8envy
New member
Hello,
I am obviously new to this forum hopefully a few of you take the time to read this post. Thanks in advance. I have a few old 8Ns and one is currently on its way back together after a bit of a resortation. For engine work, I did not do a complete rebuild, I did rings and rod and main bearings using the same size bearings as original. I also checked tolerances with plastigauge and it seemed to be ok (I think I did it correctly... not sure).
The problem is low oil pressure... nearly 40psi upon cold startup with 40w oil. Within 10 minutes of running the pressure was down to about 10psi with a wonderful engine knocking noise. I then replaced the oil pressure relief spring and plunger for an increase in oil pressure to nearly 50psi at cold start up then dropping to just below 20psi with in 10 minutes of running. So I gained a few psi but the knocking noise is still noticeable even at about 18psi. I am very frustrated because the plasti gauge tells me tolerances are ok.
I will be pulling the oil pump to rebuild it which I should have done right away. I hope to gain another 10psi. But my main concern is the knock noise. Is there anything I can do to mitigate the problem? Next size up for bearing shells?
By the way, anything above 18-20psi, the engine is very quiet and runs great.
Thanks for any input!
I am obviously new to this forum hopefully a few of you take the time to read this post. Thanks in advance. I have a few old 8Ns and one is currently on its way back together after a bit of a resortation. For engine work, I did not do a complete rebuild, I did rings and rod and main bearings using the same size bearings as original. I also checked tolerances with plastigauge and it seemed to be ok (I think I did it correctly... not sure).
The problem is low oil pressure... nearly 40psi upon cold startup with 40w oil. Within 10 minutes of running the pressure was down to about 10psi with a wonderful engine knocking noise. I then replaced the oil pressure relief spring and plunger for an increase in oil pressure to nearly 50psi at cold start up then dropping to just below 20psi with in 10 minutes of running. So I gained a few psi but the knocking noise is still noticeable even at about 18psi. I am very frustrated because the plasti gauge tells me tolerances are ok.
I will be pulling the oil pump to rebuild it which I should have done right away. I hope to gain another 10psi. But my main concern is the knock noise. Is there anything I can do to mitigate the problem? Next size up for bearing shells?
By the way, anything above 18-20psi, the engine is very quiet and runs great.
Thanks for any input!