ENGINE OIL PRESSURE
I have a '91 Mercury CAPRIS which, stock, uses an '87 MAZDA 323 DOHC 1.6L engine. Engine oil pressure (stock dash mounted guage) varies from just about zero (warm engine at idle) - but just above guage red line - to about 25psi (cool engine) at or above 2.5K rpm. Is ths normal for this engine?
Engine has functioned this way for most of its 79K miles. I have not mounted a guage dirctly on the engine (in oil pressure sender port) to cross check the dash guage reading. Am planning a cross country trip and don't like the prospect of engine freezing due tp low oil pressure. Am running valvoline 20-50.
Before the trip get an exact oil pressure reading from the engine - If that is good The electrical sending unit is bad or the gauge itself. No Engine oil pressure will be near zero unless the engine is knocking like a son of a gun :) Regulating Oil pressure Cold 50-64, warm will vary on engine condition avarages around 30
Thanks Mike. Most helpful. The engine has never knocked. At cold light off today (ambient temp 48F), indicated pressure was about 50psi. Warm pressure was just about 25psi. When I stopped in traffic (engine at idle) pressure dropped to just over an indicated zero (no knock). When I resumeed speed (about 45mph - tach around 2.5K -)indicated pressure climbed clear to about 5psi. I've arranged to instrument the engine to determine actual pressure. If it varies as the guage indicates, I'm in it for relief valve repair. If it doesn't, I'll do the diagnostic on the guage, as outlined in the car shop manual. If the guage passes, I'll need and oil pressure sender which nobody I've been able to find(parts outfits-dealers) around here (LA area) has or can identify. Any clue where I can get one? Thanks again for your prompt, helpful, response. George
Mike, Oil pressure is sat. Proceeding from a finding that the CAPRIS is built on a 1987 Mazda 323 platform, and suspecting that the original Miata probably used, basically, the same engine, I came up with an oil pressure transmitter from Mazda (at no trivial expense). The winding in the original one was worn through by the its wipers producing the symptom of variable and very low to no oil pressure. I needed half shafts for the same vehicle. Miata half shafts were an exact fit. I needed a replacement left side window switch. The switch for an early Mazda MPV (available from Mazda) solved that problem. Thanks again for your interest and your help. George
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