High Oil Pressure?
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3rd Gear
Joined: Sep 2024
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High Oil Pressure?
1997 F150 with 196 k miles. 4.2L V6, two-wheel drive with automatic transmission. Never used for towing or driven hard.
It suffered the cracked intake gasket with coolant in the #4 cylinder at 60k miles. I re-built the engine replacing the #4 piston and rod, all new rod bearings and a new crank (the original was a little out of tolerance) with new main bearings. I also had the transmission rebuilt while I had the engine out. During the rebuild I am pretty certain I installed a new oil pump, but I don’t remember installing a new pressure release valve. The rebuild was about 10 years ago.
I recently had a few instances where the oil pressure gauge dropped to zero. I learned that the factory gauge, really isn’t a gauge, so I installed a Bosch mechanical oil pressure gauge.
When I first start the truck the oil pressure will go up to 75 psi in winter and summer. When driving for several minutes it drops to about 20-30 at 45 mph, and will drop to about 10 psi at hot idle.
Should the oil pressure go that high at start up? Could this be caused by the high-pressure valve not working?
Thanks for your expertise!
It suffered the cracked intake gasket with coolant in the #4 cylinder at 60k miles. I re-built the engine replacing the #4 piston and rod, all new rod bearings and a new crank (the original was a little out of tolerance) with new main bearings. I also had the transmission rebuilt while I had the engine out. During the rebuild I am pretty certain I installed a new oil pump, but I don’t remember installing a new pressure release valve. The rebuild was about 10 years ago.
I recently had a few instances where the oil pressure gauge dropped to zero. I learned that the factory gauge, really isn’t a gauge, so I installed a Bosch mechanical oil pressure gauge.
When I first start the truck the oil pressure will go up to 75 psi in winter and summer. When driving for several minutes it drops to about 20-30 at 45 mph, and will drop to about 10 psi at hot idle.
Should the oil pressure go that high at start up? Could this be caused by the high-pressure valve not working?
Thanks for your expertise!
Hotshot
Joined: Jul 2020
Posts: 10,608
Likes: 2,685
From: Near Salt Lake City
Sounds good and about right to me
5psi at 500 rpm will turn on the light and 7 pounds at 700 or 8 pounds at 800 will shut it off then
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