Oil Pressure at Start Up

First post. I've searched, but not found this exact topic. I have read about other pressure issues but not this one. Sorry if this is redundant, just point me in the right direction and I'll go read some more. Q: How long should it take for the gauge to register pressure after startup? My 96k '04 Manual C2 All stock DD year 'round in Wisconsin, 5W-40 Amsoil, does the following: Approx 0 deg F start, it takes 10 seconds or a bit more for the needle to swing up. A couple of times the Low Pres warning message appeared. At cold key-on, prior to start, the needle sits at about 1 bar. Before the needle swings up, it fluctuates around 1 bar a bit. Today, 15F, ~ 8 seconds. In garage at ~30F, 2 or 3 seconds. Warmed up, 3000 in 5th, about 4 bar. Cold idle after winter start, about 4 bar. Hot idle after driving 45 minutes to work, 2 bar or slightly below. I've never seen less than 1.5. The running pressures seem fine to me, but the delay in building pressure when cold is worrisome. (Yes, an accumulator system suddenly seems like a great investment.) I will plug in my OBD reader tomorrow and see what I get. Q2: Where is the pressure sender located schematically? Q3: Has anyone else noticed this behavior at starts below freezing? Q4: Does anyone have experience of this being an early warning of something serious about to happen? Thanks for your input, Jim in Green Bay.

Probably would be a good idea to change the oil pressure sender. It is located on the passenger side back between the intake runners. Accessible from underneath with a crow's foot wrench. Undo the wires from the top, remove right rear wheel, look up and you will see it. You can check for any CEL codes, but those are emissions related and will not show anything about oil pressure.

Second thing to do is change out the oil pressure relief valve and spring with the updated version. It is a simple job. You need #5, 23 and 24 here http://www.autoatlanta.com/porsche-p...section=104-00

Third thing to check is the bypass valve in the oil filter canister. Better than checking it is to buy a new canister and filter. Porsche sells them together now for less than $30. Or spring for the LN spin on oil filter adapter and use the no bypass oil filter they supply.

All good suggestions by Joe. How old is the oil? You may want to check if your oil filter has collapsed. Also consider switching to Mobil 1 0w-40 for the winter. You would rather have oil than no oil pressure at the first 10s of engine start. So bad for the engine...

I had weird oil pressure readings, changed the sender and all went to normal. After, I also changed to the LN spin on filter, but for other reasons.

Thanks for the info, esp Joe - the sensor instructions and pic. I already have the LN Adapter. Using a Bosch 3332. I also see that my spare filters that I got from the selling indy dealer are Bosch 72233WS. Honestly, I don't know the difference there. Please educate me on the technical reason for a no-bypass filter. Doesn't it risk lack of flow in cold situations where extra pressure is required to push the oil through the media? So, can anyone tell me how many seconds it takes your car to show significant pressure after a cold start? Thanks again. I'm ordering the parts tonight and will install everything and report back ASAP. Jim

Even at 30F, you should get the full 5bar almost the instant the engine fires up. 2-3s is definitely not normal.

Yep. 5 bar after a second upon startup.

Jim, Funny you post that, because I just went through the same EXACT scenario as you, a couple of weeks ago. My original post is below. For me, car was fine but I needed a new Variocam Solenoid. Dropped it off to get replaced. A couple of days later, i noticed the Oil Pressure warning light was staying on longer than the other lights did, at startup. The oil pressure would be at zero and would take about 5 seconds before it began to rise. It would then get up to about 3 on cold startup, which is too low. It should be closer to 5. After the car was driven, it would build pressure as normal, at startup, but still would not get about 3. Mechanic replaced the sensor unit, which seems to fix this issue 90% of the time. For me, it did not. After some research, I had a thought that they may have used too much sealant when they replaced my cam cover after fixing my actuator. This causes an issue because the excess can break off and clog the oil pickup tube. My next move was to change the oil, drop the oil pan (very easy to do), and see what was up. I also replaced the oil pressure relief valve and cylinder, which costs about $20 and is extremely easy to do. The relief valve looked ok, but i installed the new one anyways. My oil filter tube had some pieces of sealant stuck in the screen. I cleaned that out, replaced the oil pan and oil filter. After filling with oil, i started her up and everything was back to normal. You could replace the sensor, which is a $100 part and about 1 hours labor, and see if that fixes the issue, but it doesn't seem like that's your problem....Usually the pressure is much more erratic if the sensor is faulty. My recommendation is to drain all of the oil, drop the pan, and look for any pieces of crud at the bottom of the pan...clean all of that out. Then, look up and you'll see the oil pickup screen and see if there's anything stuck to the screen. If there is, you prob found your culprit. When reinstalling the pan, make sure you use a razorblade to remove any of the old sealant. When resealing, only use a very thin bead, or else youll be in the same boat as you are now, when the excess comes off and gets clogged up. Hope this helps! I was very frustrated at the time and worried about something major going on. I'm glad it was a simple fix, after some trial and error. If you have any questions you can message me privately. Jay https://rennlist.com/forums/996-foru...t-startup.html

