oil pressure issues

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rustest86
Posts: 308
Joined: Mon Aug 29, 2005 8:19 am
Car: 93 240 coupe SR20DET Greddy T518Z, Tomei 256* poncams, sti injectors, and fmi
Location: Lake Charles, LA

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quickish back story, i recently rebuilt another S13 SR for my car, new oem bearings and oem S15 oil pump. since day one it had what id consider low oil pressure especially for a fresh motor, 16-13 psi warm idle but had 45-55 psi cold idle. well after 550 miles it wouldnt make over 3 psi @ warm idle and started knocking. i tore it back down and the #2,3,and 4 mains were torn past the copper and #3 rod almost spun. being cheapish i got some acl race bearings, some new arp rod bolts, and used another spare std. crank i had from another motor that had good oil pressure just blew a ringland. i probably should've replaced the oil pump too but i didnt. i did add a 3mm shim to it though. with 10w40 i still have lower than ideal oil pressure, infact at the moment i have 20w50 and lucas additive just to get 14psi @warm idle. i find it hard to believe that the pump is bad. warm oil pressure with 10w40 @ 3k is around 58 psi and climbs with the revs. with the 20w50 and lucas is 70 psi @3k. i honestly think its the relief valve but it moved freely in the bore. does anyone else know of another pressure regulator or anything else that would could cause the symptoms im having? im on the verge of ordering another pump but would be mad if i go though all that work and it does the same thing. as it is right now im not driving the car until i figure it out.


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the converted
Posts: 3443
Joined: Wed Feb 21, 2007 7:14 am
Car: 99 M3 6.0l
88 Celica All-Trac (somewhere in Cali)
2020 Taco
Location: Boston

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What kind of pressures are you getting at revs? My car (bmw) only has 8 or so psi at idle but bumps way up once it's past 1k rpm.

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Hijacker
Posts: 15759
Joined: Wed Aug 13, 2003 4:57 am
Car: '92 240sx Convertible
'94 F-150
Location: Fredericksburg, VA

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around 12 psi should be your warm idle pressure. 8 psi is the cutoff for the dummy light. Around 3k, you should be seeing 50-60 psi (2.5k should be 45 psi, so I'm guestimating on scaling for 3k). Personally, if it were me, a new oil pump and cover is a hell of a lot cheaper than machine shop time to fix a bunch of spun bearings.

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rustest86
Posts: 308
Joined: Mon Aug 29, 2005 8:19 am
Car: 93 240 coupe SR20DET Greddy T518Z, Tomei 256* poncams, sti injectors, and fmi
Location: Lake Charles, LA

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my gauge is in kg/cm2, @ 2.5k its around 2-2.3 ish/25-30psi warmed up, which by what your saying Hijacker is low. and thats with 20w50 in it. i intend to run mobile 15w40 once break in is done. Back when i was KA I had seen a few relief valve springs collapse/fatigue and have low oil pressure, thats the next thing im gonna check before i commit and pull the motor again.

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rustest86
Posts: 308
Joined: Mon Aug 29, 2005 8:19 am
Car: 93 240 coupe SR20DET Greddy T518Z, Tomei 256* poncams, sti injectors, and fmi
Location: Lake Charles, LA

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well before i had a chance to check the relief valve it spun #3 main bearing. turns out the block had a cracked oil passage. oh well ive been wanting something with more displacement. going hybrid, VVTI 1JZGTE.

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Ben240sx
Posts: 35
Joined: Wed Aug 28, 2013 9:07 pm
Car: '95 240sx
awd BNR32 GTR swap
Location: Two Rivers,Wi

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that sucks man. sorry to hear it. there's a lot of debate on what's better for these cars as far as motors. i had an '89 fully built and stroked SR with a tad more wtq than whp. they were both over 400 and im tellin ya, it was EXTREMELY hard to keep up with me in the streets. hp/tq : weight ratio is a HUGE advantage with these cars. i LOVE my '95 w/the rb26dett and awd, but it feels like 2 of my '89's as far as weight goes :mad: ill keep watching to see what you end up doing


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