Oil Pressure Problem?? (1 Viewer)

[CruiserFlips]

Hey Everyone,
Went through the forum and read all I can about diagnosing vacuum and oil pressure. I changed out my oil pressure gauge (mechanical) and temperature gauge (electrical). I need to add a vacuum gauge and tachometer. My question to all is what should the oil pressure gauge read at idle and at freeway speeds (55-60 mph)? I have a '70 FJ40 with a stock '71 F engine. The pressure at speed reads about 50-55 PSI and when I come to a stop it hovers at about 15 PSI. I read in the manual that the pressure should read 60 PSI at 4000 RPM. ???
I plan to add the vacuum and tachometer this week but the pressure concerns me since I don't really know what it should read. Thanks in advance for all your help and I am glad I fould this site.

 

[Rice]

15 and 50 psi oil pressure is very good pressure. Be happy with those numbers and enjoy your F engine. Because of the oiling habits of an F be sure to change the oil frequently and use only top quality filters (search for other conversations on filters and oil that Dianna was dared to start).

Rice

 

[Poser]

What brand and weight oil are you using....just curious...

 

[CruiserFlips]

Just changed the oil last week. Currently have Castrol 10w-30 and I am using a Fram Extra Guard filter. I live in Southern California near L.A. so I figured 10W-30 would be okay. Any help is always appreciated.

 

[CruiserFlips]

Well I just read the thread on oil started by Dianna. Would the oil weight make a difference in the oil pressure? I was going to use 20w-50 when I changed the oil last. I've always had good luck using Castrol (knock wood!).

 

[73lndcrsr]

The oil weight will can a difference in the oil pressure. I think the bigger factor is whether or not the engine will respond well to a lighter oil. I have been told that the oil weight is factored into the overall engineering of the engine and changing it could have adverse effects. In this case could just be the lower oil pressure. I think toyota recommends 10w-40 in warmer climates for the F and 2F, but I could be wrong. Although I don't see anything wrong with the numbers you are seeing.

My 2F runs between 35 and 40 psi at idle and about 60 psi at running speed. I use Castrol 10w-40 year round.

 

[folsom50]

I just happened to be looking up oil recommendations in the Ellery manual and seen that the min. oil pres. for a 2f at idle is like 4.6 psi.

 

[Rice]

The problem folks often find themselves a victom of is thinking thicker is better. In most of the cases it is not. Oil is the only way of removing heat from the bearings and, therefore, must keep a good flow to it. While a thicker oil can increase pressure it also makes the oil harder to flow. The same is true when it comes to trying to get oil through an oil filter. The old days of "10 psi for every 1000 RPM" is a thing of the past that racers put aside years ago. They found that putting too much pressure on the oil was, in fact, heating it. For a properly clearanced and balanced engine high pressures aren't required ... that includes stock motors. Stick with the 10W-30/10W-40 ... no thicker ... and use a synthetic if you can. It's less affected by temperature and flows better.

 

[redrock]

Toyota specifies that the oil pressure relief valve opens at 44-50 psi (slightly higher for the 2F.) I have never seen a Toyota specification for minimum hot idle oil pressure on the F or 2F; however, their minimum for the B and H series engines is 4.3 psi. If your mechanical gauge is reading correctly, the oil pressure should max out at about 50psi.

Rod, main, and cam bearings are a hydrodynamic (floating) design, and require oil pressure to carry their loads. Oil that is too thin, or bearing clearances that are too large will not maintain oil pressure, and the result will be bearing knock and then, failure. A thicker oil can compensate somewhat for worn bearings, as it won't "leak" through the bearings and can maintain oil pressure.

Manufacturers now recommend very light oils simply because it takes less power from the engine to pump that oil, and that translates to increased mpg.