Does this sound like a bad oil pump?
Does this sound like a bad oil pump? 
My car has a 40k shortblock in it, when the cam was put in a few years ago we also put new bearings and arp rod bolts. At hot idle i always have 40 psi, wot throttle about 65.
Yesterday driving around i was climbing through the RPMS oil pressure was going up just fine, when i came to the light at idle, the pressure dropped to about 10-15...
I pulled over, popped the hood, heard no noise what so ever. I shut the car off, let it cool, checked the oil. I was about half a quart low due to my valve guides being warn(stupid .641 lift cam
)Not thinking that was low enough to cause a problem, i started it back up...0 pressure, gauge did not even lift from 0, immediate lifter clack also. Shut it down after about 5 seconds.
So i called a flatbed and had it towed home. Its a 98 drivetrain and from what i gather it sounds like my pump puked.
Any opinions?
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I don't believe the pump is going to make pressure on minute and 0 the next. These pumps are just about bullet proof. Pull it apart and examine the guts. What is there to wear out or break? I guess it could get damaged if you don't change your oil and you let trash circulate through the system, but then other things are being damaged too at that point.
Well, i am open to other explanations or opinions. Odd how the car had tons of pressure then 0, i would think every bearing would have to check out at the exact same time to totally lost pressure all at one. I have lost a few motors in my time, even when the pressure is low, knocking, i had some oil at the top of the motor...I have NONE.
I guess the bypass relief valve is a pretty common failure point.
I guess the bypass relief valve is a pretty common failure point.
Well, i am open to other explanations or opinions. Odd how the car had tons of pressure then 0, i would think every bearing would have to check out at the exact same time to totally lost pressure all at one. I have lost a few motors in my time, even when the pressure is low, knocking, i had some oil at the top of the motor...I have NONE.
I guess the bypass relief valve is a pretty common failure point.
I guess the bypass relief valve is a pretty common failure point.
The good news is that the engine came back to life w/ a new pump and was still running track events a year later.
Fram Filters are about good to use as a spitoon and thats about it. I was gonna say the sending unit went out on you but it may be the pump. You said .641 lift cam so maybe it had a little valvetrain noise prior and you just didnt listen close enough because you had normal oil pressure at that time. Never hurts to check that though. Just an additional thought along with the o-ring and the pump itself.
In order for the bypass piston to get stuck OPEN several things have to happen first. The oil pressure has to increase to the point that it excedes the spring tension that's trying to hold the pistion in the CLOSED position. Once the pistion gets there an obstruction much be suddenly present to keep the bypass hole open. This burr or obstruction can not be present while the pistion is moving in the direction or the bypass hole of it might inhibit the pistion from traveling far enough for the bypass hole to open. The bypass hole shouldn't flow oil unless the oil pressure goes for some reason like the oil filter is never changed, but the oil filter has it's own bypass. That's a pretty heafty spring in the pump. I haven't measured it with a spring gauge, but it take substantial force to compress it and many people shim it to try and keep the bypass hole from opeing.
Well, it was the pump relief valve, i opened it up and the valve was stuck wide open, hit it with a screwdriver and it snapped shut.
New pump is in, i think i pinched or rolled the O ring though, gotta try again this morning.
New pump is in, i think i pinched or rolled the O ring though, gotta try again this morning.
I don't believe the pump is going to make pressure on minute and 0 the next. These pumps are just about bullet proof. Pull it apart and examine the guts. What is there to wear out or break? I guess it could get damaged if you don't change your oil and you let trash circulate through the system, but then other things are being damaged too at that point.
I dunno, all i know is the valve was open and that makes me happy.
