UPDATE: My problem turned out to be a loose connection at the oil pressure gauge. I checked/cleaned and applied Stabilant 22 to all the electrical connections, as well as changed all the bulbes, while I had the gauge cluster apart. Thanks again to everyone who responded. Oil pressure issues can be very, very scary!
I have a concern about the oil pressure on my 1996 F355. Just completed a major using 5-40W synthetic oil. At the end of 20 miles of driving the oil pressure went to zero as i was making a turn. Pressing on the gas pedal, it immediately increased to 10. Each time I came to a stop zero pressure and red light. My mechanic suggested thicker oil. When starting cold the pressure is 70. Anyone have this problem?
Was the pressure good before the service? If yes, one possibility could be that the plug at the bottom of the engine sump, and the further plug inside, were removed (by mistake) and the parts not put back properly. The related parts are numbers 17, 18, 72, 71, 70, 69 and 27. Image Unavailable, Please Login It is not uncommon that the plug 17 is removed thinking it was for the oil drain. The plug is actually for access to the oil pump pressure controlling spring and plunger (70 & 69).
Have you checked the oil level? How many miles do you have on the car? If the oil level is fine my guess is the sender.
May not be the sender because both of its circuits, the low pressure switch and the pressure transducer, show low pressure. It is unlikely that both have developed a fault simultaneously.
That was my first thought, but isn't it possible that the pressure sensor (bellows, capsule , diaphragm or whatever) has a mechanical output linked to both the switch and the rheostat? Could the mechanical element fail (including the diaphragm)?
I believe the pressure switch and the rheostat circuits are separate (thus the large size of the sender) but I have never opened one. Separate circuits (devices) inside would make sense, to provide redundancy. Also, Ralph informed that he had ~70 psi shown when cold which can be taken to mean that the sender and the gauge are ok. Of course, it would be a good idea to first test the sender - I do it using my mini compressor, a pressure gauge and some adapters.
The pressure transmitter is common to go bad, i had similar problems but instead having very high pressure, changed the transmitter and now normal.
For the record:: When starting cold:: I get 80 PSI almost instantly, and it stays at that pressure until the oil temperature gauge gets to 170ºF. When the car is warm:: water is at 220ºF oil is at 230ºF and oil pressure is 30PSI at idle and gets to 50 PSI by 2,000 RPMs. When the car is hot off the track:: water is 230º oil is 275ºF, and oil pressure is 20PSI at idle, 35 PSI at 2,000 RPMs, and 65 PSI at 5,000 RPMs. This car has 75,000 total miles and 5,000 track miles (most of which were driving within 2 seconds of the lap record for cars of 400 HP and 3200 pounds on street tires.)
Continuing the discussion of low oil pressure: The car has 27,000 miles and has not ever had the red light and zero reading on the gauge after a major. My mechanic states that this has occurred in other vehicles such as lambs and Maserati s. He suggests changing out the oil to a heavier oil. The oil in the car is Pennzoil 5W-40.Previous major used NAPA 5w-40 oil with not problem. Another mechanic suggests using Liquid Moly oil 5W-40. or racing oil. Since the gauge indicates readings that others have found, I do not think the sensor or gauge are defective.
If the car when in for service with 5w40 and no problem. and it came out with 5w40 with a problem, it's not the oil.
