1941 Cadillac low oil pressure

[hudson1948]

Workin g on a 1941 Cadillac, motor runs beautiful. When engine warms up oil pressure at idle will drop to 4 lbs. I do have an external gauge on it. You have to really rev it to get up to 25-30 lbs. Tried a stiffer spring in the oil pump relief valve and it did not make a difference. I installed an external pressure oiler and the oil came pouring out of the holes that are right next to the connecting rod journals on the crank shaft. Is there supposed to be any kind of restrictor in those holes. The motor runs great. No rod or main bearing noises. Lifters are quiet. I also checked out the oil pump and that seems to be in spec. Any suggestions would be appreciated. Thanks very much. Charles S.

[Nahuelsan]

Hi Hudson1948!

Sorry if my advise is too basic, but take a look to the oil viscosity. May be, you need to try with other one with a bigger "SAE" number. Example: 15W50 has more viscosity than 5W30. Find this data in the oil container and try with other with more viscosity. The viscosity is basically how "liquid" is a fluid (the water is less viscous than the honey). This is a parameter that varies with the temperature: the more temperature is, the less viscosity you have, and with a low viscosity the pressure drops. It could explain your "trouble": once the oil temperature rises, your oil pressure goes down.

I hope these words may be useful to you.

[Owen_Dyneto]

I don't have extensive experience with that engine but I've seen quite a few with badly worn cam bearings, especially the front one. That is but one of many places to loose oil pressure but I'd put it on my list of things to evaluate.

[Den41Buick]

I would suggest a change in oil as well. Maybe a 20W non synthetic oil. That is what I run in My 41 Buicks. I would do a compression check to make sure that the issue is not there first.