360 - oil pressure readings questionable

I have had my 360 for about 4 years and have driven it about 10,000 miles. Lately, the oil pressure readings have been of some concern.

It is a US car - oil pressure gauge has 5 lines. Line to the far left is 0, line straight up is 70 psi, and line to far right is 140 psi ... 2 other lines are between 0 and 70 and 70 and 140 - lets say these are for 35 psi and 105 psi.

Once hot, idle oil pressure was typically about 25 psi and 75 psi at 4,000 +/- rpm. This was the case for a long time.

Lately, when engine is hot, SOMETIMES idle oil pressure is 40 psi and 4,000 rpm oil pressure is around 100 psi. Other times, it behaves as it did in the past (see above).

It seems that the pressure relief valve cannot be the cause because it should have no effect on the (relatively low) idle oil pressures. Is this a good analysis?

If not PRV - what? Sending unit? Gauge?

Opinions wanted.

Thanks

 

Suspect it is the sending unit. Suggest that you check the pressure with a mechanical gauge to rule out a more severe issue.

 

Sending unit in these cars do give erroneous readings. It's easy to replace although expensive at $218. You can get an aftermarket one for much less but requires a thread adapter. Do a search here -- many posts.
Alan

 

+1 for the sending unit . I had similar problem, there was higher pressure shown at idle close to 10 bar (same position of 140 psi) and then dropped to 5-6 bar(a bit over half of the range) around 4000 rpm. After replacing of the sending unit i now have values close to previous of yours..

 

couldalso be contacts for sending units, sometimes corrosion and simple cleaing up does the trick

 

High probability that it's related to the sending unit.
As Adam stated, try cleaning connection first since it's free. If that doesn't help, replace the sending unit. It's very easy and there are many posts showing the procedure (I think I started a good thread on it).
My sensor went bad causing the gauge to show erratic jumpy readings. The needle would jitter up and down quickly even when the RPM's were steady. I found an OEM sensor on eBay (from a popular Ferrari parts dealer) for $155. It only took me 1/2hr to replace.

 

Chris, can you provide a link to your procedure? This sensor seems pretty tucked in there - did you get at it from above or below? If from below, did you need a lift?

 

Mine pegged out one day on the fwy...I ordered a new one and replaced it. Worked like a charm and much more predictable than the previous one. I do like the adapter in theory but it creates another leak path for the pressure so I think it is prudent to just pay up and be done with it. Of course you will need an oil filter removal tool because it's in the way but that is a nice thing to have. Do a search for that.

 

I had all the same questions. Here is one of the threads:
http://www.ferrarichat.com/forum/360-430/407760-possible-remove-oil-pressure-sending-unit-without-removing-filter.html