grumpyvette
Well-known member
I got asked which end of the oil pump pressure spring gets installed against the piston in the relief circuit ? which end goes where?
"I have a Melling oil pump that I ended up welding the pickup tube on this weekend. But before I did that I took the spring out to keep it from the heat. BUT now for the stupid question, which way does the spring go back in. I am assuming that the larger end goes in first. Because if you put the smaller end in first, theres hardly any pressure to the spring"
the bigger end of the pressure relief spring goes out against the retaining pin,
yes the hole can be threaded (BUT NOT 1/4") but its generally not a good idea as the plug can back out far easier than the pin can fall out. BTW these NOT supposed to be pressure of any significant ammount against the pressure relief spring untill pressure builds at higher rpms,and installing the spring 180 degrees out can result in the piston being stopped by spring bind before the pressure relief passage is exposed, making it effectively useless. oil pressure that pushes the piston back to expose the pressure relief passage back to the suction side of the gears opens the relief passage, is what limits the peak pressure, up to that point the spring and pressure relief effect on pump pressure is non-existant
btw in the old days guys installed a washer between the pin anf the back of the spring to take up space and increase resistance, this effectively raised the opening pressure resistance about 5 psi, with the stock spring,raising the peak oil pressure before the relief passage limited further increases, adding two or three washers could bind the spring enought to effectively make the by-pass circuit useless, if you want high peak pressure, install the correct high resistance spring NOT a washer!, abd oil pressure above about 75 psi does nothing to help so thats wasted effort
"I have a Melling oil pump that I ended up welding the pickup tube on this weekend. But before I did that I took the spring out to keep it from the heat. BUT now for the stupid question, which way does the spring go back in. I am assuming that the larger end goes in first. Because if you put the smaller end in first, theres hardly any pressure to the spring"
the bigger end of the pressure relief spring goes out against the retaining pin,
yes the hole can be threaded (BUT NOT 1/4") but its generally not a good idea as the plug can back out far easier than the pin can fall out. BTW these NOT supposed to be pressure of any significant ammount against the pressure relief spring untill pressure builds at higher rpms,and installing the spring 180 degrees out can result in the piston being stopped by spring bind before the pressure relief passage is exposed, making it effectively useless. oil pressure that pushes the piston back to expose the pressure relief passage back to the suction side of the gears opens the relief passage, is what limits the peak pressure, up to that point the spring and pressure relief effect on pump pressure is non-existant
btw in the old days guys installed a washer between the pin anf the back of the spring to take up space and increase resistance, this effectively raised the opening pressure resistance about 5 psi, with the stock spring,raising the peak oil pressure before the relief passage limited further increases, adding two or three washers could bind the spring enought to effectively make the by-pass circuit useless, if you want high peak pressure, install the correct high resistance spring NOT a washer!, abd oil pressure above about 75 psi does nothing to help so thats wasted effort
