1986 Ford F-150 oil pressure loss

Tiny
SHERIFF310
  • MEMBER
  • 1986 FORD F-150
Engine Mechanical problem
1986 Ford F150 6 cyl Four Wheel Drive Manual 255 K miles

Good evening. Last week I experienced an oil pressure loss. My 4.9L oil pressure used to run 50 PSI at 2300 RPM's and 22 PSI at idle while operating at normal operating temperature. Now, my pressure is fine when cold, its around 56 PSI when cold and after engine warms up, it drops to 34 PSI at 2300 RPM and 12 PSI at idle. Oil level is normal and the only other issue that occured at the same time the oil pressure dropped was the front main seal in the timing cover blew out. I had all gaskets replaced last year due to old age and leaks. The front seal was also changed at the same time. Could this be the problem why my pressure all of a sudden dropped?
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Monday, February 25th, 2008 AT 7:11 PM

6 Replies

Tiny
RASMATAZ
  • MEMBER
Do an actual oil pressure check with a mechanical gauge if its normal and no weird knocking noises replace the oil pressure switch-might want to do an engine flush.
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Monday, February 25th, 2008 AT 7:27 PM
Tiny
SHERIFF310
  • MEMBER
I forgot to add I use AutoMeter Sport Comp mechanical gauges. I am the original owner of vehicle. Oil has been changed every 3000 miles like clock work. I even went thru the effort to replace gauge thinking it may be bad. Still reads the same.
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Monday, February 25th, 2008 AT 7:42 PM
Tiny
RASMATAZ
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For me your oil pressure is okay
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Monday, February 25th, 2008 AT 8:15 PM
Tiny
SHERIFF310
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Thanks for your replies. Do you have any ideas why my pressure dropped so much in such a short time? I know things don't last forever but in your opinion main bearings starting to go?
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Monday, February 25th, 2008 AT 8:24 PM
Tiny
RASMATAZ
  • MEMBER
Could be a sloppy oil pump/cam/rod/main bearings-
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Monday, February 25th, 2008 AT 9:29 PM
Tiny
SHERIFF310
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I am going to fix the front main seal and switch from 10w40 to either 20w50 or straight sae 30 and see how long she will go.
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Tuesday, February 26th, 2008 AT 11:10 AM

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