VP AD41B Idle Reduced Oil Pressure

[orion1210]

Hi all, hoping I can tap into the collective wisdom and experience on here.

My port AD41B suffers reduced oil pressure at idle when hot, stable around 15-20 psig, but can trip the LP switch if I come off the plane and to idle too quickly. Picks back up with a little bit of throttle. I suspect from observing indicated oil pressures at various rpms that something is going on the with the piston cooling valve. This engine also takes longer for the coolant to warm up, possibly because the oil is taking some additional heat away at a guess.

I’ve finally got around to pulling the oil cooler/filter assembly off hoping to find something obvious. The only two observations:
1) there was a bit of ‘grit’, approx 3mm, stuck fast on the piston cooling valve seat exactly where the valve would contact.(assumed from when previous owners had the cooler repaired, opened filter paper is spotless thankfully)
2) both valve seats have an approx 1-2mm chamfer where the valve would contact.

In your experience do you think that the 3mm opening on the cooling valve could cause this low idle oil pressure?

Should I worry about the slight chamfers on the valve seats reducing the spring pressure and therefore reducing oil pressure slightly?

Thanks

 

[oldgit]

Seem to recall spending much time worrying over the the apparent low oil pressure on idle on high hours 40A and then high hours 41B engines.
After few thousand hours in both boats internet research suggested that it was just par the course for these engines.
At high engine revs the oil pressures were "good" and when coming back to idle after a run the temperatures soon dropped and the oil pressures stabilised.
However in both instances both engines gave the same oil pressures at low idle.
In both instances one of the engines always ran at a small higher temperature than the other , never did discover why.
Doubt it was much to do with the calorifier.

 

[BruceK]

For your turbo sake its good to come off the plane at a measured pace. You'll find the pressure will also decrease then at a measured pace. On the oul cooler the valves are super cheap and easy to replace so no harm in replacing them if in doubt

 

[Montemar]

If the grit held the valve open slightly then some pressure must have been lost