Subie Vibration

[gathermewool]

What:

Higher frequency vibration that shakes the car. In my mind, a low frequency vibration would be if a cylinder were missing or if the car were running roughly. This is not that.

When:

1. Fully stopped, regardless of whether my foot is on the brake or not.

2. Acceleration at greater than granny-style or accelerating uphill between 2-3k RPM. I've noticed this both in second and third gear.

Recent Maintenance:

1. Both CV shafts replaced with new within the last 3 months. Replaced the driver-side CV shaft again last month thinking that was the issue. No change.

2 Plugs changed out from NGK plat to NGK Cu along with new wires 6 months before the vibration started occuring. I pulled them last week and they looked perfect, no fouling and the gap was spot on at .04

3. Fuel pump replaced in the freezing freaking cold last night in my parking lot. The strainer is new and the filter was replaced as well. The death rattle coming from the pump is gone, but the vibration remains.

4. Transmission fluid drained and filled a few times in the past 40k. The latest was with 6 qts of Amsoil ATF 1.5 years ago. Fluid looks great, and is at proper level.

What I've noticed:

1. Transmission mount and passenger side motor mount both look good - probably not the original. The driver-side is old-looking and dirty, but seems sound - no cracks or bulging, and it feels as pliable as the newer looking passenger-side mount.

2. The vibration issue isn't consistent. It SEEMS that it's MUCH better after driving around for a while, when the transmission has come up to temp. My commute is 5 miles to work and, while the coolant just gets up to temp, I'm guessing the transmission hasn't. The bad when I leave for work and slightly better, but still very noticeable when i get to work. When I drive around town running errands it seems to subside even more.

3. My freaking front right caliper is leaking fluid past the piston Life time warranty on that one, though!

What I've found on the interwebs:

1. Most people who had something similar had their mounts, plugs, wires and coil pack replaced, none of which fixed the issue.

2. No one come back when they've either given up or solved the problem! Every one asks for a solution, and while knowing what does NOT work is good, knowing how you fixed it back n 2007 is probably better.

I promise to update this if I figure out the issue.

 

[FL_Rob]

Exhaust system loose point maybe,it dosent take much to create a vibration.

 

[gathermewool]

Originally Posted By: FL_Rob
Exhaust system loose point maybe,it dosent take much to create a vibration.


Could you elaborate, please?

 

[WagonBoss]

A little more troubleshooting -
Does it vibrate whether you are in gear or not?

When were accessory belts replaced? You've checked for proper tension?

Did you check pulleys for play?

Exhaust manifolds tight?

Body mount donuts serviceable?

Those are the things I can think of to check.

 

[gathermewool]

The vibration is mostly while in gear. The vibration is still there, but only at maybe 10% of what it is in gear. One weird thing I noticed while gassing up today is that the vibration didn't go away when I put it in P until I let off the brake, allowing the car to slightly roll forward - the gas stations slab must not have been perfectly level. I repeated the process from drive back to park and the vibration remained until I let off the brake.

I haven't had a chance to pull off the A/C belt, but both were replaced at the same time 30k ago, and the one I did pull off - the ps pump/Alternator belt - looked perfect. I'll check tension tomorrow.

There don't seem to be any exhaust leaks, but I'll put a torque wrench to the mani when I get the chance.

Body mount donuts?

Thanks for the help!

I'll check the main and A/C tensioner pulley tomorrow

 

[FL_Rob]

Try this, when everything's cool enough to touch,shimmy under there,grab the exhaust system and give it a real good shake test .The grommets on exhaust hangers is where I would focus on.Something is setting up a frequency vibration.

 

[Ed_T]

If you haven't eliminated engine, stuck injector?

 

[IndyIan]

Maybe exhaust manifold and cat heat shields? I've had them buzzing at particular rpms.

 

[gathermewool]

It doesn't feel like a vibration being caused by a heat shield. For reference, the fuel pump I just replaced had a vibration similar in sound to a loose heat shield. The vibration transmitted up the hanger, to the fuel tank to the frame to my foot. I could hear and feel the vibration.

This feels much more substantial, and feels like it would be related to either the motor or transmission. I can see the engine shake a bit when it's at its worst - I parked on a steep hill, blocked the tires and left it in D while I checked under the hood. Unfortunately, since I drove a bit between work and finally getting it up on a lift, there wasn't much noticeable yesterday.

What are the symptoms of a stuck injector? I did have a cold-engine rapid ticking on deceleration that seemed to have been solved a quarter of a tank treated with the larger bottle of Chevron Techron, for what ever that's worth.

Another thing. This past weekend I drove 2 hrs down to NY this past weekend I made a point to drive a little more aggressively as a sort of Italian tune up. In fourth gear, I was driving maybe 70-80 the entire time with a moderate foot when accelerating. No vibration, shuddering or anything was noticed; the car ran smoothly, and power was good. However, when I got there, the vibration was still present, and accelerating from a stop still produced the 2-3k shudder/vibration.

 

[mechtech2]

Was this vibration always there?
Did it's onset occur suddenly, or build up slowly?

