So my situtation is this: At idle my oil pressure reads about 15-18 psi. I'm idleing around 750 like normal, but my oil pressure is low. Oil pressure will rise to 60 as I get higher in the rpm's, like normal. So far I've replaced the Rear Main Seal ( did it when tranny was down for clutch ), Oil Sending Unit, and now the two O-rings under the oil filter pedistal ( all three things were leaking prior ), and yet my oil pressure is still low at idle. Seems like the oil pressure is fine until something opens up ( Theromostat? ). For example, tonight on my way from home, the car was still warming up on my drive home when I hit a red light. While at the light I was idleing at 1k ( Oil Pressure was at 30 psi ), then it sounded like the Theromstat had opened ( seemed more like a choke for a carb, as I don't recall a Thermo affecting idle ) and I was idleing at around 700-750 and my oil pressure dropped to 15-18 psi. Any ideas what's causing this? best I can tell I have no more oil leaks. I am useing the stock gauge to judge all this, but I never had a problem with my oil pressure until I replaced my Rear Main Seal. I doubt my stock gauge went faulty the same time I replaced that seal. On a side note also, my temp gauge ( stock ) seems to read alittle over normal temps sometimes, i.e. 3/4 or 5/8 of the gauge. Not sure if the two could be interelated or not, but temp problem was happening before the oil pressure.

P.S. will be replaceing stock oil pressure gauge this weekend now that I got my Fc3s.org pedistial on tonight.

P.S.2 And yes, the oil is full

 

You might want to replace the oil pump itself. When my motor was being built, the builder (Bruce Turrentine) replaced the pump....I think he does this for all motors he builds as a precautionary measure. Also, when you put the new gauge in, its a good idea to have a seperate (new( sender. You can get an adaptor plate from Racing Beat that'll make the install of a pressure sender (and temp sender) super easy. If I remember right, the parts only ~$50. Good luck.

 

yep, I second the worn oil pump hypothesis...rotor clearances probably out of limits, reducing the efficiency when the oil warms up & thins

 

actually the oil pumps last for quite a long time, the first thing to go is the oil pump chain, which is usally out of spec after 80-100l miles

 

Oil thermo pellet is prolly shot, resulting in low oil pressure... here's a link from Reted's web site.. it should explain everything..
http://fc3spro.com/TECH/HOWTO/OTB/otb.html

 

Hrmm, it say's on Reted's how-to, that the stock oil pressure should be between 10-20 psi at idle, but my owner's manual, and if i remember right some posts, said stock oil pressure should be 30 psi at idle. Who's right?

 

looking for a few more insights to low oil pressure and which stock pressure is correct!

Some info on the car also:
'86 Sport
78k miles
No air pump/ac-cv
rest of my mods seem irrelavent like my exhaust, new drive shaft w/ replaceable U-joints, clutch etc.

 

In the Racing Beat manual, they say 20-40PSI is normal at idle. Fifteen to twenty is definetly cause for concern. You should have a look at the oil pump chain (is it loose?) and the oil thermo pellet before switching the pump. Fortunately, doing any of the above is fairly easy and cheap and can probably be done with the engine in the car.

 

at idle my pressure sits around 30 took it down 95 last night and she sat around 60 or so ..

 

my oil pressure at idle is around 15psi or so...then it works fine around 58-60 psi when i hit 3k rpms +...according to the site this is ok.