When I built this motor last year I had 65psi cold, 55 running, and about 45 idle. Now I have 50 cold, 38 running and 18-20 idle. Should I start getting concerned soon?
Standard pump with valvoline 10-30 standard oil, non synthetic. 10k on this new build, engine also runs near 205 degrees at it's hottest if that matters.
I would definitely say that isn't right BUT.. I have seen 351w, 302's and a 2.9 V6 run for years with almost no oil pressure at idle..... Of course I wouldn't recommend trying to run the engine hard, But Dad had a pickup with a 351 and if you left the truck in Drive at a stop light with your foot on the brake the oil pressure read to where the needle was barely touching the 0 PSI mark If you put it in park it would come up to about 5-8 psi. He sold the truck and it ended up getting sold again to one of my cousins and she drove it for probably 5-6 years after Dad got rid of it and he drove it for at least a year like that and pulled a camper to Florida and back (from Maryland) with the pressure not much more that that. Then I knew someone with a 302 in a Fairmont or Granada one or the other (old memory isn't too sharp anymore) that ran for years and years with the oil pressure down around the 5-10psi mark depending on idle or running at highway speed. Then I personally had a BroncoII that ran like a top from the time I bought it to the day I got rid of it and for sometime after that and the oil pressure in that would start out around 25-30psi when the engine was good and cold then drop down to around 10-15psi if the oil had just been changed and as it approached the 3,000 mile mark between oil changes the Pressure would start a little lower and when it would warm up it would drop to almost nothing at an idle with the truck in drive and foot on the brake and wouldn't come up very much when running highway speeds, if I am not mistaken that engine is still running. So it depends on what you mean by worry. If you mean worry because it isn't right for the pressure to do that then yeah you should be worried. If you mean is it going to blow the motor up??? who knows I have seen lesser things take an engine out of bussiness and I have seen at least 3 engines run like theres's no tomorrow with oil pressure worse than you just described...... The first thing I would do though is if it is an electric gauge I would change the sending unit and or put a manual pressure gauge on it to double check that it isn't the gauge or the sender.
I have heard the rule of thumb is 10 psi per 1000rpm. I have to run a heavy duty oil filter because my high pressure pump will ballon the regular ones. I run 40 psi at idle when warmed up. It gets to 80 psi when I am cranking.
Next time you change the oil filter, cut it open and see what's inside. Or if you have one of the old ones from a recent oil change, cut that one apart & take a looksee. They make filter cutters specifically FOR this purpose. You'll know real fast whether to be worried or not when you examine the insides of the oil filter! Personally I wouldn't be too concerned. Some pressure drop is normal after it gets a good break-in as clearances are loosening up. One thing I've always done is to cut open a filter...especially on the very first run-in of an engine. I discovered a while back that some Kubota tractors have a magnet built into their HST suction filters (for the transmission) which fits nicely onto the end of a FL-1A (or like on my Maverick a FL-400S) filter. If there's any steel or iron particles floating around in there the magnet will catch all of it and next time you cut the filter open you'll if you have a problem. This is probably something that should be done with a solid or hydraulic flat tappet cam on the initial run-in of the cam and lifters.
Bruce,, those numbers are equal to my 88 stang 5.0.. and it has 14k miles on it. My Stallion with a 306 carries 50-80lbs of oil pressure at all times. It has been together since 1992. I have had several Fords that ended up with lower than what we think is normal oil pressures, that run for years and years, and very well. Dan
