I picked up this 98 outback limited with bent valves on passenger side for cheap. It has 149,000 on it but the engine and trans were replaced sometime in its life and it had newer Felpro head gaskets. Any way I replaced 2 bent exhaust valves, new head gasket, timing belt, water pump, Idlers, tensioner, and figured I'd replace the oil pump too. Its not genuine Subaru but CNS branded higher volume pump.

 

Well it's all back together but the pump will not pressure up, there is absolutely no flow. I removed the sparkplugs. Changed oil with new filter, filling filter like always, before i attemptedt to crank and pressure up oiling system. I cranked several times for about 20 seconds and nothing. I removed the oil pressure switch and cranked the car and nothing still, it is dry. I have never had that happen before. This is my first Subaru cylinder head repair and 2.5 timing belt but not first engine repair by any means. Im at a loss, I dont wsnt to have to pull.the front of engine aoart again but it looks like i.may have too. Any thoughts or suggestions?

 

Thanks

 

Jerry

Is the oil pan dented? 

Slightly but it was that way before repair and it had oil pressure.

Never had this happen on a subi. I would definitely suspect that " new" off brand oil pump. Especially if you never removed the oil pan and pick up tube. Open up the front again and inspect , maybe even install the original pump instead. You don't want your main/rod bearings running dry or you'll be splitting the case. 

Reinstalling the original pump was in my thoughts as well. At least I know it works.

There is an oring that goes between the oil pump housing and the block. I believe when that's missing, the pump won't be able to pull the oil from the pan.

I had a similar problem when rebuilding a 2.5l turbo.  No pressure after trying to crank for 3mins off and on.  

 

Took out the oil filter, cranked until oil flowed out of the filter area.  Then put in the oil filter empty and cranked again, pressure came up almost immediately.  Seems like having the oil filter filled and the pump dry would be enough to prevent the pump from priming properly.  Hopefully this works out for you.

I know the o ring is there and I reinstalled the old pump.  I will try the oil filter removal, crank and reinstall trick.  Thanks all!  I will confirm success or failure.

On a brand new pump you usually have to put some engine oil or assembly lube in it and spin it around a few times before installing. Otherwise the oil that comes in the pump isn't sufficient to build the vacuum needed to suck oil up the pickup tube.

 

I would also question the quality of an aftermarket pump. Subaru pumps almost never fail. No point in replacing it.

Engine oil pressure light went out in less than 15 seconds with original oil pump reinstalled.  Finished assembling the engine and she fired right up.  Live and learn, won't repeat that mistake.  Engine sounds good, cooling system bled out easily, cooling fans came on.  Knock sensor threw code so will replace that.  I'll drive it and prove the drive train out before putting anymore effort into it.