OKay people. here's my problem. I start my car and my oil pressure is fine, around 40 PSI. after the cars running for awhile (Appx 15-20 minutes) my oil pressure drops to almost 0. It's not my sending unit 'cause my engine tries to stall out at this PSI. I can get the pressure up by reving the engine but after about 30 minutes it won't come out of red line even at 4K. I'm realy confused. I just changed my oil because I was running 10w40 and I changed it to 5w30 but it didn't help. luckily I don't drive the car long. everyday but only for about 10 minutes so it doesn't get that low. Anyone have any ideas what's going on? what should I check on next? Pump? Clogged Screen? I'm confused please help.

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1987 IROC-Z T-Tops wait... GUTTED MAF!

 

its eather A) oil pump is clogged up or B) if its a higher milage engine it could be just really worn out bearings and needs a rebuild.

 

so bearings would make it start out fine then lose pressure?

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1987 IROC-Z T-Tops wait... GUTTED MAF!

 

right whats going on is when its cold, the oil is thick and makes it get the oil pressure, sence your getting good pressure at startup i highly doubt the pump is clogged, but once it warms up, the oil gets thinner and thus making lower oilpressure, sorry to say but looks like rebuild time.

 

Johnny,

Changing to a lower viscosity oil certainly won't help improve oil pressure. It will usually reduce it.

All is not lost, however. If you are getting your oil pressure data from the dash instrument, you need to verify that reading with a mechanical gauge. The dash instruments are notoriously unreliable, and should be used as a relative indication only while driving, not as a diagnostic tool.

It is fairly common to have a failing oil pressure sensing unit report an incorrect (and usually low) pressure signal to the dash gauge. If that is the case, a $30.00 sensor will get your oil pressure right back to where it should be. If the mechanical gauge agrees with the dash gauge, then you have a different problem.

As a side note, all those ten-minute drives could really be taking a toll on your engine, transmission, rear axle, cooling system, etc. You really need to periodically drive your car for some distance and duration to get all the fluids fully warmed and distributed to all the parts. I'll bet your rear wheel bearings haven't seen fresh oil for a long time, and the EVAP canister hasn't been purging for quite a while. And those are the little things.

Do yourself a favor, and take a road trip once a month or so, just to get some fresh air and let your car stretch its legs.

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Later,
Vader
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If you want to beat the World, it might reach up and pull you down...
Adobe Acrobat Reader

 

I would but the oil pressure scares me. when it starts dropping the car runs like crap, then when the gauge is reading in th elow red lines the car tries to die out and sometimes does. I'm afraid it's trying to seize up the engine. I don't want that.

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1987 IROC-Z T-Tops wait... GUTTED MAF!

 

sounds like forsure the gauge is OK, not really a whole lot you can do except rebuilt it while you can, one of these times its going to stop, and not start agian. and thats new engine assemby there

 

bah, I understand. THink I can pull it off in 4 days?


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1987 IROC-Z T-Tops wait... GUTTED MAF!

 

I'd be willing to bet money it's just your oil pressure sender that's acting up. I went through 3 brand new sensor from AutoZone until I finally got one that reads normal. The stock ones are even worse. Get a new sensor first and screw it in. That should fix the problem. As for the car trying to die, I doubt it's because of a mechanical failure. I'm leaning towards one of the sensors again, like your IAC valve needs to be cleaned or the MAF sensor is on its way out, you might need a tune up... etc etc

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1991 Z28 5.7 TPI

ZZ4 heads, ZZ4 cam, Harland Sharp roller rockers, Accel base, SLP siamesed runners, 52MM SLP Throttle Body, Hooker Headers, Flowmaster catback, MSD6A ignition, Home made ramair system, 2500 stall, bullet proof 700R4, aluminum driveshaft...

Soon to be installed. WC T5 !

 

It just got a tune up. but I'll try a mechanical sender first I suppose.

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1987 IROC-Z T-Tops wait... GUTTED MAF!

 

Jonny, I amhaving the same problem with my car Bad part is my motor has about 10 miles on it. it is a brand new GM crate motor. Same syptoms as you. I put a new oil pressure switch in when the motor was on the stand and the gage read fine for about a month or so while i tuned the car but now it is going down. where did you guys hook a manual gauge to

 

Honestly, if you were at 0 PSI you would probably know by the loud obnoxious terrible dieing noises the motor would make, or at the very least, some loud ticking noises from the valve train getting no oil. Back when I knew nothing about cars, and my brother had only been driving for about 3 months, something (I don't remember) happened, and our '88 Dodge Grand Caravan lost all it's oil on a 45 minute road trip. It made lots of loud tapping...we had no idea what it was...and continued to drive (the idiot light was truely an idiot of a light, it never came on) Made it to our destination, and made it back, the next day it wouldn't start, basically almost no compression. We got lucky, bottom line is the motor let us know it was very sick, by making loud noises! Verify that reading before jumping to conclusions. I had actually bought a cherry picker, and found a replacement motor when someone told me to check that unit, then of course I realized from that prior experience that I was a moron and should have known the motor would have complained. $30 and all fears were put to rest
Corry

 

he is saying that the engine makes noises and stalls at idle at those low of pressure dont forget, givin it was at idel with no noises then it would be diffrent, you can try a new gauge but it sounds like rebuild time, theres no way you can do it in 4 days! in 4 days is probley enought to just get the engine out and a fresh one in, figure at least a month to do everything.

 

It does kind of sound to me like the motor is on its way out. When the sensor is the problem it wouldnt make it run bad/die when the gauge went down and run better when the gauge was higher. If you find out the motor is bad, do yourself a favor and dont try to do the whole swap in 4 days. Find another way to get where you need to go. If you do a half-@ssed rush job, you'll get half-@ssed results.
peace

 

I'm not a 3rd gen TPI whiz, but my Bonnevilles have the fuel pump pressure switch and gage sender built into one unit. If that's the case with TPI, a bad unit will send low readings to the gage, and disconnect the fuel pump power - which is why it stalls out when the gage is reading low.

If it is indeed one unit on TPI...

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. 2-1/2" cat-back, ZZ4 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (ported World 305 heads, Crane PowerMax cam, Hooker 2055 headers, 3" Catco cat & 3" catback w/Flowmaster, restalled TC, Spohn SFCs).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Holley 750VS w/4150 conversion, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).

 

five7kid, a few others on my cascadecrew board said the same thing. it's not Making noise it's just dying.

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1987 IROC-Z T-Tops wait... GUTTED MAF!