Oil Pressure Relief Valve Stuck Open on '83 2.8L

[83ste]

It looks like I have a stuck open oil pressure relief valve. When cold the pressure will be above 80 psi at fast idle (about 1500 - 2000 rpm) which pegs the needle. Once warm the pressure settles in the normal range spec 15 - 60 psi. I am running 10w-40 oil. The the pressure will be higher when the pressure is cold, of course, but the relief valve looks like its not working with the pressure this high. I have not checked the pressure vs rpm using a mechanical gauge, but this is comparison cold/hot with the dash gauge. Is the relief valve located within the pump ? Anyone try to fix with an mild oil flush or high mileage oil with extra detergents to free up the valve?

[trotterlg]

Well, if it is stuck anything it is stuck closed. I would not put too much faith in the electric gauge however. The valve is in the pump body. I thought they need 5W30 oil? You may not have any problem at all. Larry

[83ste]

Yep - I meant stuck closed - my relief valve Dyslexia must have kicked in. With 5w-30 in this engine the oil pressure is way low, especially in the summer. Since this is the HO version of the 2.8, so want a little extra film strength from the higher viscosity. The manual recommends 5w-30 plus other various higher viscosities/temp ranges including 10w-40. I would think the pressure relief valve should open with the higher viscosity oil though.

[trotterlg]

Just because you see 80 psi doesn't mean the relief valve is stuck. I would do a reality check with a mechanical gauge, if it is stuck you will see 100 or more. Larry