Low oil pressure, aos?

[Punkd]

Long story short, I got a 01 996 c2 last summer and I still havnt been able to drive it. When I first got it, I noticed the oil pressure was ridiculously low but people told me it was normal as long as the light didn't turn on. (The light only turns on when it's almost at 0 which doesn't sound right at all).I drove it for about a month and my engine siezed. I had a spun bearing. Had the engine take apart bearings changed along with a standard rebuild and they told me bad bearings were the reason oil pressure was low. Now I have my car back and I still have low oil pressure. Here's what I've changed so far:

Bearings

Pressure relief spring and piston

2 AoS separator (the first one failed because idiot left the oil cap off with the car started, the second time it was because I thought i might have gotten a bad aos causing the oil pressure problem)

Oil filter

10w-50 synthetic oil

My check engine light also keeps coming up, secondary air injection system p0410. I have a feeling they messed up with the vacuum lines. Now here's the interesting part. When I opened up the aos line that goes to the throttle body, I noticed it was quite oily, but I can't possibly have 2 defective aos, can I? I eliminated the oil pressure gauge due to the fact that pressure was so low it spun bearings. Any information could help.

Thank you

[xmac]

Clearly, you were aware that there were problems when you bought it. You have way too any variables and history in this engine to figure this out quickly or even at all. A few things come to mind:

1. The AOS is taking oil vapors out of the crankcase gases, not a significant amount of oil should be going through it. It is normal to have some oil there, although it sounds like you have not run the engine much. Just to be clear, did you replace it with a new one?

2. Too much sealant used when engine was rebuilt and oil sump pickup is clogged ($14 for Loctite 5900 sealant)

Remove oil pan after draining the oil and visually inspect pickup for debris and any other debris in the pan. Use a light amount of sealant when re-installing and let it cure for at least 24 hours before refilling with oil.

3. Remove and cut the oil filter open to look for clues as to what type, if any, debris is inside your engine

report back

[Punkd]

Yes both times I purchased new aos. I'll take the sump off today. Is there anything in specific I should be looking for? Also is it possible to remove the oil pickup tube to clean the filter screen better?

Also is it possible that I have a bad valve and it's unable to pull air from the valve causing all the vacuum to be pulled from the aos?

Edited April 30, 2014 by Punkd

[xmac]

After oil draining, there should only be some residual oil. Look for anything other than oil like metal, plastic, RTV, silicone bits. Once you have that off, it is easy to inspect the oil pickup without removing it. You will also see two internal AOS units inside which behave as oil de-foamers. Might be worth a shot to remove and check that those do not have obstructions (about $35 each to replace). Here is what you will see:

Edited April 30, 2014 by xmac

[dgjks6]

Is the oil pressure always low? In mine the pressure went up almost all the way at start up. When the engine gets warm at idles goes to between 1 and 2. Then goes up with acceleration.

Is yours always low?

What did the shop that rebuilt the engine say about the oil pressure?

[Punkd]

Thank you for the pictures, I'll let you know once I have it all removed.

And no, at cold startup it's between 4-5 once at ~210 it's at half bar.

[xmac]

Thank you for the pictures, I'll let you know once I have it all removed.

And no, at cold startup it's between 4-5 once at ~210 it's at half bar.

That provides some clues. I thought you had low oil pressure even at cold. I'm thinking that it is more likely a temperature issue than oil system. At a cold startup, you should be at full 4-5bar which you are seeing.

If you rev the engine, does the oil pressure move up with RPM's or does it stay at 1/2 bar? Have you removed the front bumper and cleaned the radiators? Was the water pump replaced during the engine work?

_____________

Incidentally, for your P0140 check engine light:

If you can hear the air pump running at cold startup, it is likely your combination valve (#3) in this picture, the vacuum line connecting to it, solenoid that controls it or one of the other vacuum lines is disconnected or mis-connected. Do you hear the air pump running at cold startup? You can also open the rear trunk lid and touch it after a cold startup to see if it is running. Let's work on the oil problem first.

Edited May 1, 2014 by xmac

[Punkd]

Thank you for the pictures, I'll let you know once I have it all removed.

And no, at cold startup it's between 4-5 once at ~210 it's at half bar.

That provides some clues. I thought you had low oil pressure even at cold. I'm thinking that it is more likely a temperature issue than oil system. At a cold startup, you should be at full 4-5bar which you are seeing.

If you rev the engine, does the oil pressure move up with RPM's or does it stay at 1/2 bar? Have you removed the front bumper and cleaned the radiators? Was the water pump replaced during the engine work?

