TheBruce

We had some debates a few months ago about what the correct hot idle oil pressure was. It was inconclusive. Some guys were 2-2.5, others were 1-1.5. Im the latter. If i'm running really hot my idle oil pressure will dip down to .9.

I ran across some posts in the 996 forum about this. It seems like a common issue for 996s but more extreme. Guys were reporting idle oil pressure of .3 or .5. The simple fix they described was changing your Oil Pressure Relied Spring and Piston. https://www.renntech.org/topic/39205...essure-solved/. It looks like in the 996 there was an issue with the spring breaking and the piston design itself (which was updated in the 997).

Anybody done this on a 997?? It looks like a 5 min job. The bolt holding the piston and spring is located right between the engine carrier and oil pan and I always wondered what that was.

Flat6 Innovations

We alter these in every engine we build. It does help oil pressure, BUT remember that oil pressure is resistance to flow more than anything. Engines that idle with less pressure, either have hotter oil, or more open clearances internally, or both. Viscosity index also plays a role, this is why you can't compare the oil pressure between different engines.

Iceter

How could altering your pressure relief valve help your idle oil pressure?

Common spring-actuated relief valves come into play at higher RPMs when the pump is spinning faster and delivering too much pressure. At low RPMs, the pump isn’t providing enough pressure to cause the valve to be actuated.

Does the Porsche pump or relief valve work differently than almost every oil pump in the industry?

Flat6 Innovations

But, the earlier version, or an engine with a weakened spring will pop off early, and can cause low pressure even at idle.

We see engines that run high oil temps are killing the relief spring pressure, and that sometimes keeps the bypass valve from sealing off, resulting in lower pressure at all times.

Remember, how things are supposed to work, is always trumped by the variables that determine how they actually do work. There are times where I omit the entire factory oil pressure relief system in these engines.

TheBruce

Jake you rock. By "alter" do you mean you replace them? And would you recommend replacing this as a general preventative measure? And does the M96/05 and M97/01 have the same design?

Iceter

Makes sense, thanks for explaining. But fixing a malfunctioning valve is different than modifying a functioning one. I would assume that a malfunctioning valve would cause low pressure across a wide band of RPMs, not just at idle.

So now I’m curious what the modification is that prevents this? I’m interested because today is the first time I’ve heard of this being a thing.

UGA AV8R

Anyone have a picture of what this looks like for the 996? Got the part in the mail today and just want to get an idea of what this looks like assembled before I change it. Also, can it be done with oil in the car? I just changed the oil a couple of weeks ago. Thanks!

Tj40

OK so maybe a dumb question but does the relief valve just restrict flow of the oil around the engine or does it 'short circuit' the normal oil flow path and just dump oil back into the sump?

If it is just a restriction to the oil flowing around the engine then simplistically a lower pressure at a given engine revs means more oil flow which I would assume is good as more oil is circulating and lubricating.

If it short circuits the oil flow path around the engine then higher pressure is good as the opposite is true as it means more flow is going around the engine for a fixed RPM.

The assumption seems to be the latter but it's always good to clarify ;-)

Mike Murphy

The spring valve is a bypass because the oil pump is a positive displacement pump. I believe it dumps directly back to the sump. There is also a bypass valve and spring in the oil filter on the m96. Same principle - too much pressure and it bypasses the filter, but the filter bypass goes to the engine internals. The filter bypass is there in case the filter gets clogged, so it’s a different reason, but the prevention is the same: too much pressure could break something, so it’s best to bypass than to break an oil pump or filter canister

Quadcammer

Its just a piston, a spring, and the threaded cap with a crush washer, in that order. You will lose roughly .5qt when you replace this. If you use a seriously clean drain container, then you can just pour the oil back in.

UGA AV8R

ok thanks. Pelican sent me a small, thick black rubber seal vs a metal crush washer. Sound right?

Flat6 Innovations

No.. Not at all.

UGA AV8R

I went back and looked on their website, and what I ordered in the picture looks nothing like what they sent me. Wouldn't be the first time they've sent me the wrong part. Calling them now.

Tj40

This explains it perfectly - Thanks!

Tipper

If I'm getting 4-5 consistently on the dash oil pressure gauge, is this normal?
Or too high?
2002 996.2 Carrera with just over 100,000 miles.