I get 5 bar within 1 sec of start up. Then once its up to operating oil temps i get 2 bar at idle and 4 to 5 bar while driving.

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I don't recommend this, as it will worsen his problem, not alleviate it. At low startup temperatures you're better off with the larger stock filter media (including the bypass-valve) than with the spin-on filter which is considerably smaller and hampers initial flow. No oil at all is a *lot* worse than contaminated oil, hence the bypass valve in the stock setup. A no-bypass filter 'upgrade' would elongate the time it takes to build pressure and actually put his engine at considerable risk. That said, with the stock canister it should not take 10 seconds for the oil-pressure to register, although OP mentions he is running the spin-on with another filter. Does that filter have a bypass valve? If so, then your issue lies elsewhere, such as the screen from the pickup-coil. It should read straight 5bar when cold at all RPM.

Guys, Thanks a ton for your posts. Parts are supposed to arrive Thurs and I plan to have my new lift (!) operating this weekend, so the 996 will be the first car I don't have to lay on my back to work under. Yea! (Only been waiting about 20 years for this day to arrive...) This car had a string of owners before I purchased it at 68k almost two years ago. I've already put 30k on it, and it's been rock solid. Surely if there was something wrong with the cam solenoid operation, it would set a code, no? The indy dealer that I bought it from was great. Clutch verified nearly new, IMS replaced (was already a LN in there), AOS, RMS, (all the acronyms!), compression and cam angle checked good, very few overrevs, etc. So, certainly the pan could have been off in the past, but not recently. I have no problem to pull it off and have a look. Let's see what the weekend brings. At least the darn weather is warming up. Yesterday it was -13 on the way in. So, the pan does not use a gasket? Jay, what sort of sealant did you use? Jim

Hey Jim, Yes, I did get a check engine code for the cam solenoid. I don't remember the code off the top of my head. This had nothing to do with my oil pressure situation, but I believe when my Indy resealed the cam cover, it either wasn't sealed 100% correctly, or they put too much sealant. I'm not aware of the brand they used as the sealant. This isn't something i was comfortable doing myself. For the oil pan, it's very simple to remove. it's a bunch of small bolts. There's no gasket. Just be sure to clean the surface area of any crud from the old sealant that was used before you re-apply. I used Loctite when i resealed, although i'm getting some oil drips around the edges. I'm in New England and it's very cold, so I don't know if it fully cured overnight before I refilled the oil the next day. I'm going to do it again in a couple weeks and get a different sealant. I have the name somewhere, but it's the one that LN recommends to use and other people have also mentioned it. When I remember the name, i'll let you know.

Use Dreibond. Apply no more than 1mm bead and smear it flat with your finger. Jakhe has a diy video on you tube for this.

Drei Bond 1209, Loctite 5900, Loctite 5920, all are excellent gasket makers and have been prescribed by OEM's BMW , Audi and Porsche. As mentioned avoid excess "squeeze out" by using sparingly.

I've always heard...apply the Drei Bond and reinstall the oil pan. Wait 24 hours before putting oil back in the sump. Longer if it is cold in the garage (or driveway).

