Oil Pressure Question
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Cross-Country
Joined: Oct 2011
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From: Pennslvania
Oil Pressure Question
I read that the oil pump on a engine does not cause the oil pressure in the engine - it only supplies the needed flow of the oil - that the main bearings are responsible for the oil pressure that occurs - that is why an indication of excessive clearances in the bearings is low oil pressure - if this is so why are oil pumps designated as 40 psi, 60 psi pumps etc. - thanks - Joe
Fleet Owner
Joined: Apr 2008
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From: 0,0,1
Oil pumps have a pressure relief valve built in just in case there was ever a clog in the system. That 40 PSI, 60, PSI, etc. is the rating of that pressure relief valve and obviously the maximum oil pressure you will ever see with the pump.
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Cross-Country
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From: Pennslvania
Thank you for the response - so when they recommend putting in a higher rated oil pump besides the maximum pressure allowed by the pump I am assuming that the higher rated pump also delivers more oil to the engine - thanks - Joe
Post Fiend
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From: Waterloo, Iowa
Relief or bypass valve sends oil back to the sump, for example in cold weather when oil is thick and viscosity is high. Also at high RPM. High oil pressure is not necessarily a good thing, the oil flow is more important than pressure. If the relief valve sticks open due to varnish or gum then oil flow to critical parts will be insufficient, if it sticks closed excessive pressure can blow out the oil filter or even casting plugs in the heads.
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Higher rated as in higher volume not necessarily higher pressure.
Fleet Owner
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From: 0,0,1
A higher PSI pump does not necessarily deliver a higher volume of oil. A higher volume rated pump is only necessary when the engine is excessively worn or being used for racing.
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Cross-Country
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From: Pennslvania
I read that as long as you have the front cover off an 5.4 L 3 v engine you should change the stock oil pump and install a Melling 40 or 60 psi pump since the original Ford pump is marginal - just thinking ahead when I have to change the chains, tensioners, phasers etc. on my truck - thanks for the responses - Joe
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I have heard the factory pumps are MARGINAL in the strength of the pump cover plate. SOME have blown out or bent the cover and leak off pressure to sump... I think what they are saying is the factory pump is marginally acceptable and if you are rebuilding you can get a better QUALITY pump installed.... and probably get a little more flow and psi at the same time.
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From: Isanti, MN
I have heard the factory pumps are MARGINAL in the strength of the pump cover plate. SOME have blown out or bent the cover and leak off pressure to sump... I think what they are saying is the factory pump is marginally acceptable and if you are rebuilding you can get a better QUALITY pump installed.... and probably get a little more flow and psi at the same time.
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