Last night i noticed that my oil pressure guage , would jump to 60psi after it would get to about 3/4 of the way at about 40 psi , Like it was grounding out , then after a while it acted normal , i figure it might be the sending unit , or maybe the wire grounding out, anyone comeacross this before?

Thanks again for any help.


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Pino
91'Formula
LB9 305 TPI 5-speed
WS6 17" wheels
Eibach Pro-Kit Springs
Hotchkiss STB
SLP exhuast
SLP Cold Air Induction
CatCo Hi Flo Cats
http://www.geocities.com/MotorCity/Garage/5654/mur91.jpg

 

Fist things first check your oil. It could be sloshing around in a fast stop or accelleration and when low the pump maybe sucking air causing the fluxing. If the oil is good it very well could be a ground or shorting wire. Also a bad sending unit or even the oil pump going bad.

 

Oh yeah when my sending unit went bad my gauge went full up on the high side.. it didn't go low. But I don't know it still could be your sending unit

 

I wasnt really driving hard , i was just cruzing, Its just real jumpy, not a smooth flo

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Pino
91'Formula
LB9 305 TPI 5-speed
WS6 17" wheels
Eibach Pro-Kit Springs
Hotchkiss STB
SLP exhuast
SLP Cold Air Induction
CatCo Hi Flo Cats
http://www.geocities.com/MotorCity/Garage/5654/mur91.jpg

 

Well in that case I don't think its your sending unit but you can try it. Its a cheap part like 10 bucks. See if it fixes it.. If not just clean it up and return it. To me it sounds more like a wire problem or your oil pump on its way out. Check the wires first because they are the easiest to do. Believe me it sucks changing an oil pump in a f-body, because of the crossmember. Also you didn't say if you checked your oil or not? Is it totally full? Always check the simplest things first.

 

That almost certainly is the sending unit. They're a variable resistor, with a wiper that moves on a wirewound element. When the wiper loses contact with the element the gauge reads full-scale. What you describe is a fairly common failure mode for those things. Like 327 said, it's a cheap part, so you can just troubleshoot by substitution without killing your bank account.

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"So many Mustangs, so little time..."

 

Cool thanks guys , Thats what i figured it was , oil is full , car runs super , so i wouldnt think it was the pump. Ill check it this weekend , oh yeah, is the sending unit, down by the oil filter , or up top at the back of the intake? I just dont feel like digging for it in 20 degree weather.

Thanks again