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That's right. Jake tried all that were mentioned by Porschetech3 but is reco was still the Drei bond because it works well and it's easy to clean up e.g. the next time you need to open up the oil pan and remove the old sealant.

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I hate to disagree with Jake, but I prefer the Loctite 5900. Drei Bond 1209 was prescribed by Porsche for the Cayenne and I found that it doesn't stick (***** up) unless the surface is 100% clean and dry which is not always possible when on oil pans/valve covers when oil is dripping for days. Loctite 5900 will stick even when less than perfect dryness on work surfaces. Both have similar "tack free" times for assembling the mating surfaces. Drei Bond 1209 full cure in 24hrs, while Loctite 5900 full cure in 21 days but can be filled with oil after 30 min with a gap thickness of 0.5mm, and has a blow out psi of 175psi after 7 days at 0.5mm gap thickness. But all are good if used in 100% clean and dry environment . Loctite 5920 is silmilar to 5900 but is a bit thicker and can seal wider gaps.

Wait...ummm...none of this answers the question of "what type of oil should I refill with?"

^That's good info and good practical tip. I have had no problems with Drei bond but then I always keep the mating surfaces spotless and smooth.

Guys, First, thanks for the sealant info. Always good to get recommendations. (I used 1207b - have had success on bike engines with it.) OK, I've done some work, but it's not lookin' good so far: Step 1: The pressure gauge needle was erratic, so I changed the pressure sensor. It now displays a steady 0 bar at key-on. (The old one fluctuated around 1 bar at key-on) It swings up to idle pressure very smoothly (the old one jerked upwards). So, I surmise that the old sensor had some stickiness and the new one seems to electrically work as expected. However, the bad news is the pressure reads lower now. At 3000 rpm warmed up cruise, it's 2.5~2.7bar. Cold idle at 2~3 bar, and hot idle at 1.0 bar. This is 1 to 1.5 less than a month ago. (Is it possible to get the wrong sensor and be mis-calibrated?) Also, it still takes 10 seconds to register pressure. Step 2: The following evening, I changed the relief valve spring and piston. All parts from Pelican. Then I removed the oil pan. The strainer was perfectly clean. In the bottom of the pan there were a couple little clumps of sealant and a fingernail shaped/sized piece of hard plastic or resin. Brown. There were small amounts of sealant squeezed out of the joint, but still attached. I cleaned it all up thoroughly and reassembled. Result: No change whatsoever. So, I'm getting nervous here. Something is obviously wrong. This is my daily driver. I've been driving this car for 30k over less than 2 years with rock solid 4 bar cruising pressure until recently. 97k total miles. It runs like a top. The oil looks perfect. Deep amber and visually clear, no specks, no sheen. My magnetic oil plug had a smudge of grime on it. Seems normal as I've not had one be perfectly clean after decent mileage. I've not done an analysis. I have pics of all the above, but I'm sure you guys visualize this description. Ideas? Jim in Green Bay.

Did you change the oil and oil filter?

Use a manual gauge to test the oil pressure. You can use the port on the other head for this and leave the sender in place. If the pressure is still low or takes 10 seconds to respond, you will know you have an engine problem.

Thanks Tech3. Yup, I agree that's what I need to do next. The heads are a common casting, right? That means this tap is on the bottom towards the rear on the left side head, right?

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Yes it is common casting, but it means the port is on the left rear instead of right front ,but it is still on top...

Of course. A little late night brain fade there. Maybe it was wishful thinking that it would be easy to access...

It seems like every pressure sender you install may read a bit different. I went through several. Check against a manual gauge if possible. When I was chasing some random issues I also had read that if the needle moves up in the 'key on' position it could be a sender or a gauge cluster. I was also having issues (so I thought) with my fuel gauge needle. Turns out it was my sending unit... I verified that by hooking up a different cluster.

