Is this normal?

[moribundman]

Does this seem like a fairly complex system, or is this "normal" in other engines, too? These are the components that regulate oil pressure in my V6 Audi engine:

The oil pump is capable of putting out 200 psi.

Oil pressure relief valves:
- 16 bar (232 psi) in oil pickup assembly
- 11 bar (160 psi) safety valve, only opens at high RPM and cold engine temp

- Pressure relief valve in the oil pump
- one pressure valve on each head. Those control top-end oil pressure.

- Two oil check valves in the steadying chamber (under the valley pan), but those don't really do much in terms of pressure control; they just keep oil in the lifters when you shut the engine off.

There's also some pressure control done by the head gasket - each one has a finely-tuned obstruction to oil flow that maintains oil pressure in the engine block when the oil pressure relief valves are open.

 

[Ed]

Sure sounds to me that you have a rather exotic engine lubrication system. Some of those pressures appear awfully high. You probably should follow the oil recommendations from Audi to the letter. The designers must have something in mind when they came up with this.
IMHO it's a perfect example of OVER-ENGINEERING typical of European and specifically German cars.
Whats next? hydraulically calibrated lugnuts?
Ed

 

[moribundman]

That's just a lowly 12 valve engine. That engine has been around for way over a decade and was replaced with a much fancier 30 valve engine in '97.

Whether or not it's over-engineered is the question. Those engines are pretty hard to kill and run forever (unless the timing belt jumps or breaks).

But I agree, the system seems rather elaborate.

PS: 5W-30 to 20W-50/10W-60 is specified.

[ July 11, 2004, 06:33 AM: Message edited by: moribundman ]

 

[moribundman]

Okay, let me rephrase this, since I'm not getting much feedback here:

How's the lubrication system on your car control oil pressure? Or maybe you don't you know?

 

[Gene K]

Is it over engineered? That depends on what kind of problems they were seeing during design that required this elaborate oil system.

Gene

 

[moribundman]

So the lubrication system is complex due to problems in the design?

 

[Gene K]

I cant say what was acceptable to the engineers. But obviously they are there for a reason. If the design team felt they were not needed they would not have used this elaborate system.

They may have been addressing problems that would not even considered a problem by an american engineer but good enough. I do not know what wear rates were deamed acceptable to various components during the design of the engine.

This may be designed to get oil to the top-end as soon as possible without exceeding the capabilites of the seals. This may explain why German OHC engines can run much higher viscosity oils while Americam OHC designs which sometimes starve for oil with High Viscosity Oil on start up. As matter of fact the early Mopar 2.2L OHC killed the cam with only 10W-30 for this very problem.

This may be designed to allow a very high-volume pump to fill large passages fast that can cope with long extended drain intervals without being closed off even if there is some sludging.

Or extremely high oil flow rates to cool and lubricate the valvetrain during extended autobahn operation.

There are I am sure a few Mechanical Engineers on this site who can you a better idea of what potential problem this system was designed to adress.

Gene

 

[moribundman]

You've pretty much summed up what I "think" is behind this elaborate system in this essentially basic and not fancy engine. I believe it's more a system tweaked to optimum performance than a (not even simple or cheap) fix. I'd love to know how some newer Audi engines are designed, as they do have a redesigned oil pump and lubrication system in order to utilize A2 rated oil.