BP5 GT-B Trans Issues

[legacyspecb]

I recently added a trans cooler to my 03 Legacy GT-B so I can confidently use it to tow the boat. I installed a Davies Craig HydraCool cooler designed for 2-4 litre engines and replaced the trans fluid with Penrite ATF FS (Possibly where I went wrong). 

 

I installed the cooler after the filter in the passenger side guard which is before the heat exchanger. I decided on this so that I could remove as much heat as possible to take the strain right off the engine cooling system. The cooler is mounted so that it pushes the fluid from the bottom to top which is the recommended orientation for it.  I topped up with the Penrite ATF FS, drove it for a bit to make sure it had filled up the cooler, then topped off again. 

 

A couple of weeks ago, I towed the boat (approx 1500kg) to Taupo for the first time. Up the hills I would put it in to tiptronic and hold it in 3rd. Approx 4,500 rpm all the way up and didn't have to give it more than half throttle. The temperature gauge didn't move at all, but up some of the longer hills, it would start to beep and the display would just have a " - " instead of showing the number of the gear I was in. It would still let me shift, and no other warning lights came on. Changing back to drive would stop the beeping and the car was driving as normal. It wasn't a hot day (car was reading 18 degrees) and with the size of the trans cooler I would be suprised if it was a temperature issue. Also the temp gauge didn't move so the gearbox wasn't heating up the coolant through the heat exchanger. 

 

The fluid doesn't smell burnt, but now after the trip it sometimes doesn't shift down when the gearbox is still cold. Putting it in tiptronic and shifting down still works.

 

My thoughts at the moment:

• Need to add more ATF to allow for the added volume of the trans cooler and extra hoses
• Penrite ATF FS is not a suitable substitute for Subaru ATF-HP and it's only under a lot of stress that it causes issues

 

I've done a bit of research and it seems like the ATF can make a big difference, but I haven't found anything about the beeping issue. Will be interested to hear your thoughts.

[Andy_Mac]

Have you got a obd2 cable? Have you checked if there are any codes active for the trans. 

I've had a quick gander through the service manual but couldn't find anything regarding the flashing line where the gear could be. 

[legacyspecb]

No I don't have an OBD2 cable unfortunately. I've done a bunch of research and still haven't come up with anything. Talking to the dealership was totally useless, I knew more about the car than they did. I'll be doing the same trip again in a week's time, so it will be interesting to see what happens. 

 

I tried to track down some Subaru ATF-HP with no luck. The dealership didn't have any, and they recommended just buying any old multivehicle from Repco... The fluid I have is compatible with Nissan Matic J which is a listed alternative to Subaru / Idemitsu ATF-HP so I'm starting to think it isn't fluid related. 

 

I know Subaru's aren't exactly known for their towing ability, but I would have thought with the upgraded trans cooler it would be able to handle it just fine. The mechanic at the dealership suggested perhaps taking it a little easier and that I didn't have to keep it at 100 all the way up the hills....