After a week I got about 500ml out but no more even if left it longer. With the cam chest cover off I was getting some oil weeping from the 2 bottom securing bolt holes though.
Would agree with pretty much everything you've written here. I would point out, though, that the M3W is not direct injection, nor does it have an AOS, just an unfiltered calibrated opening into the inlet manifold.
My conjecture is that wet sumping is not endemic to the X-wedge design, but instead related to inadequate manufacturing quality control of the oil pump. Changing oil to a non recommended, non synthetic should only be viewed as a short term fix. Better to address the underlying issue and replace the oil pump, which is admittedly expensive.
As an additional data point, my machine has about 10k miles, runs 20-50 synthetic (H-D spec) and I started it a few days ago for the first time since early November-so a pretty long lay up. It also has an added AOS setup with a clear reservoir which allows me to see what's being pumped out of the camchest on it's way to the intake. The AOS captured only a tiny amount of frothy oil during the 5 minute warm up period. That of course does not mean I have zero wet sumping going on, only that it is low enough that neat oil isn't being sucked out of the camchest area.
If we were to take a comprehensive survey of how many machines have wet sumping issues vs how many do not, I think that would be useful. We should also remember the rule of forums: negative posts on vehicle problems dominate, as the owners without issues are out enjoying their machines vs searching forums for answers.
Steve, how does the reed valve play into the wet sumping? I know it is in the breather path but is it supposed to keep oil out of the sump?
I checked my reed valve and it does not sit perfectly flat on the case and oil could easily. Leak past it. I thought about trying to fix it by lapping the case to truly flatten the seat/case side but don’t feel good about doing it in the car.
I think this was less than a week of sitting without a start.
Last edited by LightSpeed; 28/10/2101:37 AM.
The light at the end of the tunnel is actually a train. 2019 M3W
Apologies if there was a reply expected, as up till a couple of days ago I did not get notifications of any responses to threads I had contributed to... I do get them now though they seem random. As I have typed I have zero M3W experience and no specialist knowledge. I am guessing the oil in sump issue is no big deal initially but over time and build up it could considerably increase carnk-case pressure to the extent is blows a gasket or worse still cause contamination of the CAT as from that which Bitsobrits typed there seems to be no AOS in the system..?
Bunny, not that I doubt your choice of tubing, just that others might think any clear tube might do the trick.... Given the proximity to engine heat, and subject to cracking in time.. I suspect you chose tubing well up to the task as well as resistant to impact from road debris..
I think it must have something to do with build quality in the engine as I have never suffered from this issue and my M3W spends up to 6 months without starting the engine.
Bruce 1964 4/4 Series V Comp (Megan) 1994 +8 (Maurice) 2013 M3W (Olga)
I think it must have something to do with build quality in the engine as I have never suffered from this issue and my M3W spends up to 6 months without starting the engine.
I suspect you are correct. When i took the reed valve apart to check to see if there was anything amiss that I might be able to rectify i noticed a high spot in the case keeping the reed valve from closing completely. I noticed that high spot on it by looking at the polished area on the reed itself. About a 1/4” diameter area of discolor, and then looked for corresponding spot on the case and sure enough there was one. Putting a super flat hone onto the surface of the case keeping everything parallel would be tricky and probably get crud into the oil passages.
If i ever have to break the case open I am going after that defect.
Last edited by LightSpeed; 28/10/2104:42 PM. Reason: spelling
The light at the end of the tunnel is actually a train. 2019 M3W
The reed valve (and the breather system in general) has nothing to do with wet sumping, so best to leave it alone. The reed valve is simply a one way valve that allows excess crankcase pressure to vent into the cam chest area and preclude most of it from returning.
Wet sumping has been covered enough on this forum that I'm not going into repetitive detail here. What I will say is that some of these engines exhibit a significant amount of wet sumping over short time periods while most seem to have no practical problems. This is most likely down to manufacturing issues with the oil pumps.
Using no more than logic, flawed or otherwise, it seems machine tools start of sharp, and after performing some number of cuts may well be re-sharpened or replaced. As I remember production, there were means of checking the quality of manufacturing at various processes to ensure acceptable tolerances were achieved..? I suspect much depends on whether the engineers are in charge or the bean counters to determine just how much "tolerance" might be acceptable..? Thus it seems that one engines oil pump gears may have a tighter mesh than another with the creation in variable outcomes as reported
Seems to me that the thinner the oil the easier task it might have in finding it`s way past the gears..?
I suspect thicker oils may not be an easy answer given the lubrication requirements of modern engines..?
Steve, so its pump tolerances that are causing it. Maybe i should be searching for a tight toleranced pump.
Thank you.
Unless your engine is puking oil out of the cam chest breather/air cleaner or the main seals when starting up, you don't have a problem worth worrying about. Some amount of oil in the crankcase after sitting for a time is inevitable. Drainback from the heads and cam chest alone could be many ounces. Even with a quart or so in the crankcase, the scavenge side of the pump will rapidly clear it (back to the oil tank) likely by the time the engine starts.
Mine wet-sumps a full 2 Litres (2.1 quarts) when left for a couple of weeks without running. I used to worry about it but not any more as it just gets pumped back into the tank when the starter cranks the engine. The car is coming up for 10 years old and isn't leaking oil from anywhere untoward. Fingers crossed it'll be OK long term too...
