suprunner Posted February 26, 2019 Share Posted February 26, 2019 Motor: EJ 251 block, stock pistons EJ 25D heads, STI headgaskets Transmission: 5mt 4.11 ends Hey folks, I have a question about RPMs and oil pressure. I have noticed that if I am to drive with RPMs above 3k, say on the highway or if I'm accelerating aggressively often that my oil level will drop quickly. I know that I am leaking from the lower half-moons on each lower-rear corner of the heads, and the rear main is leaking as well. If I am to drive around like a grandmother, and stay under 70 mph (under 3k rpm) on the interstate, that the oil leak is very slow, and I can last a month (two fuel fill-ups) before needing to add any additional oil. Could I be at too high of oil pressure when I'm in the higher RPM ranges? If I'm running a #9 oil pump, would this have any effect? I've yet to check the PCV valve, as it's maybe three years old. I will have this motor out in about a month or two, and was going to re-seal (and mate to 5mt from '05 GT-t wagon) it, but I'd like to try and address the theory now. Are there PCVs that work better for high compression options, if this is a contributor? Any thoughts or suggestions will be appreciated. Greg Quote Link to comment Share on other sites More sharing options...
gbhrps Posted March 1, 2019 Share Posted March 1, 2019 suprunner, Two things come to mind. Higher revs put out higher oil pressure. I see this all of the time on my Duramax. The oil pressure gauge varies greatly from idle to higher rpms, rising as the rpms rise. And change that PCV valve. My 1990 300ZX started leaking oil out of the rear main seal at about 50 000 km. Not a great deal, but enough to leave a 3 inch circle of oil on the garage floor after every drive. I changed out the PCV valves (that car had two) and no more leaks. Obviously the built up pressure in the crankcase caused the leak because of the plugged PCV valves. Once they were replaced, the crankcase could release the pressure, and the leaking stopped for the next 18 years that I owned the car. Maybe someone else will jump in with more suggestions. Good Luck! 1 Quote Link to comment Share on other sites More sharing options...
Mike104 Posted March 1, 2019 Share Posted March 1, 2019 Use a Subaru OEM PCV valve, the parts store Chinese ones are crap Quote Link to comment Share on other sites More sharing options...
suprunner Posted March 3, 2019 Author Share Posted March 3, 2019 Thanks guys. I have a non-subaru PCV in there. When I pull the motor to reseal it, i'll throw in the OEM from the dealership. I know I can make a motor that doesn't leak. I've done it before on numerous occasions! Leaky gaskets drives me nuts. Especially when it drips on the exhaust collector-joint.... I don't really like the smell of burning oil as you sit at a stop light with the heater blowing...I've once seen a motor that had what looked like a miniature K&N air filter cone...siting on one of the Crank Case ventilation ports that sit on the top of the heads/valve covers. I wonder if that is something I should pursue.. Greg Quote Link to comment Share on other sites More sharing options...
wirelessenabled Posted March 8, 2019 Share Posted March 8, 2019 You might want to get on sourcing that OEM PCV valve. I went to my Subaru dealer and they don't even stock them. The parts guy wondered why I wanted a PCV valve. Quote Link to comment Share on other sites More sharing options...
montana tom Posted March 8, 2019 Share Posted March 8, 2019 https://www.ebay.com/itm/NEW-Genuine-Subaru-PCV-Valve-Impreza-Forester-Outback-Legacy-WRX-STI-XT-OEM/132817578967? hash=item1eec8b6bd7:g:7w4AAOSw0e9U1oiJ that is the 2002 up and this is the early one https://www.ebay.com/itm/Genuine-OEM-Subaru-PCV-Valve-Impreza-Forester-Outback-Legacy-SVX-Loyale-WRX-NEW/132746993512?hash=item1ee8565f68:g:rDkAAOSwNSxU5Szp Quote Link to comment Share on other sites More sharing options...
suprunner Posted March 8, 2019 Author Share Posted March 8, 2019 9 hours ago, wirelessenabled said: You might want to get on sourcing that OEM PCV valve. I went to my Subaru dealer and they don't even stock them. The parts guy wondered why I wanted a PCV valve. 1 hour ago, montana tom said: https://www.ebay.com/itm/NEW-Genuine-Subaru-PCV-Valve-Impreza-Forester-Outback-Legacy-WRX-STI-XT-OEM/132817578967? hash=item1eec8b6bd7:g:7w4AAOSw0e9U1oiJ that is the 2002 up and this is the early one https://www.ebay.com/itm/Genuine-OEM-Subaru-PCV-Valve-Impreza-Forester-Outback-Legacy-SVX-Loyale-WRX-NEW/132746993512?hash=item1ee8565f68:g:rDkAAOSwNSxU5Szp The one that is currently installed is one from RockAuto or advanced auto.... Think there is anything really different? Quote Link to comment Share on other sites More sharing options...
montana tom Posted March 9, 2019 Share Posted March 9, 2019 Yes, its been proven. Quote Link to comment Share on other sites More sharing options...
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