Hello! Merry Christmas everyone! So my capillary oil pressure gauge is reading ~20psi at idle. It was about 40 last week and at 30 a month ago! Any ideas? Is there an easy, quick way to figure out if it’s a bad oil pump?
-Krystal 
From what I know the oil pumps are usually the last thing to go wrong. Many times its the piston rings or other components.
Maybe try another gauge.
Mine kinda does the same thing 20 pounds at idle & 45-50 at highway speed. It may mean the engine is getting tired, mine has 131,000 original miles but I will not be messing with it in the near future. I don’t plan on touching for a long time. As long as you are not hearing any noises from the engine you might just keep a eye on it. By the way I pulled the engine out about 15 years ago to redo engine compartment, new gaskets ect I put a high volume oil pump on it. Then I heard high volume pumps aren’t the best for the engine, works fine though, for me. This is on my convt. 351C 2V
Standard disclaimer: I am no expert, but the rule of thumb I’ve always heard is 10 psi per 1000 rpm and you’re good to go. 20 at idle doesn’t seem that bad, especially if the engine is warmed up. I don’t like the trend, however, so as the others said, keep your ears open for unhappy noises.
Please provide a history of the engine. What oil and weight are you using? What filter? How many miles and what mods have been done? Was the engine fully up to temperature for the readings you provided?
Hey there! Thank you so much for your reply! I’m using 10w40 Mobil one synthetic with a synthetic filter. There’s about 80k on the engine which is a 302. As far as the mods go, nothing special. It’s all stock other than the elderbrock carb. I’m kind of worried now because I found oil in the coolant reservoir… or at least what appears to be oil. I flushed the reservoir 8 times (running the engine to normal temps each time) and when I drained the water into a plastic pan, there were globs of brown rust looking deposits that stuck to the sides of the pan. Is that rust? Or oil? I don’t know… I wish I took some pics! I’ll drain it again tomorrow. I also put in some Preston flush a couple of days ago to help flush the coolant system. I’m really worried that it’s a head gasket… 
Merry Christmas! I hope you had a great day! 
Oh and yes, it was operating at temps, which hover around 190! Another issue I guess… 
It is so hot in the car that I am seriously tempted to drive around in my bikini lol.
Are you losing oil? Have your drained the oil and looked to see if you have water in the bottom of the pan? You may not have both oil and water exchange places with a blown head gasket, but you can. I use dino oil in all my old cars, not synthetic. Maybe you’ve knocked something loose and have some clogged oil passages, thus the lower oil pressure? If you hadn’t noted the changing downward trend of the pressure, I wouldn’t worry about those numbers. Best way to flush the coolant system is to use one the the filters in the top radiator hose after having your radiator either re-cored or rodded out. And 190 is a fine operating temp. I think someone earlier told you that a stock t-stat from the factory is 195, which is what I run in all my cars…at least the FEs, IIRC. A blown head gasket with either get you persistent, obvious white steam coming out your tailpile, even after the car has warmed up, and/or wild and unexpected temperature fluxuations. You’re car will just warm up and up and up to red line, or it’ll be OK for awhile, then all of a sudden quickly get very hot–it doesn’t hold at 190 for a predictable period of time. Good luck.
Crystal, is this the same 302 that had the high oil pressure? If it is, it sounds like whatever you did just got it back to normal.
A few more thoughts. In another post you talked about replacing the thermostat. Reread those posts. What did you end up putting in. The commenter is right that 190 is not a problem unless you are keeping it from really overheating by running the heater - bikini comment. Where is the sensor for temperature in the intake manifold. If it is in the hole adjacent to the head where water comes out of the drivers side head, it will show a hotter temp than the mixed average.
As for oil, I go with the dino side as previously mentioned. You are taking less risk with an oil that has significant zinc/phosphorous in an old flat tappet engine. The Mobil 1 filter is great and I would suggest continuing to use that. I would change to Valvoline MaxLife 10w30 or VR1 oil. After that figure out what the normal operating pressures at temperature are. You are probably OK.
As for the rust/stuff in the coolant, you probably, as previously mentioned, need to get the radiator cleaned/redone. Assuming it is a 20 inch wide, you could also buy new. Get at least a 3 core. Others will chime in on options, but check the Scott Drake options, then put the part number in Summit and buy from them. They have extremely fast delivery and usually the lowest prices and great service. You may not pay much more than to have the existing redone and it is probably only a 2 core.
Pictures please.
Agreed,
Pictures are needed if an accurate response is expected.
