Oil pump removal question

[vasy]

I have a 96 OBW, 2.5. The 97 FSM on oil pump removal says to drain oil and coolant, remove water pump, then remove oil pump. I'd like to know: (1) if water pump must be removed in order for oil pump to be removed; (2) why draining engine oil for the purpose of removing oil pump? Is it necessary to drain oil? Oil pan is lower than the pump. If I let the car sit overnight before I start the job, how does draining oil help with oil pump removal? (3) When I reinstall oil pump, is it better (easier to get the whole job done) to drive in the crank oil seal to the pump when I still have the pump on the floor, or is it better to install the pump to the block first, then drive in the seal? I'm afraid that if driving the seal with the pump off the car, although it's easier to drive it in but during the last moment of the job when I attach the pump to the block, the Utra Gray sealant might get messed up because of unintended movement/friction. I plan to reseal the oil pump and it's my first attempt to deal with the pump.

[porcupine73]

Hello. The water pump doesn't have to be removed to remove the oil pump, at least I never have. Sometimes the rubber edge on the water pump that seals up against the oil pump (just to keep the timing cover sealed) rubs or is kind of tight but it isn't really an issue.

 

The engine oil does not need to be drained. A small amount of oil might come out when removing the pump but nothing major.

 

It's easier to get the new crank seal on the oil pump before putting it on the engine. Then I grease the crank and use care around the key so as not to rip the new seal.

 

Permatex ultragrey is one of the Subaru listed alternative sealants for this job. Make sure you get a new o-ring too, and make sure it stays in place while putting the pump back on. I have this job to do coming up on my '94 and am going to try an anaerobic sealant such as Loctite 518 instead after discussion with an experienced board member.

 

And tighten and loctite the rear rotor case cover screws (I'm assuming that's why you're doing this job anyway).

[GeneralDisorder]

Don't need to drain the oil.

 

Don't need to pull the water pump (though it makes access a bit easier).

 

I always take the oppotunity to install the seal while the pump is off. But I do a lot of crank seals without removing the pump as well - EJ pump's rarely need to be removed except in the few cases where checking the screws on the back is warranted but that's only a few models. They don't generally require a "reseal" as the RTV doesn't ever fail in practice and the o-ring behind the pump is not usually a neccesary replacement either. EJ oil pumps are relatively trouble-free units that often last the life of the engine.

 

GD

[vasy]

And tighten and loctite the rear rotor case cover screws (I'm assuming that's why you're doing this job anyway).

 

Thanks. Yes, that's why I need to remove the pump. Nothing wrong with it but since I'm there to replace the idler pulleys, the oil pump is right next door.

 

My thanks also go to GeneralDisorder. I'll figure out whether to install the seal while the pump is off or on the car in the last minute. This is my first oil seal job. I'm going to do a dry run with the old seal to see which way is better for my skill level.