Basically the title.

I have a 3800SC Fiero with the oil pressure sensor from an 88 Fiero and I have been through at least a half dozen over the years.

Whenever I rev it out or downshift above 4.5-5k RPM the rubber seal on them goes and sprays oil everywhere. Some cases it only does it very briefly, but other times the seal totally fails and it starts leaking.

I have tried multiple brands, suppliers, and sometimes two of the same. However they NEVER hold up for very long.

Anyone have a solution? Would 5w-30 instead of 10w-30 help?

A most unusual problem. Is the leak at the threads or is it coming from within? If its leaking from the threads you could be over-tightening the sensor and have stripped threads in the oil filter adapter where the sensor goes..

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

isn't the sender is iffy...
More likely is something w/ oil pump and regulator likely on the pump.

Some "normal" and more w/ High volume pumps can Spike OP because reg can't dump oil fast enough at high RPM.
Put a mech gauge on engine reads 100+ PSI and likely see this.

⚠️ Warning:
Many Oil Filters can fail w/ High OP too. If can, flange or seal doesn't fail, the filter media can.
Many GM Bypass valves are in the engine Not in the filter and only flows some oil. Any engine uses PF47 52 and others have no bypass valve in the filters. This valve can "wear out" or otherwise fail or be open a lot because have collapse/plug filter media or pump/reg problems.

ACDelco has/had the bypass for OE Fiero engines because many still use same valve.

In cold weather the valve can open too depending on weather temp and oil used. Is why most GM and many others vehicles call for 5W or 0W oils.
10w is heavier at higher temps and raise OP even higher.
See https://www.fiero.nl/forum/F.../HTML/143166.html#p5 and DL the API PDF Read oil viscosity grade at bottom.

thick oil can wreck the SC and cause more problems. If you look in OM for car w/ that engine from factory is Oil Spec is likely 5W-30 to 0W-20. New cars even have 0W-16 from the factory.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

So I should note that this has happened on two different 3800s, so I doubt it is an issue with the oil pump on both of them.

It doesn’t leak from the threads, it leaks from the plug. It’s the rubber seal in the sensor itself.

I can watch the gauge during a high rev downshift and once in a while it will “shutter” I can tell the oil gets by the seal on the sensor and sprays a bit out..

same thing happened to me a few months ago. didn't know anyone else had the same issue.

Rob

Man, spraying oil is not good....I’d probably look to put in a mechanical gauge...
Maybe Ron Francis Wiring would have a better sender..

[This message has been edited by PhatMax (edited 11-06-2020).]

A few years back I ran into a batch of OPS with the issue you describe.

The sensor is failing internally.
Pull it and replace it under warranty.

I finally got a good sender, it's been on the car for years with no issues.


Put a mechanical gave on it to find out your max pressure - that will tell you if you have a problem with oil pressure being higher than it should be.

If the oil pressure is higher than it should be, find out why.