what is oil surge?

Hi - I've heard a few stories about Oil surge and I'm investigating some occurances of blue smoke errupting out the back of my car when cornering hard. My local Porsche specialist is struggling to cure the problem and whilst surfing the net I've found this topic a few times but I can't find anything that explains exactly what the symtoms are - can anyone tell me?

I'm no great expert on this, but the basics are that the centrifugal force acting on the body of oil in the sump when cornering forces the oil to the direction of the outside of the bend. In a horizontally opposed engine this will likely cause the cylinders on that side of the engine to suffer an excess of oil being pushed in their direction and the cylinders on the inside of the bend to suffer the exact opposite. It's exactly this situation in racing which is counteracted by the use of a dry sump engine, hence avoiding a large body of oil sitting in the bottom of the engine. The "GT1" engine design as fitted to the 964, 993 and Turbo and GT3 varieties of the 996/7 are all dry sumped but the Boxster/Cayman and Carrera 2/4 engines are only partially so although I'm sure Porsche would design suitable baffles in the sump to prevent any damage under cornering conditions. There's a bit more information on dry sump engines here http://auto.howstuffworks.com/question331.htm . Hopefully that answers your question at least. Regards Dave

Hi I cannot dispute Computmedics reply. The reason for the blue smoke is that as the oil surges against the affected cylinder bank the piston rings namely the oil clearance rings let some oil by which burns in the combustion chamber. Similarly particularly the exhaust valves which are the lowest in the engine, also get a bit of oil floating around them so some oil will be pumped down the valve guides by the Cam Followers - again blue smoke. I come from a school that says using a bit of oil is not an issue as it is ensuring a bit of lubrication around the hotest and most critical top piston rings . I had a 150bhp 1964 Lotus Elan in 1966, which did 150/200 miles to the pint. This engine I had built to be quick, and it was, but it used oil. However in those days you could buy 5 gallons of fuel for a £1.00. And a pint of Castrol was cheap too! Regards Big Bob

Thanks Guys - very educational. Any idea why this might be happenning to my car though when it doesn't seem to happen to everyone else? I seem to have Oil finding it's way out too easily under heavy acceleration round sweeping bends. I don't mind oil usage either but I don't want the engine blowing up! D'ya think I might I have a problem somewhere that makes this more likely?

As you say, It would appear you have some kind of issue or we`d all experience the same thing. I see no smoke from mine under hard acceleration. Is your oil level too high ? Perhaps the valve stem oil seals have worn and need replacement. Steve

Hi Jona - I've eliminated the oil to high bit already as this was the first thing the independant porsche garage said - they blamed the OPC who recently serviced it. However, we checked the oil, it was just under MAX and off i went and it happenned again - same corner, same time erruption of blue smoke. I've had the Oil seprator changed and that didn't work so we're all scratching our heads over the cause! :?

Hi Abcheetham If you are concerned and want to get to the bottom of it, first get some "Compression Tests" done on each cylinder. This will tell you if there is specific problem on one or more cylinders where "piston ring to bore sealing" may need looking at. If they are reasonably in spec, then valve stem seals could be the next area to look at. Best Regards Big Bob

How did you check the oil? On the 996, the electronic oil indicator is accurate and should be used, not the dipstick. If the dipstick says max, you will have too much oil.

Thanks for the help guys. The oil was checked by the garage, (strasse in Leeds) so I think its safe to assume they did it correctly.I'll see what they reckon to doing the checks etc when I call them tomorrow !!

I think Haran (F1_Dragon) had this issue as well, and got it fixed. Maybe PM him?

PM'd Haran and got a detailed answer, yes it was similar but sadly not exactly the same. I'm taking a bloke from the garage out for a demo this weekend cos "if they can't see it they can't do anything" - apparently! So Satuday early morning I'll take him out and give it some whelly and all being well it'll happen again and they'll see it for themselves! Try not to frighten him in the process!