Oil and Oil Filters
Chevy Silverado
Mercury Cougar
Chevy Trailblazer

The oil pressure drops to 0 when hitting the brakes on my 95 cougar 4.6 v8.It goes back up when given gas again.why?

Answer

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Wiki User
02/21/2009

sounds like tired oil/ worn pump/ dirty filter/ ask yourself if you did your maintenance, if not bill has come due To be honest, Those are all very good reasons for why your Oil pressure drops down to 0 when your stepping on the brake, but the most commin reason for that is that when your stepping on the brake, your actually creating a "G" force that sends the oil in the Crank Case to the front of the car against the inside of the Oil pan. What this does in turn is not keep your oil pickup tube submerged, thus not allowing your oil to be "Sucked up" through the tube. This will instantly put air in the line creating a "0" reading for your Oil Pressure, when you come to a complete stop or when you are at cruizing speeds, the oil is leveled out pretty much allowing your oil pickup to remain submerged and keep a steady reading. This is why when you are at a stop or cruizing your Oil reading comes back instantly. You might ask, "then why doesn't it do the same thing when I accelerate hard, pushing the oil to the back of the pan and allowing the oil pickup tube to become UN-Submerged again, thus creating a "0" psi Oil pressure reading." Well, there is a good answer for this also, the reason for this is because is some cars the Oil Pickup Tube is actually located at the rear of the oil pan, so in return, when your jumping on the throttle hard, pushing the oil to the back of the pan, you are actually making the Oil Pickup Tube Super Submerged and maintaining your oil pressure. In most cases the oil pressure will remain around 60-80psi depending on throttle position in most cases. The easiest fix for this problem would to be: A... Check to make sure your Oil Level is where it is supposed to be. B... Add Oil to the engine even if it is at its optimal level, not more than a quart tho, just enough to top it off and keep that little extra oil in the pan to maintain the proper reading. This issue MUST be fixed or you risk the option of possibly RUINING YOUR ENGINE BY BLOWING IT UP. An engine that lacks Oil Pressure Often will brake a piston connecting rod, damage the piston itself, ruin the crank bearing, ruin the top end bearings/seals/and any parts that rely on oil to keep them lubricated enough to reduce friction to the point of avoiding overheating and scarring of the metal surfaces. Hope this helps you and anyone else out as much as possible! I have been in the Automotive repair field for a while now and have come across MANY oil issues so you have good reason to trust my "Words Of Wisdom". : )