oil pressure gained pressure??

[sick GN]

Was just cruising in the car the other day was just doing a little testing... trying to set the most controller... things were fine... after a run was up to 19 pounds of boost... let off and it backfired... died out and didn't start... reset the computer and it fired up just fine... while driving back home I noticed that oil pressure was up ten pounds at idle from normal... checked the oil and it looks ok... checked the antifreeze and that looked ok too... what could cause this? No knocking or anything from the engine

Thanks
Jeremy

 

[turbo nasty]

Not normal....

 

[sick GN]

I know it's not normal... my question for this part tho is what can make the oil pressure go up?

 

[getdowngranny]

What kind of oil pressure guage is on the car (electrical/mechanical)? I wouls try another known good or new oil pressure guage first to see if thats the problem. If the problem stays, them you have some gremlins to chase. Who built the front cover/oil pump? Is the oil pump fitted to be adjustable? What kind/brand of oil filter? What weight/brand of oil?

 

[earlbrown]

I wonder if your oil filter fell apart inside and now flows better?


My more experienced guess would be an electrical gauge that is reporting different.

Both are kinda screwey, but that's an odd happenstance. (at least it's not reading a drop of 10PSI at idle!!)

 

[sick GN]

Mechanical auto meter gauge... 20w/50 oil... I'll change the oil filter... otherwise it's a stock front cover and oil pump... 120k miles on it... where can I look to possibly chase down what could cause this?

 

[earlbrown]

cut open your filter and see what it looks like. No point racking your brain when that test is easy. What filter was on the car when this happened?

 

[sick GN]

Pf47

 

[dartguy340]

I wonder if your oil filter fell apart inside and now flows better?


My more experienced guess would be an electrical gauge that is reporting different.

Both are kinda screwey, but that's an odd happenstance. (at least it's not reading a drop of 10PSI at idle!!)

If it was flowing better the pressure would be lower. If the oil filter fell apart and something was blocking a port the pressure would go up because it is restricted.

 

[pacecarta]

a spun bearing can cause an oil pressure rise

 

[earlbrown]

with any luck a spun main would show a sign in the filter innards too. Hopefully that's not it as that's a yucky repair problem!

 

[sick GN]

Hmmm the engine sounded fine... I guess I can drain the oil and check for shavings

 

[sick GN]

Which oil filter would be best choice? I heard some actually do raise idle oil pressure

 

[dartguy340]

I don't know how a spun bearing could cause a rise in oil pressure. The oil pump itself does not create pressure. It produces flow and the resistance to that flow produces pressure. Resistance is created by the passage ways in the block through which the oil flows, and the amount of clearance between the bearings journals. As the bearings wear, clearances increase, allowing increased flow which reduces pressure. That being said, a motor put together with loose tolerances between the bearings and crank, ie: .004-.006 compared to one built with .002-.004 clearance, would have lower oil pressure. The tighter the clearances, the higher the pressure.

 

[dartguy340]

Mechanical auto meter gauge... 20w/50 oil... I'll change the oil filter... otherwise it's a stock front cover and oil pump... 120k miles on it... where can I look to possibly chase down what could cause this?

Seeing as how it is a mechanical gauge, check to see if somewhere in the line it got pinched or crimped.

 

[earlbrown]

Oil pressure is the balance of what the pump is putting out minus what the engine is hemorrhaging. If a main bearing rotates it closes off 1/5th of the bottom end oil flow.

Sick GN, and oil filter can't raise oil pressure... but a good oil filter will cost you less pressure drop. The relief springs in the filter adapter sets the stage as far as pressure goes. Everytime the oil has to go through a pressure drop, the PSI on the other side of that restriction will be lower.

Lets say you have a pump that's putting out 100PSI and you have a Fram filter that's causing 20PSI pressure drop... You'll have 80 coming out of the filter. (exaggerated even numbers). If you pop that Fram off and put a filter in that only has 10PSI of drop, you now have 90 at the gauges sending unit.


Good filters are Pure One (not plain puralotors), Mobil1, Wix, Baldwin, NAPA Gold. If you get the biggie oil filter kit, you can have a quality filter with less pressure drop to to having extra media in the can.

 

[sick GN]

Thanks earl! The idea was somewhat right lol... can I ask why you think a main is spun? Versus a rod?? I have had a rod bearing skin before... not on this motor tho... but when that happened the motor was knocking afterwards and toot can tell something was wrong... this time the engine seems to run fine... doesn't get hot or anything... I guess the only way to really make sure tho is to pull the pan right??

 

[earlbrown]

When a rod spins, it usually spins like a top, clearances open up, and then that horrible 'rod knock' sound comes out.

If you get a hiccup with oil pressure or some other anomaly that causes metal-to-metal on a main, it can shift just enough to cover the hole, or smear the bearing over the hole effectively plugging it.

I don't suspect that's what happened in your case 100%... It's just one way that oil pressure can go up (when it's not a gauge problem)


Have you opened up the filter yet? or stuck a 2nd pressure gauge on the engine?