SuperSubaru

So I finally put the OB on the ramps this last weekend to find out where the massive oil leak is coming from - looks like the timing cover gasket (guessing) was over torqued and pushed out. I am due for new belts anyway, so I will keep adding oil and dealing with smoking exhaust manifolds until I can save the coin to have the belts - and whatever is leaking underneath the cover replaced. I need a new front O2 sensor, so I figured I could do that in a snap as well. But alas, it is placed neatly at a point where nobody could change it out easily. But I noticed something else... It looks as though I could unbolt the exhaust manifold from the block (3 nuts, each side) and let gravity pull it down to allow easy access to the front O2 sensor.... Is this true? Do you have any other tricks I should know about before tackling this one? I will be using a universal, since the business ends are identical - I need room to do some splicing and soldering of the wires as well.

I have two kids, 4 and 1.5... both in car seats in my '97 OBW. I am pretty tall, 6'3" - so the kids readily kick the back of the seat, but other than that... plenty of room for me, wife, kid #1, kid #2, large cooler and camping gear or the great dane

3-wire sensor = two heater, one signal, sensor body ground to exhaust 4-wire sensor = two heater, one signal, one harness ground (less noise, cleaner signal) With the two heater wires spliced together pre-sensor, then essentially your heater would never heat up, your ECM would see very weird resistances in that circuit and could through things for a loop. The sensor itself is probably fine, it's how your ECM is reading both the signals that is probably causing havoc. If you can see the splice and you could probably fix it yourself, but pick up a manual and verify what the wires are supposed to go. Make sure you use a weather tight seal, otherwise you will probably end up doing it again.

The sensor body - business end - is identical (assuming the same manufacturer). If you have a soldering kit, or weather-proof connectors, the universal would do exactly the same job as the OE style. 3-wire = 2 heater, 1 output signal, the sensor metal shell does the grounding 4-wire = 2 heater, 1 signal, 1 ground Save the money.

kimokalihi - Do you still have the 3.90 differentials? I have been looking for some if they are in usable condition.

First let me start off: I am a mechanical engineer, I emphasized my career in engine design, and still work in the field. Peak torque and HP are for marketing and advertising. The number of times the general public ever uses these numbers is less then 1%. Gas mileage has less to do with RPM and much more to do with throttle position. Peak torque and HP numbers are attained at WOT (wide-open throttle). I agree torque is more important to fuel mileage. If I build a brute of an engine with gobbs of torque, I could cruise @ 80mph @ idle. But mind you that would be a pretty big engine, and probably diesel. Car makers don't design for gas mileage at real world expressway speeds (70-80MPH). They design to do the best on the EPA testing (if I remember correctly is like 50-55MPH), again for advertising purposes. So look at your RPM at 55MPH, top gear. That is the engine speed your engine is tuned for (it may be your peak torque RPM, it may not... ). This is the RPM I am going to try to put my sube at, but rather at 75MPH.

I feel your pain. My 97 OB M/T is the same. I have been looking for a way to solve this for a while... this car is capable of over 30MPG if it was just geared better. If I can find a spare car for a while, or a mechanic that knows Subaru, I would like to do a diff swap with a SVX (3.54 gears) into my OB M/T (4.11 gears). I could care less about off the line acceleration... I drive 100 miles a day and need something that will cruise at 80 without screamin'. The A/T have taller gears than the M/T.

I have a 97OBW that I drive 100 miles every day for work. I am looking to boost MPG. Here is what I plan... Swapping SVX differentials (3.54) with my stock ones (which are either 4.11 or 4.44 - depending where you look on the web). If I can't find a SVX, then there are WRXs out there with 3.70s which would still be better. After the swap, I will put on the UnOrthodox underdrive pulley to help remove the parasitic losses and help spin those tall gears. I am hoping for consistantly over 30MPG with nearly all highway driving. ANYBODY WHAT TO SWAP DIFFERENTIALS???? if there is a good mechanic out there, we could probably do it in a weekend, everyone wins, taller gears for me, shorter gears for someone that wants the acceleration. I am outside of Rockford, IL (about 1.5 hours west of Chicago)... email me at kevin.koss@us.army.mil

I am trying to squeeze a few more MPG out of my 97 Legacy Outback. Stock differentials are 4.11 gears, and I believe there is an available 3.70 gears from other applications of different years. Does anybody know if this is possible? Do you know what applications carried those 3.70 gears? FHI p/n is 722011001. Maybe I could find a loaner car, from the dealer, they want like $2400.