360: High cold oil pressure

Cold (say 40F), my oil pressure goes right off the charts as I spin the motor up. I don't mean redline, we're talking 3500rpm. My personal arbitrary comfort limit is 105psi, which is ~2500rpm when the motor is just waking up. Once it's warm, max pressure is 90ish, right about where it's supposed to be, right?

Steve at Arena put a mechanical gauge on it and he confirmed the behavior. He's going to dig into the oil pump and check the pressure relief valve. The working theory is that maybe the valve is binding up a little.

Curious if anyone has seen this before. Any BTDT info I could send Steve's way would be great.

Random details: '01 360. 24k miles. Redline 5w40 changed yearly.

 

To address a few points above:

1. As mentioned in the post, a mechanical gauge has confirmed the readings. Steve saw 150psi.
2. I always keep it under 4k cold, even less since noticing the problem. I get sky high pressures anyway. As noted, 2500rpm and it's already at 105.
3. Its true that oil pressure is higher when cold but all cars have a release valve to limit the max pressure.

I really dont think this is normal unless the relief valve is undersized. Honestly, though, i cant say i ever noticed the gauge until catching that it looked wrong.

 

Thanks Steve. I'm hoping something similar is found.

 

You certainly could but I think without knowing the root cause, it would be crazy to ignore the issue. If it's a pressure relief valve problem, what's to say it can't start sticking constantly open rather than preventing full opening? That would certainly ruin your day.

 

Quick update.

Through some cosmic alignment, a 360 reading LOW oil pressure is in the shop, also confirmed with a mechanical gauge. Both pumps were out so he swapped them. Problems followed the pumps. Other car cursed with high pressure, mine with low.

Unfortunately (in my eyes) no evidence of a sticking valve in my pump. It apparently slides freely. New springs are on order for both cars. I can see that possibly helping the other 360, but not mine. Springs normally get softer, through use, don't they? Even then, an oil pressure spring doesn't see anything like the cycles of a valve or suspension spring.

I should know tomorrow.

 

Parts came in late so no news yet. Won't know until Monday afternoon. I know I'm driving Steve crazy. I just hate not knowing.

All the external symptoms point to a valve that won't move past a certain point. Max pressure is right on when the oil is hot so the valve must move freely within a limited range, right? Unfortunately, no binding has been found.

 

Picked up the car today. It appears to be fixed with new springs.

I was surprised too.

 

I am no longer surprised because my car is NOT FIXED.

Take a look. A cold start at 46F.
https://www.youtube.com/watch?v=sLlpsy_nK3s

 

Eh, it's a Ferrari, right? Two troublefree years is like winning the lottery.

The oil cooler is on the scavenge side so I don't think it could affect it. The oil/water exchanger you're thinking of is for the transaxle.

I assssume he used the OEM port but I did not ask.

Unfortunately, I need clear my lift of another car before I can start looking at it a little more. What started as an alignment has become one of those recursive "crap, now I have to take THIS off to get to THAT" hassles.

 

Nothing yet. The car is on my lift with the sump off. Pump is still in the car. I was slightly disappointed to find that the valve comes right out when the springs are removed. I had hoped to have an "a HA!" moment when it bound up on something. No such luck.

The valve looks very good with only a tiny bit of marking. Marks are smooth with no gouges.

When I run my finger into the pump, there might be the slightest burr on the bottom of the oil relief hole, or it might be my imagination.

Planning to contact Ricambi today about parts.

 

Looked it over again last night. Although I can't really see or feel any wear, I noticed while moving the piston up and down in the bore that it only takes a tiny bit of lateral pressure to cause it to bind up. It appears that it's possible for the middle "shoulder" (for lack of a better term) to catch the oil relief hole. In that case, the hole would only be partially uncovered, bleeding off some pressure but not all, which is the symptom I appear to have when cold - high idle pressure is ~90psi but it ramps up from there.

Here's the cutaway view of the assembly.


It's tough to see but there are actually 3 interference points between the piston and the bore. The top (pointed to by E), just above the middle (right where the top of the spring terminates) and the bottom (right about the middle of the spring in the picture).

As much as I hate throwing parts at a problem w/o a smoking gun - not to mention having a little discomfort taking the oil pump apart - I'm going to order up the housing, piston, and outer cap (A in the pic). The springs were previously replaced.
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