Mechanics

LOW RPM VIBRATION

2005 Subaru Forester

Shakes or Wobbles problem
2005 Subaru Forester 4 cyl All Wheel Drive Automatic 63500 miles

I bought a brand new '05 Forester, and at about 10 or 15K miles, I noticed a very slight vibration when I came to a stop at a light (it did not seem significant enough to correct). After taking my car in for 60K service, my car started to shake/rattle very badly at low RPM when the vehicle is either stopped or moving less than 3-4 mph in any gear. It happens about 25% of the time (rest of the time, there is no noticable vibration). I took my car back to the shop, and the diagnosis was that the car needed new engine mounts and new transmission mounts. I took the car to the dealer for a 2nd opinion, and their diagnosis is that the car needs a new torque converter. Have you got any idea what the problem is?
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2005subaruForester
September 4, 2008.



Hi 2005subaruForester,

Thank you for the donation.

I would suspect it to be engine mounts. What is the idling rpm? Is your vehicle still covered by warranty?

I could not find any Technical Bulletins on faults with torque converters.

KHLow2008
Sep 5, 2008.
Thanks for the quick reply.

Idling RPM is about 750. If starting engine cold and in park, idling RPM is about 1000.

I am not under warranty. I have followed the maintenance schedule religiously. So I'm a little angry.

Is there any particular reason you suspect engine mounts?

My limited knowledge of engine mounts is that they don't break, they just wear out, so I guess there's no way I can inspect them visually to determine if there's anything wrong with them?

The mechanic at the dealership said he had trouble diagnosing the problem, so he called Subaru technical help, and they told him to rotate the torque converter 180 degrees, and apparently since the vibration was worse then, that meant the torque converter was bad.

Tiny
2005subaruForester
Sep 5, 2008.
Hi,

Since your mechanic has tested by rearranging the torque converter installed position and it has caused more vibrations, I guess we have to accept that the unit is faulty and needs to be replaced.

If engine mounts rubbers are not broken, the only thing you can see visually is if they are sagging.
You can place a jack under the engine and lift it up slightly to reduce the pressure on the mounts. If vibrations decreases, it means the mounts are weak.

KHLow2008
Sep 6, 2008.
How can I be fairly certain I've got the problem diagnosed correctly before I spend a month's salary trying to correct the problem?

I put a jack under what appeared to be a motor mount and applied very slight pressure. When I started the car the vibration was gone. Do you think I can rule out the torque converter?

Tiny
2005subaruForester
Sep 29, 2008.
Hi 2005subaruForester,

Since relieving the pressure on the engine mounts eliminates the vibration, we can safely say the the engine mounts are bad.

It just crossed my mind that while rotating the torque converter, your mechanic might have tampered with the engine mounts or engine position resulting in more pressure on them and more vibrations.

KHLow2008
Sep 30, 2008.
Thanks for the help, I had both motor mounts replaced several weeks ago and the shaking has stopped. The mechanic told me that both mounts were broken.

There is still a subtle vibration that I notice only when the engine is cold and I'm stopped (in drive). If I shift to nuetral, it goes away. I'm curious if there could be something else wrong that might have caused my motor mounts to wear out prematurely. I've had this issue for most of the time that I've owned the car.

Tiny
2005subaruForester
Dec 8, 2008.
Hi 2005subaruForester,

You replaced 2 mounts but I do not know which 2 as there are 3 mounts and 1 torque strut. The piece not replace might not have broken but it could be weak and not absorbing all the vibrations.

Th design and layout of the engine does to some extent have a subtle vibration and this should be acceptable.

KHLow2008
Dec 8, 2008.