what is the oil pressure suppossed to befor a 2.8-3.1, while ther car is at idle? i think the gauge in my car is broken.

 

I show 60-80 PSI

 

Little on the high side there

I think normal, warm idle, is 20-50 or so... But yeah the gauges go bad very often so check it against a reliable one....can always rig up a manual sending gauge with an actual oil line just to check.

 

Mine has been like that since i hit my oil pan in a dip in the road about 5 years ago.

 

i have a 3.1 in a 87 rx-7, so i think the gauge is bad, i have a electric gauge that will work off of the same sending unit, so ill try that

 

I just went through a thing on this car since I've only had it shortly. I was taking care of its cooling problems and was running it at idle showing like somewhere between 40 and 80....and then one time after running about 15 minutes I look at the gauge and notice its sitting on 0

I tried again with same results. After a little running would goto 0. With the advice of another member that I should just get the cheapie 5-10$ mechanical oil press gauge at walmart I was showing 50 and then once warmed and idle slowed down significantly around 20.

I changed out my sending unit with one from get in the zone auto zone and now its showing what should be 50 and when idle slows down sometimes goes to 20ish. It kind of worries me so I check it alot but I dont seem to be having any probs.

 

thanks im going to get new gauge and then ill let you guys know.

 

before you get a new guage you might also want to take a look at the sender unit. It's usually cheaper than a guage and easier to replace.

 

my gauges in the car did the same thing, i got another gauge, and it runs just like foxrodder's thanks guys, you all helped me figure this out.thanks

 

Mine sits around 20 at idle, and runs 40 cruising.

 

u shoudl get 60 or above at idle on a cold start, once the engine warms up u should get a 15-25, and while crusing 40-50 psi, if ur oil presure is below 15 at idle id begin to worry, though what wieght oil u use will make ur oil pres vary
i happen to run 50 wieght in the summer and 20-40 wieght in the fall/winter

 

um well here in houston it gets really hot, so i run 10/30. and if it was to get cold i would go to 5/30

 

im in new jersey so in the summer its like 90+ out and in the winter its like in the 30's. i swear by the 50 wieght stuf fin the summer. ive had engines with 50,000 + miles on them that ive used 50 wieght in and they looked brand new on the insides

 

im actually going to be replacing my engine soon, so ill keep that in mind when the new engine goes in. it had 5/30 in it, when i bought it, so i just wanted to thiken it up a little, so it wouldnt make as much noise. but thanks.

 

good lord that is some thick oil to run all the time.

 

for sure.....

 

DITTO

runnin 20W50 year round.


TomP said his car would hit 0 at idle. year or two back.

 

great, now my gauge reads circa 50 when cold, then drops around 20-30. then after like20 mins of driving around the gauge drops to 0. but if i restart the car it works again? is my gauge just crazy? i have no idea.

 

if your using the stock rx7 sender and gauge it's bound to be all messed up


I drive my rx7 on 0 psi oil pressure all the time :-)
and before I aws driving it on 120-130psi of oil pressure AT IDLE!!!!

there is no way to be sure how accurate that thing is

but might I ask WHY A 3.1 in a rx7?

 

well its the rx-7 gauge, but its the chevy sending unit. i didnt put the engine in it, i bought it from a friend, who's dad put it in there. probobly because it was cheaper than buying another 13b. i dont know. im just trying to work out all the bugs, the wiring is good, the engines good. the trannys a little wierd, but nothing that cant fixed. plus i want to swap in the 3.4, and turbo it.

 

the only other possible thing I would worry about is what is the resistance reading of the stock gauge vs the chevy sending unit.
sometiems the two might not be compatible and give bad readings

 

Like I mentioned by old bad sending unit was doing the go down to 0 thing after warming up and if I restarted car it would work again.

My old sending unit had oil coming through to the electrical plug because I guess the internals wore out. The new one was sealed up tight with silicone or similar. Make sure yours isnt leaking anywhere. Even if the gauge is not the right one if it shows pressure then goes to 0 for no reason it eliminates the gauge I think.

 

You guys know that the factory specs on these engines say they sould always operate between 30 @ idle and 55psi revving?

Some of you have worn motors and I would not recommend revving very high if you pumps are worn and not producing the proper psi.

 

If we get 45-50 psi at most anything above idle why would high revving be a problem?

 

Doward and Gumby both stated they are getting 20 @ idle and 40 cruising- Thats low.

When the motor is revving higher the oil is flinging off the jouinals quicker and can starve from lack of lubrication if you are not getting adequate oil pressure. 40 is low even for cruising on these motors, but not for a SBC V8 since they have different lubrication paths.

 

pressure doesn't always equate to flow

so having a lower oil pressure doesn't mean the flow isn't there to lubricate the bearings


at times having a lower oil pressure might actually mean MORE flow. even more so being that pressure is a resistance to the flow.

 

I will agree with everything you said- However, we are not talking aftermartket setups. We are talking about a specific factory pump with specific size gallies that require about 50-55psi for that combo to get adequate flow.

 

I'm not talking aftermarket setups either


it's just like your stock fuel injectors. you up the pressure on the regulator your total flow through the injectors tends to become less. well when considering max output.

if the thingy that is supposed to regulate oil pressure decides not to work correctly and instead go mostly open your total pressure should drop but your oil flow should go up.

 

yeah but u can have all the flow u want without oil presure the bearings will make contact with the crank

 

First of all, this is Dean you are talking to just so you know.

Secondly, you can not equate a fuel system pressure with an oil system pressure- they are monitored differently. A fuel system is monitored at the rails *before* the injector spray and the regulator relieves the excessive fuel pressure back to the tank- The oil system monitors the pressure long after the source and is what registers the flow- to equate the fuel and oil is to try and measure the psi of fuel *after* the injector spray.

And you are backwards on the fuel pressure to injector spray- How in the world can you say that flow goes down through injectors when the fuel pressure is turned up- you need to do some reading my friend

 

My oil pressure is at about 60 at start up. Once it warms up it drops to around 40. It only went to 80 when the sending unit was bad....and only went to 0 the times I ran out of oil in a turn because of a VERY nasty leak I had/have

.....buuuttt I will say, I'm surprised the thing is still going. Ran on 0 quite a few times and has no problems.......I'm guessing the car WANTS it's original 2.8 and not a 3.4?

 

Well from what I keep reading on the forums these motors have been known to go many many miles. If the oil pressure is suffering a little bit and it keeps rolling for a long time I'd be fine with that. I hardly ever rev the motor out anyways since it aint a race car. I've done it like once so far just to see what it would do(not a whole lot )

I also decided to run 10-40 when I first got it because of the 0 pressure problem just in case the oil pump needed some help. I may get good or bad responses on that issue.

 

flow through the injectors might go up but then again it also it is a little limiting in a way as well. I know what I'm trying to say but I can't think of how to phrase it. but basicly I think it is somethign along the lines of once flow startsto go up it can't keep up the the pressure or something. as I said I know what I want but I can't put it through right. I keep thinking of it like electronics high resistance source can not handle much current draw before teh voltage drops fairly low compared to to at idle current.


as far as where the fuel pressure is monitored I agree a little that where the meter is placed can have a difference but I'm sure you understand what I was trying to get at.



put a pressure meter in your exhuast. shove a cork up your tail pipe and cut a 1/2 inch hole through the cork. flow goes down pressure goes up



and you just never give up with this place do you :-)