The oil pressure drops at idle as the temperature of the oil goes up. The warm oil is thinner and flows much easier.
The pump is a positive displacement pump. It delivers the same volume of oil per revolution at all speeds. When the engine is at idle, the volume drops. When the engine is at higher RPM, the pump makes more volume than can be used by the engine, so a portion is bypassed back to the pan through the relief valve. That's why the pressure levels off and holds steady through the operating speed range.
As the bearing clearance increases with wear, the volume of oil that is required to pressure the system increases. Eventually the oil pump can't keep up so the idle pressure becomes lower and lower with wear. Heavier weight oil will help get the pressure back up. Problem is, the heavier oil will be much harder to move through the oil galleys, especially the long galley going up to the rockers.
The 15w40 weight oil is a good all around viscosity for the older engines. It's thin enough to circulate when cold, and heavy enough to keep "some" pressure at idle. A good rule of thumb is 10 PSI oil pressure per 1000 RPM. So 15 PSI at idle is plenty sufficient.
We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]
Today's Featured Article - Show Coverage: Godfrey, Illinois Country Days - by Cindy Ladage. Except for last fourth of July's Old Gold show in Springfield, Illinois, I don't remember when it was so hot. Nevertheless, the heat didn't keep vendors and visitors alike from enjoying the third annual Country Day's Event. Jane Elliott said the event was originally a one man show. "Barry Seiler, owner of Country Town Farm Supply store used to invite people up to the Johne Deere store. He would give hats and a free meal for everyone that brings a tractor." Elliott said while this
... [Read Article]
Latest Ad:
Sell 1958 Hi-Altitude Massey Fergerson tractor, original condition. three point hitch pto engine, Runs well, photos available upon request
[More Ads]
All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy
TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.