We bought a used 2005 Subaru Outback last year and had our trusty Subaru mechanic check it out. He changed the transmission fluid and said car was a gem. We spent the winter away from our home in midcoast Maine but not away from winter. Every time temperature got below 30 our car ‘bucks’ while driving. When transmission shifts from second to third it thumps. Another mechanic looked at at this issue, even conferred with our Subaru mechanic back home, and they decided a complete transmission fluid flush was the answer. We still had this issue after that transmission flush but it ended when spring finally came. When the temps get above freezing the thumping stops. Back home this fall we took it into our local Subaru mechanic with, you guessed it, the same problem. They checked it all out and said it was a fuel filter issue. The transmission is fine. Well, driving in below freezing temps and car is thumping again. What seems to work is to let it warm up and then it does not thump when automatic transmission shifts. We are out about $700 after all these previous ‘fixes’ so would like to get some other advice as to what is going on with our car .
Is it a hard shift that thunks when it goes into gear? When you warm up the engine just sitting in park does it thunk? Or do you have t drive it to get it warm? Does the temp guage have to be at a certain point to stop the noise?
The thumping does not happen when car is in park and we are warming up the engine. As it was 17F this morning I let the car warm up for about 15 minutes. The temperature gauge after 15 min warm up was beyond C and about halfway to the midpoint on the gauge. I drove it up a slight incline and did not experience the thump in shifting. So it seems that gauge has to be at least to that point for thumping not to happen. If we drive the car immediately on a cold start the ‘thump’ will happen when transmission is shifting into gear.
Here is a description of the third gear operation from the manual:
6. 3rd GEAR
When the 3rd gear is selected, the low clutch and the high clutch are engaged. The engaged high
clutch rotates through its drum the front planetary carrier, and rotation of the carrier is transmitted
to the rear internal gear through the engaged low clutch. In this power flow configuration, the rear
sun gear and the rear internal gear rotate at the same speed since the rear pinion gears are solid
on their axes and the whole planetary gear train rotates as a unit at the same speed as its sun gear.
As a result, the input shaft and the reduction drive shaft rotate at the same speed.
In the 3rd gear, the one-way clutch is freewheeling because the low clutch is rotating clockwise.
Since the drive power is transmitted without passing through the one-way clutch, the backward driving
force from the wheels is transmitted through the reduction drive shaft to the input shaft; this
makes the engine braking effect available.
The trouble may be due to the operation of the high clutch which is used instead of just using the low clutch for the first two gears. Since warming things up seems to make a difference, the problem may be due to some valve sticking. There is a product on the market called Trans-X that some folks have used with success when having shifting issues like this. At least it won’t cost a lot to try it. It may take a little time to work once it is put in.
Thanks Cougar We will give this a try!
Is this an automatic transmission? Is it happening going from reverse to drive? Or between gears? Because every Subaru since ~ 2000 my family has had till the CVTs came out tend to thump into drive from reverse when cold. Dealers and repair shops have said this is normal for the Subaru transmissions, and happened even with new (less than 1yr old) cars. No transmission issues at all except for the hard (sometimes very hard) shift from reverse to drive.
Why is there a 100 word explanation in the manual for 3rd gear? Is there also the same detailed info for 2nd gear? Or 4th gear? In a nutshell, what is subby trying to say about 3rd gear? That it may make noise?
Well, it is a ‘thump’ that shakes the car. Will a stuck valve do that? Looking into Transmission X fix with my mechanic. It is an automatic transmission
If the thump only occurs when the car shifts gears then it sounds pretty typical for a pre-CVT Subaru transmission. My automatic 1999 outback gives me a kick in the seat when it shifts. Transmission has been overhauled once around 60k miles and will probably need it again when it gets too bad or it starts to hesitate too much when shifting. Many people have issues where they have to sit & wait for the car to shift, especially from reverse to drive. I recall the shop saying it was a chronic thing with that generation, but I forget exactly what the explanation was. I think it was something about an o-ring that was known to shrink or stick such that the normal fluid pressure was not building up properly and managing the shift smoothly.
My issue was like BigAl’s post here at 1:01pm 2-27-2013:
ccatx- Thanks for the link. I reviewed all the comments. Seems to be a problem with pre-CVT Subaru transmissions. Your comment ‘kick in the seat’ when it shifts describes what we experience. This winter I have been letting the car idle for 10 min or so and warm up with our single digit days. This seems to ‘cure’ the kick in the seat.
The transmission internal seals are 11 years old so the possibility of an internal pressure problem which can lead to balky or hard shifts is possible. Hopefully this is not the case.
What about the possibility of a bad pitching stopper? It’s easy to check and inexpensive to fix. They’ve been known to fail and this can lead to a thump when shifting into gear or while the trans is shifting gears.
This is what the little critter looks like. (varies by model and year)