Oil Pressure Question

I had a mechanic do an oil presure test on my 96 Nissan Sentra 1.6 Liter engine (DOHC GA16DE). His oil pressure gauge read ZERO at hot idle, and only about 15 psi at 1500 to 2000 rpm.

There is a lot of valve clatter when the engine is warmed up.

Even so, when the engine is hot and idling and there is supposedlly ZERO oil pressure, if you remove the oil filler cap, plenty of tiny oil droplets spray out of the hole. Would this be happenning with ZERO oil pressure ? Seems like plenty of oil is still getting up to the top end, if it splashes out so well. What's going on? If oil is getting up to the top end, why is there so much valve clatter?

Thanks

If you have hydraulic lifters, they require a small amount of oil pressure at all times to keep from collapsing and clattering, as you have discovered.

If this is *after* replacing the OPRV it might be time to start looking for a good used engine...

nate

No shit? With 2 camshafts and 16 valves flying around in there what do you expect? The oil that is in there to stick to them like glue?

Have you done any work on the car recently that would cause you to suddenly ask the mechanic to do an oil pressure test?

This is a sign you don't have oil pressure.

You have residual oil up there, but there is no flow, because there is no oil pressure.

It is probably time to buy a new engine, although it won't hurt to drop the pan and check the oil pump. It's probably too late, though, if you have been driving it like this for any time at all.

--scott

Its dead, Jim.

The clearances in the bottom end of that engine are obviously so huge (worn out) that sufficient pressure can't build up. Note that zero PRESSURE does not equate to zero FLOW. The oil pump might be pushing gallons per minute through the engine, but if the clearances are too huge there won't be any back-pressure to show on the gauge.

As far as the cams still flinging oil at "zero" pressure, its probably got a fraction of a PSI and that's enough to push a little oil up there. But not enough to properly fill hydraulic lash adjusters. They require real pressure.

pressure at all times to keep from collapsing and clattering, as you have discovered.

If this is *after* replacing the OPRV it might be time to start looking

for a good used engine...

NEW? Not likely. What part of the country do you live in?

How did you get the regulator blocked? The loose screw didn't work....

I sure would be taking that oil filter mount off and be at least taking that in to get the valve put in if I couldn't figure it or didn't have the right tools. That would be a shit load cheaper than a remanufactured or rebuilt engine.

You can call the Dealer to get his price. I know Chrysler in Canada offers factory remanned engines at a competitive price.

Mike

I live in Pa.

I used a carefully formed sheet of aluminum foil to make a plug, with some excess coming out, so that it couldn't get sucked into the bypass hole, and not enough to block the flow of oil into the filter. The spring is still in the hole, which also prevented the foil plug from getting sucked in. I pushed the foil plug into the hole a bit, and pressed it in. During the test drive, the oil light came on, same as ever, and the clacking sounds were just the same. I removed the filter after the test drive, and the foil plug was still in the same place. I then removed it, so it couldn't come loose later.

Since there was no apparent improvement in oil pressure after blocking the bypass, it appears that the bypass is not dumping the oil back to the pan, but is sending it on into the head, or wherever the filtered oil goes. My oil press is still very low, even with the bypass plugged, and it seems like even if I spent $80 for the dealer to replace the oprv, it would never open at such low pressures, and would just act as a plug. I can plug it myself, and at least get the oil going thru the filter.

oprv or no oprv, the engine is hosed, due to wear, it seems, as so many people have said.

My last desperate attempt would be to drop the pan and check for sludge blocking the oil pickup screen or the pump. Or an oil pump bypass valve stuck open.

I've had several mechs listen to it, and have had various diagnoses. Bad oil pump, stretched chain, open clearances in the crank. One mech said the rods were fine, since he didn't hear that sort of noise. One mech said it just sounded like an old engine, and to put some stp in the oil.....

The engine has 177,000 miles on it. Oil and filter were changed every 5 to 7 K. Seems like sludge would not form under those conditions, unless antifreeze was leaking into the oil, but never was any indication of that. Never had the vanilla colored stuff in the oil. Maybe this engine just was destined not to last very long....

Do you have a personal web site? I wonder if you could throw up a pic of this OPRV, because depending on design, what you did may or may not have actually blocked the bypass passage.

nate