gottadrive

I had trouble starting my car this morning (flooded). But I finally got it started and headed to work. I looked down an noticed my oil pressure (stock gauge) reading 0. A little while down the road it was up at normal levels. I wasn't watching when it went up so I don't know if it went gradual or just jumped up.
So I am hoping it is just a loose wire on the sending unit or something of that nature.
Where is the sending unit so I can check it?
Is it possible that my oil pump is goin bad?

FPrep2ndGenRX7

Sending unit is under the oil filter on the back plate. It sorta looks like a mushroom. It has one wire attached to the top of it.

Fingers

Hey buddy, if that doesnt work, try the oil bypass valve shim. I had almost zero oil pressure when the car was warmed up. Now its about 2kg/cm while at 3000 RPM

gottadrive

where is the bypass valve?

Silkworm

I'm sorry, but WTF are you doing driving a car with 0 PSI of oil pressure? That's the fastest way I know of to ruin a good engine. Never assume that it's the sender, or a wire, or anything but 0 PSI oil pressure until you've throughly checked over the system.

The bypass valve is in the crank pulley.

http://fc3s-pro.com/TECH/HOWTO/OTB/otb.html

You can thank ReTED for the info.

PaulC

BoostedRotors

I guarantee the wire came off your sending unit....they love to fall off. The sending unit is a round piece underneath your oil filter...there shoud be a wire attached to the tip of it...im pretty sure that youll find yours has come off.

rx_7_driver

hey i got the same problem
i checked the sendeing unit and the wire is connected i took it of and cleaned it and it still isn't moving the gague is still siting at the bottom could it actualy be the gauge inside the car that is fucked??? because the guy ho own the car before me sad the car was in a wreck(it got hit in the ***) and ever since then the gauge never worked

turbotwista

rx7 driver it is most likely that the sender went bad the tend to go bad on me all the time. you can do like I do and just get on off of a junk yard car and try your luck.

ronarndt

Mazda makes the worlds best $80 disposable oil pressure sending unit. They just don't last very long. I'm on my third one in three years. Only real fix is to go with an aftermarket sender and gauge.

NZConvertible

That still far too low. It should be at least 4.5kg/cm² @ 3000rpm when warm.

rx_7_driver

i'll give the junk yard thing a shot if that doesn't work i will go to mazda for
cause i know i am pumping oil around in my engine i took the oil filter off and started the car and oil came flying out

halcyon4

First get a jumper wire. Remove the wire from the mushroom oil sender. Clip one end of the jumper to the wire and the other end to ground. The oil gauge should go all the way to the top, high pressure reading car running. If it does the gauge is ok. The gauge is electric so if it doesn't go up, then the wire is broken someplace.
Next if the gauge works, then go to the auto store and get a regular oil pressure gauge. Remove the oil sender and attach the oil gauge. If it doesn't read at least 15 to 30 lbs at idle and 60 lbs at 3000 RPM, then your oil pump is in trouble. Lastly, if the mechnical oil pressure is ok, then you can replace the sender unit. Oh, my gauge is messed up, the gauge reads LESS than zero when not running and only 30lbs or so at 3000 rpm, I think the needle is bent or something, but it passes the other criteria.

halcyon4

Speaking of oil, my 1986 RX smokes like a ****** until the car is up to temperature. Then the smoke clears and no problems. Anything above 2000rpm when the engine is cold smokes like a chimney. After its warmed up then no smoke at high rpm's even. Could this simply be an oil seal or something more sinister ? The engine is fine otherwise, but it's SO embarrassing when you first start it up and the 3k warmup runs. I read that there are o ring seals that get cooked and begin to leak. Obviously something seals the problem when the engine is warmed up. Either that or the Cat convert is doing a hell of a job at operating temps.

13B2QuIcKNy

same thing happened to me once.. and i checked the oil and it was full so i started driving and when i got out of my nieghboorhood .. it just went up to 60 like nothing... it was the sender though.. it was leaking anyway.. so i bought the autometer oil psi gauge.. and now under WOT over 2800 rpm its at 75 psi....

rx_7_driver

ok is there a diff between the s4 and s5 oil pressure sending unit???? cause the only car they have is a 88 gtu and i have a 90 vert. is there a diff?

Aaron Cake

iTrader: (1)

If I remember correctly (and I may not) then the threads are different between the two sensors. But I could be wrong.

rx_7_driver

i don't think there is a diff because i just went go look it up on mazdatrix and its is for a 81-92

rx_7_driver

ok here is the real Q how the f*** do i get it off??? i can bearly see it

ronarndt

RX 7 driver- Remove the oil filter to give a little more room, although it is still tight quarters. Use an open end wrench- check the size with the new unit- and make sure you turn on the base of the fitting, not on the thin sheet metal part which covers the internal components of the unit. You may need to put a "persuader" bar or pipe over the wrench to loosen it up to turn, since every one I ever removed was on really tight. You will probably need to say a few swear words for the idiot who designed the location of the sending unit on the engine, cause its not easy to remove.
Ron A.

rx-7fc

13B2QuIcKNy i just bought one today and mine reads about the same as yours

rx_7_driver

thanks for the help ronarndt

rx_7_driver

ok idid that and it still didn't move i traced the wire as far as i can, no break. could it be the dash couse sometimes the temp. gague dosn't work and i have to hit the dash and then it will work. i am alsot getting ready to do a 5-speed swap will a dash of a 5-speed work on my 90 vert auto once a convert it ??

halcyon4

Yup, if you grounded that wire and the gauge didn't move then you have a power problem. The voltage isn't getting to the gauge. So you have a wiring problem in the dash wiring. Might be a burned connector although I don't think the power used by the gauges would be high enough to burn the wires. The power for all the guages are very much inter related so if you have problems with one gauge it probably is affecting the other one. For a last check you could use a volt meter on the wire when it is disconnected from the oil sender. With the switch on the wire should read about 12 volts.

rx_7_driver

sorry to bring this back from the dead but i wanted to thank everyone for there help i bought another cluster for my vert and "poof" oil pressure. at idle its a little over 30 and at 3k its over 60, anyway thanks agian for all the help guys,

shawn

DaleClark

iTrader: (55)

That only applies to the 3rd gen - the 2nd gen senders are quite reliable, giving about 100,000 - 120,000 miles of use.

Dale