I have a 2000 C2 Cab with 48k miles on it. The other day, I started driving and after about 5 min, the analog oil pressure gauge was reading at about 1. When I start the car cold, it reads at 5, but after driving it a bit, the gauge drops. The digital gauge reads fine and I checked for leaks, but I found nothing. I also checked the oil in the tank manually and the level was fine.

Has anyone gone through this before? Is the gauge bad, or could it be something worse? I dropped the car off at an indie Porsche mechanic last week and he said that he would look at it today. I was just curious (and a bit worried) that this could be the signs of a larger problem.

Thanks!

 

Reading of 1 at idle or while driving? If at idle, it's a bit low. If while driving, it's a lot low. usually this behavior (the latter) indicates internal leakage.

 

The reading is while driving. The gauge moves up as I hit the gas and goes back down when I let go. If this is internal leakage, is this common, or rare and expensive?

 

Probably need a new sending unit. IF in fact you are at <15 psi, you have a problem or are ruuning Mobil 0W40 in the crankcase which is even a BIGGER problem.

 

So what does it read at say highway speed cruising at 60 mph....Is it 1 then or 1 when at idle? Look at the relationship between oil pressure and RPMs....

 

When cruising at 60 mph, it reads fine at about 4-5 bars. The mechanic called me back and said that he hooked it up to a mechanical gauge and said that it was reading fine, He also checked the sending unit and that was working fine. Apparently this is normal, according to him.

 

yeah that soounds normal....a 1 while at freeway speeds would be low...in fact it sounds like thats high at 60, unless you are in 2nd gear...lol...

 

From what I was told by my dealer (my car had the same problem before I purchased it). It is a common problem. New sending unit. Now you have to have the stuck key, and the RMS and you will complete the 996 list of items that are most likely to break

 

Normal oil pessure readings for the 996:

Cold engine at all engine speeds: 5 bar
Warm engine at idle: no less than 1.5 bar
Warm engine above 3000 rpm: 4 bar+

If you are using the crappy Mobil 0W40, you may experience substantially lower pressure, especially at low engine speeds. Running an engine below 15 psi at anytime greatly increases the risk of scoring of crank and journals.

 

Thanks Everyone. The mechanic put on a new sending unit (as 1999Porsche911 and Gcookie mentioned). That seems to have fixed the problem. Now, I'm crossing my fingers that I don't have an RMS or stuck key issue! BTW, if anyone is in the Baltimore/Washington/VA area, I found a great indie shop called Ralph's Auto that works exclusively on Porsches and they are very knowledgeable and reasonably priced! I was charged $475 for the sending unit including labor and $255 for changing my front brakes and rotors (which I had already bought in advance).