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Old 06-30-2008, 01:17 PM   #1
MaddMax
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Member#: 9264
Join Date: Aug 2001
Location: Kansas City
Vehicle:
2012 WRX 5dr
Ice Silver

Default Is the 2.5 DOHC Phase I with a 4EAT just rough?

My wife has owned her 98 LGT wagon since 2000 and she loves it. The car currently has 107K miles and it's basically been flawless except for a couple very slight valve cover leaks and rear pinion seal leak, vibrating heat shields (I cut them off when they get noisy) and an AWD bind issue that has plagued the car since a month after we bought it. I maintain the car and have done the tranny fluid, diff fluids, fuel filters, plugs, wires, coil pack, struts, new half-shaft, etc. plus we've had the timing belt, water pump, and oil pump seal done. Since day one of owning the car, the motor just isn't that smooth and is rather noisy. The noise I'm sure is mostly a factor of heads and manifolds within 8" of the road, but still, it's not a sexy sound at all with the windows down. I've listened to other Outbacks/GTs and they seem to emit the same wheezy clamore of noise. The motor just feels grainy and the initial throttle input is slightly delayed when you press the pedal (throttle cable slack is good). At a stop with the car in gear, there is some decent vibration. This weekend, I messed around with the throttle position sensor to raise the idle rpm a bit, but that didn't seem to help too much plus I think the ECU would eventually compensate and dial the rpms back to spec over time (I know Nissans do this). I've checked engine vacuum and it's fine. All the vacuum lines are good. PCV valve is fine. I've checked the IAC system for carbon build up and it was clean.

When putting the car gear and the car is cold, I sometimes (70% of the time) hear a chassis clunk which makes me think a tranny or motor mount is bad which could be causing NVH problems, but when I was doing a half-shaft replacement this weekend, I inspected the motor/tranny mounts, I couldn't see any tears. I would think the damage would be obvious if there a problem. Do one of these mounts typically fail. The sound almost seems to come from near the upper mount that is attached to the fire wall, but it seems to look fine.

The car gets continues to get 22-23 in the city and 26-28mpg on the highway so I think tuning is fine, I guess. I just bought a new set of tires to replace the aging 5 y/o tires that ride like crap even though they have 50% tread left. Maybe that will help lower some of the NVH this car has.

Last week, I helped my sister in-law buy an 99 Impreza Outback hatchback (2.5 DOHC, Phase II) and that motor/tranny is so much smoother, quieter, and responsive. Granted the car is about 300lbs lighter, it just "feels" so much more refined. You can still wear that wheezy boxer sound, but it's not near as pronounced.

I really do like the car because it's been such a work horse, but I'm a car guy and can't but think there's something out of adjustment, broken, etc that is adding NVH to this car. We are keeping the car for another 1 to 2 years and will be buying another LGT (turbo this time). Any help or insight would be great. I guess the other possiblity is that I'm just use to driving newer and more refined cars like my 03 G35 and 07/08 rentals for work.
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Old 06-30-2008, 01:55 PM   #2
linsavy
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Join Date: Oct 2001
Location: Ontario
Vehicle:
1997 GF4-STiV3 clone

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I tried a lot of things to cure that vibration when stopped at idle while in gear. I have read a bunch of other threads on the issue as it is a pretty common issue. Nothing really worked. I tried NEW ENGINE MOUNTS, new O2 sensor, IAC, cleaning TB, new plugs and wires, flushed tranny, different oils and a new short block after the other one failed.
It was a little better with A/C on. It was much worse in winter when cold. It was fine when in park or driving.
I think it is the torque converter getting old.

The motor is a pretty noisy bugger. Lots of valve ticking and clacking. Piston slap is pretty normal too. These are mostly just the way it is and not a sign of impending doom.

Like you, it started to really bug me after I got the Lexus. The Lexus is like budda and made the Legacy seem like a tractor. I spend a bunch of time and a few $100 trying to fix the vibration, but nothing really solved it.

Last edited by linsavy; 07-02-2008 at 10:11 AM.
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Old 06-30-2008, 01:58 PM   #3
jey
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Join Date: Feb 2003
Chapter/Region: TXIC
Location: Johnson City, TX
Vehicle:
2011 Tribeca
1995 Legacy Wagon

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After 10 years I'd expect the motor/tranny mounts to be worn out. It's not always bad enough that you can see cracks/tears - but if you grab the intake manifold and can rock the engine around a bit, or if the engine is doing a lot of moving around when revved in neutral, then you just might see a lot of NVH go away with some new mounts.
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Old 06-30-2008, 03:23 PM   #4
gt_drifter
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Join Date: May 2004
Chapter/Region: NESIC
Location: maine
Vehicle:
1998 2.5 GT
spruce pearl

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^^^im with jey. ive had to replace the mounts on my bd because they were really bad, but you couldnt tell by looking at them... only by prying on them with a pry bar.
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Old 06-30-2008, 09:55 PM   #5
Minjin
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Location: Harrisburg, PA
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98 OB M/T
99 Miata

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I remember when I first went for a test drive in a 2.5RS. It was so quiet and smooth after it was started, I asked the sales lady if it was actually running as I was about to turn the starter again. No joke. The thing is, I can't be sure of what year it was (98-00?). So I don't know if it was the DOHC or SOHC model. But I remember that it was SMOOTH. My newly purchased 98 Outback with the DOHC isn't anywhere close. It has a pretty rough idle but it also has issues. We'll see what happens after a few things are fixed.
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