[mdeholl]

Hi,
I'm new to this form and this is my first post. I'm a new owner of a 2003 Out Back Sedan H-6 with 137000 miles. The car runs great however when warm and traveling at a slow speeds and making a 90 degree turn there is a distinct thumping noise and the car jerks. My wife says she can see the left front tire pulsating.
Any idea what might be causing this problem? Is there a safety issue?

 

[Braap]

CV joints. Not a major safety issue, but something cheap enough to not neglect.

 

[1 Lucky Texan]

hope it's CV joints and not torque bind.

all4 tires the same model and wear?

use the FWD fuse and see if the problem goes away.

 

[Braap]

^ True that!

 

[mdeholl]

hope it's CV joints and not torque bind.

all4 tires the same model and wear?

use the FWD fuse and see if the problem goes away.

All 4 tires are new and it has a new transmission. Where is the FWD fuse?

 

[Braap]

Right in the fuse box under the hood on the driver's side. You can't miss it, it's clearly labeled "fuse box". Then look at the chart on the cover, and one says FWD and just pull that one.

 

[plain OM]

Then look at the chart on the cover, and one says FWD and just pull that one.

There is normally no fuse in the slot -- inserting a fuse disables the AWD (car becomes FWD. The test for torque bind is done by inserting a fuse in the slot. When the fuse is installed, there should be an AWD or FWD warning light on in the instrument panel.

(See attached diagram for location)

Incidentally, according to cars101.com, some 2003 H6s have VDC; I believe that in these cases, the fuse is not applicable. (The fuse does not change anything.)

it has a new transmission.

Was this installed before, or after you bought the car? Do you know why? Was the transmission replaced or rebuilt? And if replaced, was it recycled (e.g. from a scrapped car)?

A properly functioning transmission should not cause torque bind symptoms.

 

[mdeholl]

Did the FWD fuse thing and didn't have any problem. Guess I have torque bind. The previous owner is a master subaru mechanic who put in a brand new transmission. He said the transmission was new but probably been sitting on the self for some time. He recomended adding a small amount of GM Limited Slip Additive to the transmission oil. Has anyone had any experiance with this?

 

[plain OM]

Some people have reported favorable results with additives when experiencing binding in the AWD systems; many others have done a series of drains and refills of the ATF and had good results. In both cases, if a valve or solenoid is sticking due to some contaminant build up, the new fluid is often able to dissolve it, freeing the system to work properly.

However, I am not familiar with GM limited slip additives, and as I believe these are designed for particular limited slip differential designs, I have to wonder what it's role would be in an automatic. In fact, I'd be concerned.

My tendency would be to try the multiple ATF change, and if that doesn't work, then the tranny might have to be taken down.

In this regard, however, do all the instrument panel warning lights, including the check engine and AT Oil Temp lights, come on when the key is at ON but the engine is not started? Do any lights remain on after the engine is started, and especially, does the AT oil temp light remain on or flash?

That said, I'm disappointed that the mechanic doesn't seem to be interested in this "new" transmission that was probably faulty from sitting on the shelf. If "it sat on the shelf" for a long time, shouldn't it be put right?

 

[1 Lucky Texan]

well, the Duty Solenoid C isn't stuck - so that's good.

hope the fluid change and/or additive works.

 

[mdeholl]

The mechanic suggesting the limited slip additive said he will make good on any repairs. The problem is he is 125 miles away. An easy fix is what I'm hoping for.

 

[CNY_Dave]

Did the FWD fuse thing and didn't have any problem. Guess I have torque bind. The previous owner is a master subaru mechanic who put in a brand new transmission. He said the transmission was new but probably been sitting on the self for some time. He recomended adding a small amount of GM Limited Slip Additive to the transmission oil. Has anyone had any experiance with this?

Oh boy, I hope he put a trans in with the correct final drive.

Legacies and H6 outback automatics get 4.11, H4 auto outbacks get 4.44 final gearing.

Gearing mismatch would look just like torque bind and would disappear with the fuse in place.

And, this is not a VDC, I assume, as the fuse actually did something.

 

[1 Lucky Texan]

Oh boy, I hope he put a trans in with the correct final drive.

Legacies and H6 outback automatics get 4.11, H4 auto outbacks get 4.44 final gearing.

Gearing mismatch would look just like torque bind and would disappear with the fuse in place.

And, this is not a VDC, I assume, as the fuse actually did something.

whoa - excellent point.

 

[CNY_Dave]

Whoa!

 

[1 Lucky Texan]

Whoa!

 

[plain OM]

Oh boy, I hope he put a trans in with the correct final drive.

Missed that really critical factor. I'm just too trusting . . . .

The previous owner is a master subaru mechanic

 

[mdeholl]

OK guys, I took the Subaru Master Mecanic's suggestion and put two oz of GM Limited Slip Additive (snake oil) into the transmission oil. I could not believe the difference - the car runs perfect. No torque bind. The best $12 fix I ever had.

 

[CNY_Dave]

Gen 2 H6s are far enough between that I could see an experienced person missing the H6 has a different ratio. Not likely, I would say, but possible.

I'll have to remember the lim-slip additive trick.

 

[mdeholl]

Remember the limited slip additive must be General Motors/AC Delco. Must be something about their formula.

 

[robguz]

I was having similar issues with my '04 outback H4 with manual transmission. From a lot of threads I gathered that it was torque bind, but wasn't 100% sure. My mechanic told me it was "the suspension", but I wasn't sure exactly what he meant by that...

The thumping would happen at slow speeds and a tight bend radius, particularly when the car had been running for a long time (I'm thinking it was worse when things were really heated up), and was worse when the car was full of people / gear.

I checked the transmission oil and found that it was low. I drained it, filled it with fresh 75W-90, and added some (a few oz) of the aforementioned limited slip additive (it wasn't the GM-specific stuff, but the tube said it was compatible with GM's so I figured it was close enough to the stuff mentioned in this thread).

The problem is almost completely eliminated. I think it may never go away fully, but it's way better. I'm curious to see how it performs with a fully-loaded car...

The transmission oil was down to ~2.5 L when I drained it. 3.5 L is recommended by the service manual, so it was quite low. I'm glad I caught it before any serious damage was done to the transmission and will keep an eye on it. There are ~105K miles on the car, and it seems like the previous owner didn't take incredibly good care of the car (I've had it since 85K miles). Is it normal to lose that much transmission oil over 100K miles?

In any case, thanks for the suggestion mdeholl - seems like it worked for me as well.