Oil pressure issue

[jofe4]

Now The rule of thumb for oil pressure is 10psi/1000rpm, but my low oil pressure light is coming on at idle 500-750rpm. now if I raise the rpm to 1000 light goes away and I get oil pressure back. Is my pump going out or is that just a very low idle for the car and the crank driven pump juts doesn't pump fast enough that slow? It has 10W 30 in it now im goingto put 5w30 in it tomorrow and see if it fixes it. if not im going to turn up the idle to 1000 till it works right. what do you guys think?

 

[bryanwheat]

Check the pressure with a mechanical gauge if in doubt. I don't see how an oil with a thinner cold weather rating is going to give you better oil pressure. IF anything i would try something thicker. IF your oil pressure is truly that low and the sensor isn't just bad than you have other problems that thicker oil won't fix.

 

[WES_393]

^ +1 The W number is the consistency at colder temps. The only difference you might notice is faster cranking at low temps, it won't raise your oil pressure at operating temperature. You should run 20w50 anyways so try throwing that in and see if it helps. You should also look into getting an aftermarket oil pressure gauge. The stocker isn't graduated to read PSI so it should only be thought of as a none/low/high guage.

 

[j_biggz]

Both of them are right. I had a 97 Gst with 160k and it did a very similar thing with the stocker gauge and when I hooked up the mechanical gauge it read almost nothing at idle. To me it was basically a rebuild situation and I sold the car about a year later. Still runs around but I just know better. Good luck and I hope that its not a rebuild for you. Mine would read 0 at idle on my mechanical and would read normal when driving. My Gst I have now reads about 12ish at idle @ 800rmp. Hope that helps

 

[DSM1G90]

Thing we have to remember, esp with stock gauges, is that it only shows pressure present, not the actual lbs sq in.

If you got oil coming up to the head even with the light on, you've got decent pressure, but it could mean that the connecting rod bearings are tired and can't hold up the pressure at low RPM, but goes up when RPM's are slightly increased and light goes out.

Seen this bunches of times on motors with tonnage of miles on them. And if that '91 Talon has the original motor without a rebuild, chances are the rod bearings are definitely tired (as mentioned above-a rebuild was in order)..and I bet oil consumption is close to 1000 miles/quart.

It may help with the 20w/50, but seen some drop "STP" or "Motor Honey" just to thicken up the oil so the light goes out, but definitely not the cure-all for this situation.

-DSM

 

[turboglenn]

How many miles on the car? Could be the oilpump failing or it could be excessive clearance in the main and rod bearings as well as others causing the pressure to be low. If the light comeson that shows there's No Pressure at all, the stock gauge is worthless thoiugh. I cna get my light to turn off at cranking speeds so i leave thathooked up and still have a manual gauge in the car too, I see about 18or so hot at idle of 900RPM and 22psi at 1000RPM idle (i keepmy idle in those areas)

you need to see how much you're making at idle and through out cruising rev range.

YOu may getaway with tossing somenewmain and rod bearings in (do this with engine in the car, just pull oil pan) and you might want to do the oil pump which is a bit morelabor intensive since you have to pull all the front accessories off like the pulleys and belts as well as the timing belt to get the front cover/oil pump assembly out to rebuild it.. but when you do that you can pull thebelt for the front b-shaft and then do a stubshaft for teh rear balance shaft (part ofthe oil pump and the miragestub shaft eliminates the long b-shaft when you bolt that to the oilpump gear.

Check pressures at higher revs..ifyou can get into the 60psi range i'd say it's bearings you need to swap, oil pumpsreally don't havemuch about themto fail

 

[jofe4]

Ok the engine has 104K on it. I just raised the idle from 500-750 to 800-1000 and it keeps the light out. I looked up the specs on what oil to run and I saw you can run almost any weight oil other then 5w20. She seems to run better with the 5w30 I put in it on friday. dont think it is rod/main clerance as it would show its face in other ways as well (AKA loss in power). Car is stock besides a 2 1/2in cated turbo-back exhaust with stock muffler(I know dumb bought it that way) and a manule boost controler set to about 12 psi.

 

[bigschnard]

My 93 Mitsubishi eclipse gs. Has low oil pressure at idle also. Almost to nothing all the way to the low mark. But the light doesn't come on and seems to be running fine. Checked the sending unit wire and its on there pretty snug. But while running highway speeds it goes to about middle ways to about 3/4 of the way could it just be the guage or sending unit not reading correctly. Car does have high mileage. Around 223000. But unsure of the past of the car. Any help would be greatly appreciated.

 

[007jimmy]

The stock gauge is pretty inaccurate. You need an aftermarket gauge to really see what your oil pressure is. The stock sending unit might be going bad if it's slow to respond.

 

[DSM1G90]

She seems to run better with the 5w30 I put in it on friday....

Too thin for 4G63 motors. Needs 10w/30 as the minimum - factory requirements for this motor.

 

[travs92vr4]

+1

Thinner oil, less oil pressure. Thicker oil more oil pressure.

With thicker oil and a turbo app, make sure you let her warm up a bit before beating on it.

And also, the stock gauges are "dummy gauges"... get rid of them. Always go aftermarket. They are too expensive for the basic ones.

 

[allwheelTSI]

If it really worries you, you could also put an extra 1/4-1/2 quart in it and see if that brings it up any. Just remember, its not so much pressure that lubricates and keeps bearings protected, but actual volume of flow that does the job.

Like stated above, check it with a real gauge and be sure, and if it is indeed still low, it probably is low for a reason that needs to be addressed, but what I'm saying is it doesn't necessarily mean your motor is no good right away. I've seen quite a few motors run almost no pressure at idle and run for a long time without problems.

 

[jofe4]

thank you for the help and I looked up the specs on AllData and they said "Turbo Models Above 32°F (0°C)=20W-20,20W-40, Above -10°F (-23°C)=10W-30, Below 60°F (16°C)=5W-30"

 

[DSM1G90]

dont think it is rod/main clerance as it would show its face in other ways as well (AKA loss in power)...

Try again - you can have a tight top end with compression rings in great shape, valves seating very well and good compression numbers, but a tired bottom end.

Shop does this test, but you take the sending unit out, drop the oil pan and force oil in the sending unit hole to pressurize the system.

If oil dribbles almost streams past the connecting rod bearings, they're tired.

Good bearings should hold oil to where it just barely drips when the system is pressurized.

-DSM

 

[bigschnard]

Try again - you can have a tight top end with compression rings in great shape, valves seating very well and good compression numbers, but a tired bottom end.

Shop does this test, but you take the sending unit out, drop the oil pan and force oil in the sending unit hole to pressurize the system.

If oil dribbles almost streams past the connecting rod bearings, they're tired.

Good bearings should hold oil to where it just barely drips when the system is pressurized.

-DSM

Is there any way you could do this yourself. And can you change the rod bearings without pulling the engine and without pulling crankshaft.