What's normal oil pressure range?

A failing oil pressure sender gives high readings. Sometimes cleaning the sender connection does the trick.

 

+1. Cleaning the connectors fixed mine

 

Yes, it's good preventive maintenance and you can check the sender's clearance of the torsion bar at the same time...
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What is the proper oil pressure range.

 

The 550 WSM states the oil pressure should be between 5 and 6 bar @ 6000 RPM and oil temperature over 212F. It also states that less than 4.5 bar @ idle is normal.

Some 550's run a bit higher than that; my '99 hits 130+ on a cold morning startup but settles down to the range above when hot.

Mike Sheehan wrote this in 2002 "As for the costs and pitfalls of ownership, the early 550s run much too much oil pressure and occasionally blow the oil filter apart, creating a major underhood mess. Should the oil filter start to leak as an inattentive owner cruises down the freeway, cheerfully chatting on his cell phone, a Ferrari dealer will be happy to install a new engine for a mere $75,000 or so. A rebuild will be in excess of $30,000 if you haven’t managed to spin bearings or score the crank. Preventing the problem is as simple as removing a few spacers in the oil system, which involves an hour’s labor, and drops the oil pressure to real–world levels."

The Good and Bad of 456 GTs and 550 Maranellos

 

Hi John,

I get similar readings as you under the conditions you specified. My 550 is maintained by a Factory-authorized service center and so UFI filters are installed and Shell Helix Ultra SAE 5W-40 oil is used.

The oil pressure gauge on the dash can be checked for accuracy with a gauge connected at the oil sender housing. They did that once with my car several years ago to diagnose a failing sender unit.

I read Michael Sheehan's article a few years ago. I wonder if the oil filters actually ruptured or just loosened. I know my shop properly torques the new filters being installed.

Barry

 

Barry I'd always wondered about the wisdom of adjusting the pressure relief/bypass valves on these oil pumps. Their purpose is to allow the system to bypass "some" oil flow if the pressure gets too high - key words being "bypass some oil flow". So to me, adjusting the pump so it bypasses at a lower pressure is dangerous because you could be limiting oil flow to a part of the engine that needs it.

So if the "system" pressure is too high, where is the restriction and can it be relieved? Initially I thought it might be those teensy weensy oil filters, so I've changed those to much larger and freer flowing Cantons - which didn't help the oil pressure at all. Next I tried changing the oil itself from a 5W-40 to a 0W-40 - that had little to no effect also.

So the "restriction" if there is one, has to be either in the engine itself or the oil cooler, and since the oil cooler is on the scavenge side of the system, it's doubtful that it's the restriction.

Any other theories or viewpoints?

 

John,

I once asked the chief technician at my shop about any need of adjusting the pressure relief/bypass valves. He felt confident that there was no need to do so and that all parts of the engine were being properly lubricated. He didn't seem terribly concerned about high oil pressures indicated by the gauge on the dash. He told me to expect low pressures when idling, 75 or so at highway speeds in 6th gear and readings about 2/3rds up the gauge at the track. He told me to let him know if I didn't get those readings and he'd take a look.

During the four years I tracked my 550, I was on the same service schedule as the Challenge cars; brake fluid changes before events and oil changes after events. So lots of fluid changes, 5-6 times a year. Last year, I was getting some abnormally high oil pressure readings. Not like when the sender failed and I was pinning the needle, just high readings. He cleaned the contacts at the connector and everything read as usual. I drive the 550 in all types of weather. Maybe some tape around the connector will help keep things clean.

Barry

 

Yea, I'd be concerned that if we removed a few spacers to lower the pressure, perhaps "all parts" of the engine would not then get proper lubrication. Don't know if that makes sense the way I've said it, but for example, if it takes 140 psi to lube all parts of the engine with cold oil, then which part of the engine isn't going to get fully lubed if we reset the relief/bypass to 100 psi?

In my opinion, ideally you'd want all the oil from the pump going to the engine, and the relief/bypass would only be there to protect the system in case there was a major obstruction/blockage. However if there were an obstruction/blockage, the engine would be cooked anyway due to oil starvation, so which result is worse?

In the real world, the engine's needs are probably quite a bit less than the full output of the oil pump, so when the pump supplies more flow than the engine can handle, the system pressure rises, and the surplus oil gets bled off/bypassed. It would be good to know, however, how low the pressure can be set and still ensure everything gets lubed properly.

 

Right, John. The chief tech at my shop is a wise fellow and always enjoys this type of discussion. I'll bring it up again when I'm over there on Saturday.

Barry
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Hi John, My Tech Eric at the Auto Gallery did something to a small spring (took a little piece off) the first time he worked on the car to bring the op down, I ask why and he gave the reason above.

It's been perfect ever since.

cheers,

bill

 

Bill, it's good you have a guy like Eric helping you look after your car. He seems like an out of the "yellow box" thinker who doesn't mind going outside the Ferrari parts bins or the WSM for better solutions

 

That's for sure John,

Like the thing he had made to stop the actuators from twisting.

I'm also lucky when in Vegas because I have the guys at PENSKE-WYNN who also look after me, I would ask about changing all the fluids and they would look at em and smell em and say, no all good, we will check again next time you're here.

Between all these people and the fact that I drive it, I have a perfect running 550 with 47k miles !

cheers,

Bill

 

I'm sorry, John. I forgot all about this thread.

I did ask the chief tech about this that Saturday I was there. He explained that several years ago there was a problem with the construction of the UFI filters and he had seen several cases where they failed. He mentioned that he carefully and properly torques the filters to insure they don't loosen. He mentioned that overtightening them might weaken the housing which would make them prone to failure.

Sorry for the late response.

Barry

 

My oil pressure is usually around 3 bar at idle (at operating temps), but today idled at 5 bar. And cruising at around 2.5krpm, oil pressure was at around 8 bar, but is usually more around 6 bar. The weather here today is 48 degrees, but I've still never seen it this high. As a matter of fact, today is a warm day by comparison, and the oil pressure hasn't run this high. I've taken pics; one of the oil pressure while crusing, one of the water temps and one of the oil temps.... both of which were normal.

Should I be worried? I checked the oil level... it's dead on. So it's not over-filled. I'm really thinking the sending unit is acting screwy. Perhaps some water on the contacts?? This did happen right after washing it.
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Nick, you might clean up the terminals on the sender and see what happens. It's a known issue with these senders that when there's enough crud on the gauge terminal for a partial path to ground, it'll give wonky readings.

I've been working with a company to come up with a boot for these terminals to protect them better. Does the pic below look interesting? (disregard the fitting on the end of the sender - that's related to another project for remote mounting these senders):
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John

Looks interesting. I assume the cap will also work on a 1995 456 GT. Had similar problems with my sending unit until cleaned.

AK

 

Yes it does, John. That would prevent the majority of sending unit "failures."

Barry

 

+1 !

 

According to the Ricambi cross reference page, this same sender was used on nearly every Ferrari since the 348 / 512TR's and Maserati's since 2002.

Maybe we could interest Daniel in stocking these covers.

 

Do they come in turquoise? that's my favorite color