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Hello all,
I have a bridge-ported 12a engine in my racer that was sourced from a rolled racer that was being parted out. The engine seems to have low oil pressure objectively, but it get seven worse at high RPMs. I come from piston engines, particularly old Chevy small blocks; with those engines 10 PSI of oil pressure per 1000 RPM is acceptable. My 12A keeps that ratio until about 3500 RPM and the drops-off massively. Assuming its not the gauge (and I doubt it is but will confirm) what could be causing the issue? I'm at a loss but I'm guessing its likely the oil pump. If not the pump could it be the oil seals? If I wanted to replace the pump, I'd have to pull the engine and take off the components behind the front cover, wouldn't I?
I'll try and attach a video of what the gauge is doing
Is that a mechanical gauge or electric? What type sender are you using and where are you picking up?
Its an Autometer pro comp mechanical gauge, and its hooked up to an adapter of unknown make that mount underneath the oil filter, very much like the racing beat style adapter.
I checked my oil pressure last night at 1000 rpm and I get 60 PSI.
That seems about correct as far as my 82 Mazda repair manual says. The oil pressure at idle (750 rpm according to the manual) should be between 10-26 psi at idle and 64-79 psi at 3000 rpm. I'm not sure at what RPM your engine idles, but my bridgey is idling at 2k and barely makes 20psi when warmed up...
Ok y'all, I've been scouring the internet looking for answers to my oil pressure problem and I found this on Mazdatrix's website in a how-to section describing the front cover o-rings: "What you are trying to prevent is having the gasket and O-ring squeezing out of place and blowing the oil (under pressure) into the front cover instead of through the engine. SYMPTOMS of this problem are lower oil pressure at all times, but especially when the engine is hot. A slight “squeeze-out” can give 10-20 lbs at idle, 40-55 at 3500rpm, and drop to 35lbs at 5000rpm. A large “squeeze-out” can give almost zero at idle, and maybe 35-40lbs above 2000rpm."
That seems to describe my engine's symptoms pretty well. I've also noticed a small oil leak where the front cover joins the keg. It's less a leak, and more a constant oily wetness at the point where the cover meets the iron. Has anyone had any experience with this sort of "squeeze-out" issue?
I've been contemplating swapping my 12A pump for the larger early 13b pump, so no may be as good a time as any to start that operation. I think no matter what at this point I'm going have to pull my motor...
that would be my guess. you can try the S5 13B seal (with the Teflon ring around it) or incorporate the Renesis front cover gasket whenever you replace it.
that would be my guess. you can try the S5 13B seal (with the Teflon ring around it) or incorporate the Renesis front cover gasket whenever you replace it.
You suggest the use of a gasket? Why is that? Racing Beat and Mazdatrix suggest foregoing the gasket and using good quality silicon sealant instead. I'm going to be pulling the motor this weekend and hopefully get this problem resolved soon!
if Mazdatrix and RB told you use silicone, and that's what you want to do, then use it. i trust that they told you that because it works for them. i suggested the gasket because it supposedly will hold the seal in place when the front cover gets bolted down.
I understand. If it better holds the O-ring in place a gasket may be the way to go then. I appreciate all in the input! I'm just trying to get as much info as I can from anyone who's familiar before I dive into it myself. I'd hate to ruin an engine! 12A parts aren't the easiest to find and I can't afford a full rebuild for the next couple months!
Hello all! I know its frowned upon to bring threads back from the dead, but I wanted to cap the thread off by explaining how I fixed the oil pressure problem.
I pulled the engine and removed the front cover and lo and behold the O-ring that is meant to seal the oil passageway had completely blown! The Mazdatrix page I'd read (mentioned earlier in the thread) clued me in to begin looking into the o-ring, and the oil leak that developed between the front cover and the engine keg really reinforced my suspicions. I installed a nw o-ring and resealed the front cover with silicone instead of a gasket and the engine has been running great ever since. Th oil pressure is holding steady at 80 PSI cold and drops to 60 when warmed up.
