Low oil pressure under load

I have a 2000 996, at start up and hot idle oil pressure is good. 5 bar cold 1 bar hot idle. When not under a load At high rpm oil pressure jumps to 4bars, but when under a load it dips from 2 bar abit and recovers to 2.5. During spirited driving car develops an tick I�m assuming from lack of oil pressure. Upon returning to regular driving Tick eventually disappears. This is my first 911 any help would be appreciated.

First thing I would do is replace the oil pressure relief valve and spring with the upgraded one. What type of oil/weight are you running? What type of filter?

Porsche OEM filter and I have tried different oil weights. 0-40, 5-40 and 5-50 really no change. Oil sump is clean.

At what RPM range are you are you reading the low pressure?

At 3500 when not under a load it reads 4+ bars under a load at 3500 2 bars.

Ordered relief valve parts from pelican. Will change out next week and see what happens. It�s cheap if nothing else preventative maintenance.

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If no change replace the oil pressure sending unit at top of the cam cover, known to be unreliable at this age.

I have seen a lot of that on different forums, however the tick that comes with the lack of pressure has me thinking it not the guage or sending unit.

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Probably a unrelated issue caused by dirty / sticking lifters caused by dirty oil. Once you do the previous parts swaps change oil with DT40 & go out for a long spirited drive. That should help but may have to replace lifters that are clogged.

I had planned on giving the DT 40 a go. Will update when parts come In.

No results, still the same. At high rpm under load tick developed then after a few min returns to normal. Sound like I�m starving heads for oil at high rpm to me. Could the gears just be worn in the oil pump?

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The only thing I can think that would cause low pressure under load is crankshaft play being too high. Perhaps it�s the trust bearing or main bearings. What happens is that under load, the crankshaft pushes forward or back and because there�s too much play, oil escapes easily past the main bearings - it flows out way too much because the clearances are too great - which lowers your oil pressure and essentially starts to starve the engine of lubrication, which is why you are hearing the ticking sound. I guess it�s also possible that oil is escaping somewhere else on the valvetrain area that�s causing the issue. Either way, it doesn�t look good.

It's really odd having a load based oil pressure drop on these engines. They are an RPM based system with effects from temperature, RPM , and viscosity. Load does effect the temperature, but is progressive and not instantaneous. I know you have checked the oil filter for collapse since you have tried different weight oils, but I can't think of anything else that would be suspect. If the load causes an instantaneous drop, it would seem to be the mechanical stress is causing an internal oil leak? So, you are cruising at 3500 RPM in 3rd gear , and press the throttle to the floor and the pressure immediately drops 2 bar from it's cruising pressure? Interesting !!

When cursing at 2500-3k and floor it, I get a slight drop maybe a1/4 bar then it will hit about 2.5-3 bars. When I let off it will jump to 3 -3.5 and drop back to 2 2.5.

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I would suggest for a positive diagnosis that you install a manual pressure gauge, and route it temporarily so you can monitor while driving..The OEM gauge is notoriously inaccurate and can even fluctuate due to voltage changes, ie under load.... I understand your concern with the resulting ticking sound that seems to result from the pressure drop, but it is entirely possible ( although unlikely) that you are dealing with two separate problems.

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I don't get that last part of that last sentence. I get the first part. Low load, low RPM = decent pressure. As soon as you put load on the engine, it drops. We don't have to worry about temperature and pressure due to RPM, the oil pump gears, being a positive displacement pump, aeration, etc. So that's not it. When the engine is loaded, the pistons push much harder on the rod bearings and the crankshaft will be forced horizontally trying to force the oil out of the bearings. It cannot be forced out easily because oil (liquid) cannot be compressed, but it can be pushed except that it's too viscous. However, if there's an opening due to crank end play or a failed bearing coming apart or separating, then the oil flows freely and the pressure will drop. By the way, the fact that you are hearing a ticking sound could mean that you are actually losing a LOT more pressure than the oil gauge is reading. The gauge, even if the pressure is zero, will not drop to zero right away. When you let off, the end play or separation closes up, and oil pressure increases again. That last part of your sentence of dropping again, I"m not sure about this... I would have your car checked out at this point, as it's possible you could be doing some damage.

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I'd second a collapsed or dirty filter. I've seen these symptoms from a bad filter before. I have also seen this from a plugged oil intake screen in the sump where sealant has blocked it. If the pressure relief spring and piston haven't been changed, I'd do that.