Guys, I should maybe leave this subject alone, but my curiosity has not been satisfied. Good news: the long delay in building pressure at cold start is "fixed". Bad news: I left that word in quotes because I don't understand why. Here is a high level summary: Problem: Oil pressure takes 10 seconds to build after a cold start. Step 1: Changed sending unit. Result: Gauge display now at zero when cranking, smoother operation. 10 sec delay remains. Sender failure mode matches common descriptions. Step 2: Changed the relief piston and spring for the new chamfered 997 design. Result: No change at all. 10 sec delay remains. Step 3: Inspected the sump area. Result: No debris found, screen was clear. 10 sec delay remains. Step 4: Unrelated? Changed the oil fill pipe to the 997 one. Had a crack that I had sealed. Result: 10 sec delay remains. Step 5: Measured pressure with mechanical gauge at same point as the dashboard sender. Result: Pressure read exactly same as dashboard gauge. 10 sec delay remains. Step 6: Inspected sump area again. (PCA advice about potentially leaking suction pipe, etc) Result: Pipes all intact, seals good. No debris. Step 7: Inspected oil pump internals. Result: Slight scoring on left side of housing. See pic. Gears fine, hex shaft fine. Axle fits feel fine. Step 8: Inspected scavenge pump on right side head. Result: Spotlessly clean, spins tight and smooth. Step 9: New oil (Amsoil 5/40) and Bosch spin on filter (LN Adapter has been in place all along). Result: Problem fixed . Pressure builds immediately to 4.8 at cold start, responsive to RPM, hot idle = 1.3 Step 10: Cut old filter apart. Result: Looks perfect. No particles, seal intact, no debris. See pic. Conclusion: Something about that filter was causing a 10 sec delay in pressure, and a RPM pull down when the pressure finally built? Why? How? Also: Since the oil relief function is a separate spring and piston, I don't think it really matters if the filter has a relief or not. If it doesn't, the external relief provides the function and pressure will be limited to the spring preload force. If the filter does have one, the pressure will be limited to whichever comes first, the external spring or the filter's internal spring. Either way the function is provided and any filter is going to have a relief pressure set point that is adequately high. My cut-open Bosch filter does not have a relief function. I do note that the media pack is separate from the steel end cap on the entry end of the filter. I'm assuming this is normal since there is no glue on that end, and on the bottom of the filter there is a big-*** leaf spring pressing everything together. The anti drainback seal (red) looks fine. No debris, no apparent damage, still flexible. Sorry about the big pic. Not sure how to manage the image size here. Separate question: Any engine rebuilders out there that could give an opinion about this oil pump housing wear? The scratches are 1 to 2 thou deep in my opinion. They look bad, but can just feel them with a fingernail. What are the horizontal witness marks from? Does this indicate a need to replace $$ the oil pump housing? If so, can you point me to any instruction write-ups? Guys, thanks a ton for your expertise. I have not found an answer to the pressure build delay and I think the community needs one. They made a lot of these engines. There is no way this is a unique failure mode. I'm glad the car is back to normal, but Why, why why? Jim in Green Bay.

You had a restriction in that filter somewhere. Cut the end caps off and spread out the pleats to see what you find in there. Good news that the fix was simple even though the diagnostic process was not quite as simple.

Are you losing coolant?

Coolant: Not that I'm aware of.

I agree with Ahsai, check for coolant contamination of your used oil. Something has caused the filter to not flow oil. The big leaf spring is actually a by-pass spring that when the filter will not flow oil fast enough, it will deflect and let oil by-pass the filter media. Some filter medias as very susceptible to coolant . Most oil filters today are a synthetic or synthetic blend and some glass fiber/resin, but there are still traditional cellulose (paper) ones in the market also that will bind-off is coolant is presented.

Hmm. Good info. You mean like a Blackstone analysis? Visually, there is no phase separation after sitting in a glass jar. Tell me more about how that spring works. What creates the force downward on the spring? So how does our hypothesis work? Filter media is clogged lets say. Oil press in front of the filter quickly pops open the relief valve and flow proceeds to the engine bypassing the filter. The pressure sender registers the pressure at it's location - that is, the flow restriction in the system of everything downstream of it's location. Hence, the only way to have a zero reading at the sender for 10 seconds is to have basically zero flow past the sender. That means the oil is not getting to through the relief valve (which was brand new and verified to move freely in it's bore) or after the relief valve it would need to be short circuiting back to the sump without reaching the pressure sender. I'm not at all discounting what you're saying, and the evidence is that there was something wrong with the filter, but I'm trying to figure it out schematically. Any advice about the pump housing?