_____________

Incidentally, for your P0140 check engine light:

If you can hear the air pump running at cold startup, it is likely your combination valve (#3) in this picture, the vacuum line connecting to it, solenoid that controls it or one of the other vacuum lines is disconnected or mis-connected. Do you hear the air pump running at cold startup? You can also open the rear trunk lid and touch it after a cold startup to see if it is running. Let's work on the oil problem first.

Cold start pressure is normal 4-5 bars usually 5. Temperature is normal. Hottest it gets is right in the middle of the 0 on the180. I removed both radiators and cleaned them out. Flow is very good. Also I did change the oil cooler during the rebuild. Water pump was changed before the rebuild right Wehrmacht I got the car. Old one was plastic, replaced it with metal pump. Temperature isn't the problem from what I see. I have 3 bars at 5000 rpm fifth gear. It's only on idle when I'm at .5 bar..

As for my secondary pump, it works fine. Off the bat I noticed they messed up with the vacuum lines right by the solenoid they put a Y shaped split which shouldn't be there. Do you think the oil problem may be related to vacuum line mess up? I know they broke a line or 2 but I can arrange the lines correctly.

[Ahsai]

Have you tried hooking up a good pressure gauge to measure the oil pressure directly? The oil pressure sensor is mechanical inside and not the most precise piece of sensor in the world. Of course the oil pressure gauge in the dash may not be very precise either.

[xmac]

You have two independent problems. The oil pressure sender is attached to the passenger side (Bank 2) camshaft cover and is electric, no vacuum connected to it.

My previous comments on temp were based on you posting about 210C temp when hot (post #6). Now that you have provided more info, it circles back to the oil pressure sender. You can either replace it or figure out a way to attach a mechanical gauge to verify the actual pressure.

[Punkd]

Have you tried hooking up a good pressure gauge to measure the oil pressure directly? The oil pressure sensor is mechanical inside and not the most precise piece of sensor in the world. Of course the oil pressure gauge in the dash may not be very precise either.

I have not, unfortunately I'm done being lied to by the shops in my area and I don't have a gauge. I will try replacing the sender unit but I'm a bit skeptical about it because of the fact that I had spun bearings which indicates that my pressure was In fact low. But I'll change it out anyway if I can get my hands on one within the week.

You have two independent problems. The oil pressure sender is attached to the passenger side (Bank 2) camshaft cover and is electric, no vacuum connected to it.

My previous comments on temp were based on you posting about 210C temp when hot (post #6). Now that you have provided more info, it circles back to the oil pressure sender. You can either replace it or figure out a way to attach a mechanical gauge to verify the actual pressure.

Yeah temperature is normal. Ill get a sender just for the sake of ruling it out (I'd be very happy if it solved my problem). And last thing on my mind is the oil pump. What do you guys think? Another mechanic took apart my pump for inspection and said it's in fine condition, but then again a lot of these guys are idiots. I can get a used pump from a Porsche yard nearby for a few bills. But from I understand dropping the engine is the only way to get it on.

[Ahsai]

Even with a new pressure sender, we still can't be sure about the accuracy of the gauge in the dash. I think to be 100% sure, a physical gauge connected directly to the engine is the way to go.

[Punkd]

Even with a new pressure sender, we still can't be sure about the accuracy of the gauge in the dash. I think to be 100% sure, a physical gauge connected directly to the engine is the way to go.

How would I connect a gauge manually though?

[Ahsai]

Even with a new pressure sender, we still can't be sure about the accuracy of the gauge in the dash. I think to be 100% sure, a physical gauge connected directly to the engine is the way to go.

How would I connect a gauge manually though?

Most oil pressure testers come with adaptors. You need the 14mm x 1.5mm one (same as the oil pressure sender). Remove the sender and screw in this adaptor

http://t.harborfreight.com/engine-oil-pressure-test-kit-98949.html?utm_referrer=https%3A%2F%2Fwww.google.com%2F

[fpb111]

Just an information point

http://forums.rennlist.com/rennforums/996-turbo-forum/764827-low-oil-pressure.html

[xmac]

Just an information point

http://forums.rennlist.com/rennforums/996-turbo-forum/764827-low-oil-pressure.html

Good points in that thread.

1. disconnect and reconnect the connectors on the oil pressure sending unit in case it is corrosion

2. disconnect, clean the connection points and re-install engine ground strap visible with the passenger rear tire removed (picture below with green arrow)

3. You can make an oil pressure port on your oil filter housing (new one costs $30 and includes a filter)

edit: green arrow

Edited May 2, 2014 by xmac

[peter911]

Check correct installment of Oil extraction pumps aka Oil Scavenge pumps aka Oil return pumps.