About two months ago I looked for information on Rennlist for exactly these symptoms on my MY2000 911(76K miles) - oil pressure drop, and a ticking sound after spirited driving. My independent down here on the Eastern Shore of MD, Chadderton Services, figured out the problem: a clogged oil pickup tube and screen. My shop pulled the pan, replaced the oil pickup tube and screen, updated the pressure valve, purged the system with Rislone, changed the oil and filter twice, and did an oil analysis. A ton of plastic was clogging up the oil return in the sump and causing starvation a high RPM and load. I had previously replaced all of the ramps, pads and chains at 65K miles but I don't think my previous service provider carefully flushed out all the plastic debris left behind by some of these parts. The problem is now gone and the oil analysis found very little metallic debris so hopefully I have avoided major damage. My recommendation would be to drop the pan and pull the oil pickup tube soon and drive gently until you do.

I am chasing the same problem here. But on the highway on fifth or sixth gear, if I steer quickly to avoid an obstacle, the pressure drop about a bar lower than what is is normally and slowly recovery to 3.5 bar. Like if it was oil starvation problem but It is my daily drive and I never track the car and I am coasting at 100km per hour. I change the relief pressure valve, the spring, the plug, the oil filter housing and I open the oil pan to look at the baffle and I change it. Fresh oil with only 3000Km on it, mobil one 0W40, level is good, new oil filter, only a piece of metal was stuck on the oil pick up tube after the screen which is not good... Is it coming from the oil pump or does it fall from the engine to the sump and being suck by the oil pump? I have to open the oil pump to see if it is coming from the oil pump...Ticking sound after a drive but nothing at start up... Oil pressure was good in the spec provide by Porsche at 1000, 2000, 3000, 5000 rpm and oil temperature at 90'C with my digital gauge plug into the port of the oil sending unit in my garage. New oil pressure sending unit too. So the only difference between is the engine under load and the car is moving. I took A sample to have it analyse, It came out bad with the PQI at 120 which is particules count. I change the oil three time a year at every 5000km or 6 months. The oil filter is cut open every 5000 km to be inspected and this time, I found more metal and black particules than before.The oil has always being analyse by caterpillar in montreal and everytime it came out green but not this time. A high amount of metal particule bigger than 10 micron. So I am not driving the car until I found the problem. I have to dig deeper into the engine. Next stop. The oil pump. Keep us post on what was your issue because some of us seem to have similar problem as your.

https://youtu.be/6tdplTKCWnw is this what you're all talking about?

Yes, kind of. That's why I am suspecting the oil pump.

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Would you mind posting the UOA so I can see the composition of the wear metals?

The bad analysis are the ones with the arrow next to the lines. Of course, it gonna help everybody here.

This is a fairly scary UOA report, and I say that because the wear metal levels are extremely low coupled with high PQ results. This indicates large wear particles. Used oil analysis can only detect wear metal particles that are 10 microns or smaller (some test methods can only detect wear metal particles 5 micron or smaller). The PQ results indicate high concentrations of particles greater than 10 microns. I see that the October 2017 sample indicated water contamination. Did the ticking/tapping sound and low oil pressure problem begin after that? Lake Speed Jr Certified Lubrication Specialist / Oil Monitoring Analyst LN Engineering Development Partner

If I remeber correctly, at this time in october 2017, everything was fine except for some moisture build up in the oil filling tube and under the cap. No oil pressure problem, no ticking sound and No oil to coolant intermix... I put 1000 km on the new oil after this just before storing the car for the winter.

Ok, The drop in wear metals is a warning sign. If I'm getting this right, the engine was fine prior to going into Winter storage in late 2017. Sometime after that, it began having the low oil pressure problem and the ticking. The subsequent oil samples showed low levels of wear metals (Iron, Aluminum, etc...) but increasing levels of particulate. The drop in wear metals and increase in particulates indicates the size of the wear debris has grown beyond 10 microns in size. The wear metal tests that show how much Iron, Aluminum, etc... can only detect particles smaller than 10 microns. The particle counts can detect particles larger than 10 microns, but it does not discriminate between alloys. The bottom line is that the analysis history indicates increased wear in your engine, and you are seeing the effects of that increased wear in the ticking and low oil pressure. I would recommend considering an engine rebuild as a preventative action. If left unchecked, it is likely the wear will continue to increase until the engine fails. Lake Speed Jr Certified Lubrication Specialist / Oil Monitoring Analyst LN Engineering Development Partner