Ok first timing belt replacment for a '03 Legacy GT sedan 95k on it now.  Should I bother with the water pump replace at the same time on the EJ251?  Also in my old EJ22 days we use to replace the oil pump during a T-belt chnage?  Same issue with teh EJ25??

do you trust the bearings on the water pump to last another 95,000 to 100,000 miles?

 

personally, I would change it while in there and it is accessible - along with all the idler pulleys for the timing belt as well - its a peace of mind thing.

 

Oil pump doesnt necessarily need to be replaced, but most do pull it off and check the screws on the back to make sure they are tight, and replace the o-ring.

Always, especially when it is buried in the engine. There is a 98% chance (I would say 100% but there is ALWAYS someone who says....) of it leaking between now and the next timing belt change, or worse, failing all together.

 

I hope you are also changing seals and idlers/tensioner for the same reason.

most typically replace it. they're cheap and easy to replace with the belt off.  use a Subaru OEM gasket, the aftermarkets are thin cardboard.

 

that being said - EJ water pumps rarely fail and generally give warning if they do...but i wouldn't consider it a good bet for 200,000 miles myself.

 

it is more important to replace the timing belt pulleys and tensioner - those are far more likely to fail than the water pump.  get the ebay or amazon kits for $100 - $200 with all new pulleys and tensioner.  easier to find timing component failure than water pump failure online - i've also seen plenty of timing pulley/tensioner failures and have yet to see a Subaru EJ water pump failure.  it happens, but it's rare.

 

rarely replace the oil pump, no need too.  tigthen the backing plate screws, one or more will be loose.  use locktite if you're so inclined.

All idlers, tensioner, water pump, and front cam and crank oil seals. Replace them.

Also recommend replacing the o ring behind the oil pump and resealing the pump to block mating surface.

 

Next question would be, are your head gaskets seeping? Now would be the best time to address that as well.

The idlers and tensioner are more important to replace than the water pump. I've seen the water pumps seize up, but since they run on the backside of the belt it just slips and the engine overheats instead of the belt breaking and the valves getting smashed by the pistons.