Oil pressure gauge in 360 Modena

I've seen the same thing in my '99 360. It seems to mitigate as the oil heats up and I've assumed it's just the pressure gauge unable to read the more viscous "cold" oil as well as it should

 

My oil pressure gauge was hanging out at normal levels (70 psi, midpoint), then suddenly the needle just slammed to max and stuck there (140 psi, far right).

What are the odds that my oil pressure actually doubled for no reason (and the car is going to hurt itself), or....the oil sending sensor is about to go out, and is on the blink (and the car is actually safe to drive)?

 

First check to see if the oil pressure sender wire hasn't fallen off.

https://www.ferrarichat.com/forum/posts/147511108/

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I can't remember if shorting the sender wire to earth creates max pressure or if the wire dangling in space creates max pressure.

Note that there should only be one wire on there.

 

Roger that, will check in the morning and report back. Thanks!

 

Oh hey, one more question: Would wetness cause a malfunction here? This started after I washed it, using a facility with a high-powered sprayer. Might have spewed water where it's not welcome up in there....

 

Did you power wash the engine? Or did you just get a little water inside the engine compartment?

As the problem came back on a second drive, I would say it's not a moisture problem. It should have dried out. More likely a loose wire. Clean and tighten the contact anyway.

(EDIT: but not too tight. The studs sometimes break on oil pressure senders).

 

Did not power wash engine. Engine hatch stayed closed. Water just got in through side grills on either side of glass, and rear grating between tail lamps (my model has a perforated grill there instead of solid body panel).

But yeah, was thinking the same thing. It's dry now, days later.

Will attempt to find, clean, and tighten contact in morning. Thanks!
2003 Modena 360 Spider

 

I have no knowledge whatsoever on the 360, but this pressure sensor does really like the old-school mechanical sensor (wiper arm that slides over a wire-wound resistor) as seen in older Ferraris.

It is mechanical so it does not last forever: in the long run, the wire-wound resistor breaks down causing shorts.

There was a discussion on FChat on how to replace these sensor with modern alternative (https://www.ferrarichat.com/forum/threads/oil-pressure-sender-surgery.103015/#post-135745227).

 

Here is the link to the module that calibrates a modern oil pressure sender to suit an old Ferrari gauge : https://sway.office.com/LVWsbkSxiOXNH6LJ . This was designed by members of this forum.

You could also try a British module that can calibrate any resistive sender to any gauge. Cheaper alternative that should "do the trick", but the calibration is more complex. https://spiyda.com/fuel-gauge-wizard-mk3.html

 

So I searched my 360 Modena spider engine as thoroughly as I could, and never managed to spy this part as pictured. Looks like I'll have to rely on dealership

 

I believe it's forward of the oil tank, below the oil filter.

Item 22T

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You may have to feel around for it.

 

Ooooo great. I'll have another look.

 

Sorry for the 12 month thread resurrection, but did you figure out the problem?
I'm interested because my '02 360 oil pressure gauge is also stuck at max pressure (140), it doesn't move at all, even when oil is thoroughly warmed up.
Thanks

 

The wiring on the sender and the sender itself are the main causes. Process of elimination.

Can you find the sender? Just inspect the wiring for anything obvious.

 

Thanks, I'll have a look around.

 

The 360 oil pressure gauge will be max if it is not connected. Find the sender,the two wires are for: 1) the gauge scale and 2) the red light in the gauge. Remove the wire and ground it to the engine. It the gauge goes to zero, it is the sender. If it stays at max, it is likely wiring between the sender and the gauge.
Very common issue.

 

Thanks, that's awesome advice, much appreciated.

 

The wiring is actually even simpler than this. There is only one wire on the 360 pressure sender (see picture in post 4). The other terminal is unused. The instrument panel processes the signal and translates it into pressure and warning indications.

 

I just did a 355 (two wire) and had it mixed up a bit. Thanks for clearing it up.

 

I have a Maserati Spyder which has the F136 engine (similar to F430). Maserati owners have the pegged max pressure problem as well. I have found that if you turn the key on and wait until the oil pressure warning light goes out and then start the engine the oil pressure gauge will work correctly. Try it, but remember the pressure will be high until the oil heats up. Also, on the Maserati the gauge goes to max pressure when you turn the key on and the engine is not running. Now that's goofy because the pressure should be zero. The fault may be the sender but I think the electronics are screwed up as well.

 

The wiring diagrams for the F430 show a 3 wire oil pressure sender. I haven't figured out what the wires are for yet. One is an earth (unlike the old types which use the sender metal case as the earth). The other two wires go to the instrument panel. One wire will be the gauge wire, the other could be for warning light or perhaps it could supply power to the sender.

 

After further investigation (on the F 430):

Green wire: Power for the sender from the Instrument panel. This could explain why the oil pressure indication takes time to show the correct indications.
Black/purple: earth wire
Grey wire: Output signal from sender to Instrument panel

Probably set up something like this:

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Qavion, thanks for your info but you've missed the point I was trying to make. That is, waiting until the oil warning light goes out before starting makes the gauge work correctly and not stay pegged at max. For what it's worth the Maserati has the one wire system for oil pressure and no oil temperature.

 

I think I did understand your point, Tony. I was trying to say was that as the instrument panel provides power to the sender on the F430, the power may not be sent until the instrument panel was happy. What I didn’t know was that the Maserati was a single wire system. This opens up the possibility that the 360 is the same. As the 360 sender is only one wire and that is attached to the instrument panel I guess you could say that the instrument panel is also providing power to the sender.

We just need a 360 owner to confirm this behaviour.