTHING in the transmission is turning. Since the vibration is the same when the car is in neutral as it is when it's in gear with the clutch pushed in, either the transmission and bellhousing are properly aligned, and therefore the input shaft is not turning in neutral, or the vibration has nothing to do with the transmission. Either way, Transmission as a cause of the vibration is ruled out.

Dude, I said I checked. I've checked. Carefully. More than once. Besides, this is a rhythmic, modulating vibration, not a "nasty rattle".

I don't understand why you want to argue. You've never seen the car, you've never heard or felt the vibration. I appreciate your input, but, your suggestions have already been considered, tested, and ruled out..

 

lol i love how a loser like you, who is so desperate for help is such a *****. I am going to laugh when you have to take that engine out because you have crappy bearings. Have fun with that

 

yeah, all those things spinning around in the transmission while it's in neutral will definitely make those bearings "crappy"

 

If you ever find out what it is please post it
I have the same kind of thing for almost 2 years now, I have removed the tranny and started the engine. The sound was still there.
After doing the T5 swap the sound is exactly the same as before lol..

Anyway I was thinking of pulling the y pipe and drive it around but its so
loud..I even have taken it to a local speed shop where a few guys said
its doesnt seem like the engine and went for a ride with me and couldnt put there finger on it for sure they suggested it might be my driveshaft ujoints or something in the exhaust, but to me it is sounds like something spinning and hitting something.
The sound is the same with the flexplate or flywheel so I can eliminate that.

I havent had the time to fully investigate other things since I dont have
a good place to work now and I dont have that much experience either.

goodluck
Dave

 

I think it's exhaust related. I would suggest biting the bullet and replacing the motor mounts if they are the originals anyway. They are ~20 year old rubber if they are original. (be ready to buy a couple of long wrenches to bend up). Other causes that could be a quick check are a couple of bolts on the clutch cover (pressure plate) or bell housing could be loose. These can cause vibration at certain RPM. Most likely it will be vibrating humm caused by exhaust sections of pipe moving like a plucked guitar string at certain rpm. If you can feel it (like in the dash) more than hear it, you can disconnect the pipes and see if it goes away.

 

Help! I have this same issue. I even tried new motor and Trans mount.

 

i just found my problem was a few loose tranny bolts to the block cured the problem instant..good luck!