On 2 Sep 98 Geraint Owen wrote...

I am having a problem with the dry sump scavenge on a 6 litre engine when the oil gets hot (85 degrees plus). I have three main theories. Any suggestions as to the likehood would be much appreciated.

1. The pump is won-out (thought unlikely)
2. The oil filter (full flow type) for some reason is not of sufficient capaacity
3. I have some rubber tube on the scavenge side of the return pumps. This could be internally collapsing (no external evidence). A bit like sucking too hard on a thick shake!

My feeling is that it is #2, but I dont know if pumping the air/oil mixture through a filter designed to take just oil is a problem. And if so why should it be temp dependant?

John Seim replied...

In looking at your conditions, I assume that 85 degrees is Celcius. I would recommend an oil cooler. The rubber hose could be colapsing. Consult a hydraulic hose house for application 100R1AT or 100R5AT or other rating for oil with temperature ranges that you are operating in. The advise of cavitation and possible gear change may also need some looking into.