i have had 3 motors in my car and all of them the gauge reads under 15 psi at idle when hot. could this be the gauge?

One of my thoughts was could theyre be air in the line to the gauge? causing a false reading when hot? be cause this oil pres. problem had me really confused with the first 2 and now i have a 406 in it, that was fully machined and im lost. thanks

 

Are we talking about the factory dash oil pressure gage and sender, or an add-on aftermarket gage?

 

add on, its sun pro

 

Air in the line will not do that. They always have air in the line. You could bleed it out easily enough by unhooking it from the gauge and cranking the motor, and let oil come out until all the air is purged; but over time, it will get air back in it again.

Something exists in common with all 3 of these motors though; either the gauge is wrong, or someone made the same mistake in all 3 motors. Were any parts re-used in all 3 of them?

Try hooking up some other gauge first.

 

the first motor was a 305 we rebuilt it and put all new bearings in and put it together, it would carry around 20 at idle.

The second motor was a 350 with a turned crank that plastigauged around .01-.03, it hadly carried 10 when hot in gear.

and the one im working on now is a 406, fully machined block, crank is .02 over.

both the 350 and 406 were in my dads boat and both buried 80 psi at idle, when hot on that gauge.

and when all three were cold they all had over 60 psi, and when i rev it, the oil pressure goes up.

thanks for any help

 

ttt