Low oil pressure

Hi I have a 1965 Lemans with a 72 455 engine.I have developed a problem with my oil pressure being low on engine start up.It seems to take a half minute or so for the oil pressure to come up,the pressure will come up to 60 psi and stay there while its running.I thought my pressure guage went bad and instaled a new autometer guage and it is still low at start up.Can anybody give me some idea what happened?There isnt any abnormal noises and it runs really great,it just takes a short time to get the pressure up.  

Hello edrebul

Sorry to hear about your problem seems to happen occasionally here though. There should be many members with good suggestions for you here soon so the best I can do for you is ask you a couple questions to which the answer’s will greatly help others hopefully determine your problem for you quickly. Here’s my interrogation.

1. What was your min and max pressure before the problem?

2. What is it now?

3. How quickly did the pressure come up before the problem?

4. Did the problem suddenly occur or did it appear immediately after an oil/filter change etc.

5. If it occurred after an oil.filter change what oil/filter did you have before and after the xchange if you did switch to something different.

6. What is your current oil weight, brand, exact type ie with high zddp?, synthetic?, do you add zddp? Etc.

7. How many miles on engine?

8. Rebuilt?

9. Does it now have a lifter tick after it is warm?

10. The fact that your oil pressure still comes up that high and there is hopefully not lifter tick are good signs.

If your problem simply appeared out of the blue I would not drive the car until you answer the questions and get some responses from someone somewhere.

It might not hurt to drain your oil and see if it has a very slight metallic look. Also drag a magnet through it to see if it picks up any metal  either of these things would suggest a very bad problem like a cam going flat or other.

If your pressure was good in the warm weather and it is low now because the weather is cold then it is most likely the oil viscosity. You never know if you don't ask. Just another idea.

That’s all I have for you, others will have more.

Good luck thanks  

yea hi,max pressure was is 60 psi,pressure is still 60 psi after start up,oil pressure came up almost immediatly,I had the nylon tubing too tight and it was leaking oil into my oil pressure guage,I thought that was causing my problem so I changed the guage and the problem persisted.I am using valvoline vr1 15/50.problem seemed to worsen with the colder weather.I rebuilt the engine about 5k ago.no lifter tick,no noises at all.I am planning on changing the oil to 10/30 vr1 soon.I am also using an AC filter.I replaced the oil pressure line to copper so there was no chance of crimping and leaking again.Thanks for the quick response,Ed  

hello

i'm still not sure what you are saying, going through the questions by number is easier.

All i can do with the info you gave me is guess that it was good when it was warm and bad now that it is cold which was one of my thoughts above. does this sound about right?

what was your idle pressure in warm weather and what is it now?

From the info you supplied it sounds to me like you have no problem but the weather and oil viscosity. does this sound reasonable?

switching to a lighter oil like you want will help bring up pressure more quickly but your overall pressure will go down slightly. not a problem  i'd drive it based on what i've heard so far.

others may have other ideas.

thanks  

ed,
There are a few things that might cause this.. There is a relief spring/check ball in the pump that might be sticking and there is also a bypass spring and disk in the oil filter mounting housing that is there to allow oil to the motor should the filter become plugged. If that disk is gone/damaged or the spring is in someway broken it might cause this issue also. It could also be worn pump gears, a leaking bottom plate on the pump or even possible a stripped oil pump drive shaft between the distributor and pump.. The more info you can give us on the motor the more we might be able to zero down into possible problems.  
Jim,

I have seen this happen when using thick oils.
Could also be something to do with the by pass in the oil filter adapter.  
Engine builder,self taught auto body guy.
Horsepower sells engines and torque wins races

check the hole in each end of your copper line to make shur their are no restrictions. my 455 in my grand prix acts the same way with 15-40 rotella.

does it come up faster when the motor is hot?

you may need to purge the old oil out of the copper line after switching to 10-30.  
76 455/4spd TRANS AM
69 GRAND PRIX 406/5SPD