Please confirm what filter was in place when you had the oil pressure issue.

Bosch 3332.

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Stay away from these, and K&N Filters. I did all the development work for the LN SPOFA based around the Napa Gold filters made by Wix. These simply cannot be beaten, and they never give pressure issues like you have experienced. The Napa Gold sounds like a generic filter, where K&N sounds all fancy. We continually cut apart new filters to e how they change, the Wix never changes, and hasn�t in over a decade of use with the SPOFA. Stick with Wix and you�ll use the SPOFA as it was developed.

Problem did not exhibit itself until I had +/- 4 or 5k miles on the oil/filter. It is a DD, and I drove it straight through the Green Bay winter. It occasionally did cold starts after work at -10, -20F. Oil is Amsoil Euro 5/40. Symptoms were not present during the cold part of the winter but were shortly after.

Flat6, Awesome and I appreciate your input here and general support of the forum. Can you walk me through the cause of the failure?

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Yeah.. The filter sucks. On top of that, in your environment a 0/40 oil would be a better fit in those temperatures. The 5/40 just made things worse. Amsoil also has a tendency to have a heavier pour rate, which also doesn�t help.

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Yes, send the sample of the oil that was in the car when for the 3-4k miles prier to the filter binding-off, or test it with some "chem-strips" for testing for coolant. Blackstone or any UOA company do this. Sorry, I was mistaken about that by-pass, that particular Bosch 3332 does not have an internal by-pass , I was fooled by the hole in the "leaf spring", it looked like there was a by-pass behind that hole, possibly uses the same "leaf spring" assembly as the ones with by-pass. So, with no by-pass, you are literally waiting for enough oil to pass through the filter and fill the system before it can build any pressure, and if the filter is clogged from dirt, bound-off by coolant contamination, or just a s**ty filter as Jake says, you were waiting 10 seconds. Here is a link to the test strips, it says for ATF, but works for engine oil also, handy to have for quick results, but just for one use not much less than an UOA.. chem-strip

Mr Tech, Thanks.

Wait, so I have to let loctite 5900 cure for 21 days prior to driving the vehicle? Im going to use this on my cayenne valve cover job, its just in 4 small gaps spots, but maybe I should go with dreibond 1209? I want to drive the car after 24hrs at least.

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Of course not, if that were the case professional mechanics would never be able to make a living due to waiting on gasket maker to dry....and they would never use it...lol It depends on the thickness of the bond... If very thin as most joints are ( less than .5mm) It must be assembled in 10-20 min and it can be put in service in a couple of hours...The thicker the gap the longer it takes, Loctite 5900 will cure to a depth of 10mm in 21 days...( full cure) .... https://www.grainger.com/ec/pdf/Loct...Data-Sheet.pdf

If your DIY at home, letting it sit overnight before operating isn't a "bad thing" I try and start a lot of these kind of tasks on a day when I can let things sit.. Had to jump in on the Jurassic thread...

Resurrecting this thread back from the past as I have almost the identical problem. Start the engine at cold, the oil light comes on and the oil pressure needle sits at zero for a few seconds, then slowly comes up to about three. After a bit of driving oil pressure comes up a little bit to somewhere between three and four but never gets higher than that. Before this happened my car behaved the way everybody else describes it, which is it would shoot up to five immediately on start. I�m wondering if it�s a bad oil pressure sending unit. And if so, is it safe to drive around until I get a new one.

Well, you already have my experience. Two issues compounded. (Always a pain to diagnose when that happens.) Bad pressure sensor and bad filter. With my new sensor and Napa Gold filters, I am still driving my car years later without issue. The best diagnostic thing I did was to hook up a manual pressure gauge and confirm the pressure was actually ok. That gave me peace of mind. - Jim, thread originator.

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Thanks! Dumb question, how do you manually test the oil pressure?

It's earlier in the thread. There is a port on the top of left cylinder head.