A small engine often vibrates at idle. It will be worse in gear, because it is loaded.
Heat shields on the whole exhaust system can vibrate and resonate - wiggle things and check it out.

 

[gathermewool]

The vibration at around 2k has been there, but has gotten worse. The vibration, shimmy, whatever it is while stopped in gear and accelerating between 2-3k RPM seems to have started after replacing the ball joints and front CV shafts. The left CV shaft was replaced a month after the right. The vibration started soon after. This is why I replaced the new left shaft with another new shaft with zero change. I changed the CV shaft because the vibration began soon after, and a few subie guys claimed replacement shafts were usually responsible for vibration issues, even while stopped.

I didn't understand how a CV shaft could cause such vibration while stopped, but the replacement was free under warranty, and I wanted to rule it out. If what I was told is true, it could also be the right CV shaft, but I still don't believe this is the cause.

I'll check all exhaust hangers and connections again, but I really don't think that's the cause, either. Nothing has been done to the exhaust, and the onset of the issue was pretty sudden, not slowly over time. the buddy didn't notice anything unusual while under the car, either, though the car was warmed and not shaking like it usually does at the time.

 

[dhise]

Are these aftermarket axles or oem? It seems there are more than a few people reporting vibrations after axle replacements and there are a lot poor quality subaru axles out there. This is an older post, but describes the axle problem well:


http://www.ultimatesubaru.org/forum/showthread.php?t=2489&highlight=vibration

 

[gathermewool]

Thank for finding that for me. That's the thread that convinced me to replace the brand new GSP axle. What're the chances that two axles could be duds? While it happened just after replacing the left axle, IIRC, maybe the right axle is to blame?

 

[FL_Rob]

Wow, so there's a dampener that goes bad? wonder if it eventually happens in all fwd or awd cars or anything w/ cv shafts?

 

[gathermewool]

Just got back from the shop - leaky caliper is good to go!

Running on the the lift I checked around again for anything unusual. I manhandled the exhaust; nothing. I put my ear to the screw driver and the screw driver to each injector; all sounds the same, normal. I did the same on both exhaust manifolds; I hear piston slap on either 1 or 3 cylinder, but nothing unusual. The only thig that was unusual was when I pulled off each plug wire from the coil pack. Each arced to the plug wire from inside the coil; normal in my mind. Number 4 coil seemed to arc from inside the coil, and also from the casing. I checke more closely and noticed a scratch where I thought I saw the arc, but it didn't widen when I put pressure on that part of the coil pack (with the car off, of course.)

By the time I left the car wasn't vibrating badly, but still did upon acceleration. I paid particular attention to when exactly it was vibrating when I left the shop today. Going up the hill at the exit it vibrated/shook pretty badly in second gear from 2-3k. The severity of the the vibration/shake was halved in 3rd gear, and was non-existent in 4th. My car lets you give it a good amount of load before it'll down shift to 3rd from 4th, but even with a lot of load there was nothing unusual.

I want to replaced the passenger-side shaft, but I'm afraid they'll ban me from the store, since this will be my third replacement.

 

[FL_Rob]

At night go do it now in the dark,run the car with the hood up a little see if you can spot arc tracing from that number 4 coil pack, opinions ?

 

[gathermewool]

I'm heading out to work now. I'll pop the hood and see what I see before driving off.

 

[deeter16317]

Could you have damaged, or not gotten one of the wires fully seated, when you pulled them off?

 

[gathermewool]

I pulled the wires to check the plug gaps a few weeks ago. I made sure to apply pressure until they seated with a pop. The coil pack connection is pretty simple, too.

Also, no arcing at the coil when I first started the car this morning. Lacking a spray bottle, I even went so far as to spit on it - twice, since missed the scratch area on the first try. haha.

One more thing: When I removed both belts last night I noticed the alternator made a slight squeaking noise when I spun the pulley. The shaft seemed a little bent, making the pulley slightly wobble. Something to worry about now or later?

 

[deeter16317]

Originally Posted By: gathermewool
The vibration at around 2k has been there, but has gotten worse. The vibration, shimmy, whatever it is while stopped in gear and accelerating between 2-3k RPM seems to have started after replacing the ball joints and front CV shafts. The left CV shaft was replaced a month after the right. The vibration started soon after. This is why I replaced the new left shaft with another new shaft with zero change. I changed the CV shaft because the vibration began soon after, and a few subie guys claimed replacement shafts were usually responsible for vibration issues, even while stopped.

I didn't understand how a CV shaft could cause such vibration while stopped, but the replacement was free under warranty, and I wanted to rule it out. If what I was told is true, it could also be the right CV shaft, but I still don't believe this is the cause.



I missed this earlier...took me to the last post.

Your problem is most likely the axleshafts...I have an Outback, and it started vibrating soon after replacing the shafts. It seems the aftermarket shafts (ALL OF THEM) are slightly longer than OE (for whatever reason) and that causes the normal minor shaking in the engine to be transmitted to the rest of the car.

If you want it gone, replace the axleshafts with OE Subaru shafts. That will most likely solve your issue.