I have a 406 solid roller motor with a weird oil pressure gremlin.

At idle, the gauge (autometer with braided line off back of block) reads a solid 20 lbs. oil pressure.

Then from time to time while idling, the pressure drops about 3-4 lbs. and then it seems like the motor sees the mistake and it jumps back up to 20 again. This happens over and over again.

It will go for about 2 minutes normal, fall for about 4 seconds and then go back to normal again.

What can cause this?

 

my 82 with a mech oil pressure gauge did that one time too...


i disconnected the oil line to try to figure it out, put it on another gauge and it worked fine.... so then i put it back on my orignal gauge and it worked fine too...


my only theory was that there was too much air in the line or somthing, athough ive never heard of anyone else having that prob.....

i would just try disconnecting the line and reconnecting it..

 

i doubt if this will help but a buddy of mine just built a monster 400 and he used 10 30 synthetic oil to break it in.

when you start it up the oil pressure was about 50 60 psi he would take it around the block and it would drop down to 10 psi

the shop said not to break in the engine with synthetic oil cause something with the seals also they told him to run 20 50 in it

everything seems fine now.

your oil might be to thin.