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In this Discussion
- 53jetman July 2011
- kamzack July 2011
- Marconi July 2011
- ratlee2 July 2011
- walts garage-53 July 2011
262 Oil Pressure
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What RPM is the oil pressure checked at. The manual only says 40 psi at 30mph. I assume you would check it at operating temperature but wouldn't engine rpm differ with what transmission and rear axle ratio is in the car? The engine rpm's seem kinda low when going 30mph in 4th gear with the hydramatic. Just trying to decide whether to start collecting parts for a rebuild of that 308 I have sitting over in the corner.
Rich -
I'll wade in with my amtuer's observations. Most engines have a mechanical oil pump, unless your in a high end drag racer. Does your car have a light or gauge? I know what 48 to 50 have, but beyond that I don't know. Temporarily install a manual gauge in the sending unit pipe to get better idea of actual oil pressure. If op is low, remove pump. remove the cover plate from oil pump to see if there's is excesive wear. Follow the shop manual in checking the gap between the plate and gears. Check gap between the gears. A straight edge across the plate will show ya what ya have. If ya see daylight, it's worn and has too much end play to pump a full stream of oil. In the past, I've had the plate resurfaced so the gears have a flat surface to ride, removeing excessive play. Also replace the bronze gear at the top of the pump, regardless. Pump is where oil pressure starts. Pump components tightened up will make a difference in oil pressure. There may be someone in the club that could sell you a rebuilt unit.
That's my amatuer's observations,
Kim -
Kim,
I am running both a lamp and machanical gauge on my car. The oil pump was rebuilt with a new cam gear and the cover was machined flat. I don't know if the pump gears were checked by the machine shop though. When I checked my oil pressure it was running a little low at 30mph but the rpm was only about 1000 rpm since that is where the car wants to shift to 4th gear with the automatic.
Rich -
What grade of oil are you running? If you are using one of the new light weight multigrade oils, your oil pressure may not show as high as you think it should be. These engines were originally produced when most dealers recommended a straight SAE 30 in the summer months, and an SAE 20W in the winter. These new multi grade oils would have to hustle to come up to possibly an SAE 10W in actual viscosity.
JerryJerry
email: HudsonJetman@mail.com
2nd Generation Hud-Nut
HET Tech Adviser on Hudson Jets 1953 & 1954
HET Registrar of all Hudson Jets -
I'm in this far, I gonna see how much trouble I can get in.
Jerry has good point about oil viscosity. Multi vis oils,such as 5w30,5w20, (there's even 0w20) 15w40, 10w30 or 20w50 are blended to perform at the higher vis at tempeture, but will in fact always mesure at the low number. The advantage is easier startup and imediate flow. Startup is the point that the most wear occurs. Good lubricity is vital at startup.
Putting in a higher vis straight oil will give ya better oil pressure mostly because of the higher vis. It does take energy to pump the heavier straight oils, but doesn't mean better lubrication.
With the investment that's made in a rebuild of our engines, use the best quality oil that can be had. Quality multi viscosity oils, my opinion only, have the advantage. When our cars were built, engine oils were crude by todays standards. Today's engines run in vicinity of 230 degrees. The old technology oils would disintergrate a modern engines in short order.
I look at a mechanical oil pressure gauge like a fuel gauge. If it's close to a quarter at idle, your good. Somewhere close to mid range or above at speed is good.
Again, just my amauter's observations,
Kim -
Don't fool around, put Castrol 10-40 in you engine and change every 3,000 miles like I do, and now have 135,000 miles on the engine since rebuild, and can prove it by the members in my chapter, NOR-CAL, and you should have with a hot engine, 20 pounds at idle and 38 at any speed above idle. More than that are you will wear the oil pump gear out every 20 to 30 thousand miles. Don't shim up the spring as that is just trouble. Todays oil does not drain off after you shut the engine off. The reason for light oil today is for one reason, less work on the engine for better gas mileage. Walt.
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Try changing to 10-40 and use Castrol and add 1 blue bottle of STP and see if pressure comes up a little. If not, then the rods and main bearings are worn and time to replace. Walt.
