I thought about checking the relief spray in the oil pump but I can’t find any specs on what it should be. A friend of mine says the caterpillar actually has a spec for their springs. like for checking valve springs but I found no such specifications for GMC trucks oil relief spring. Thank you all I’m gonna be trying very many different ideas you fellows have given me. Dave

Last edited by Davie Boy; 09/29/2024 10:29 PM. Reason: Poor grammar

1957. GMC F350