so its a 1994 impreza wrx turbo with an auto transmission.
While putting it onto any gear, it wont move with a whirling sound. The whirling sound increases with the revs as if the motors running free!
However, with a little push to the car and on reverse gear, it comes into gear and after a while it goes free again ..

So what could posibly be the fault?

 

Have you checked the fluid level in the box? Or if it smells burned at all.
If thats ok ...
It could be a faulty torque convertor or a drive shaft that has stripped its splines in either an inner or outer c.v joint, both these things could stop it moving.
Hope thats of some help.

 

could it be a diff?

 

any way i can confirm myself what the problem is before i book it in

 

I would first check fluid levels and failing that would suspect a broken cv joint etc

 

My Center diff busted on my 5 speed manual and did this exact thing....

it would catch sometimes and pull the car fine, but then, it would release and just make a whirring/grinding sound of teeth clashing with the engine revving and the car going nowhere.... my Speedo and tacho would both move when I was revving it up in gear... that is how I figured out it wasnt a slipping clutch... because that is what it felt like at first.....

I would be suspect of the center diff over everything else.... if you are getting a spinning noise in the tranny and it can be coaxed to move every once in a while, it is probably the teeth on the center diff are chewed up like mine....

my center diff had actually split itself apart from the rear case snap ring and the heavy fluid had leaked out.....

Just a thought, but it makes the most sense to me at least.......

it is inside the tranny, so, obviously, you should check all other things first (like broken cv shafts, etc.....)

GOOD LUCK!
RYNO

 

yup check tranny fluid, first thing. Might just need a top up
Tranny or drive shaft/CV issues is probably the next thign I would look too.... pretty mcuh the same as above.