Forum bmwbike.com

I am about to install the deep alum oil sump. It came with a distance piece or extension to lower the oil pump screen about 1/2 inch. Is it really necessary to install this extension? The oil level is going to remain the same. There will just be more oil below the end of the dipstick.

Allan,

I also installed Mark's special oilpan, and I also lowered the oil screen accordingly. I would say that as a saftey precaution (in case of low oil levels) it's better the have the intake of the pump a low as possible.

In my particular case I did have difficulties with that distance piece; it lowered the screen too deep. Don't ask my why, maybe the screen on my bike is not original. I ended up making that distance piece a bit shorter.

Another thing with the oilpan. Where I drive there are lots of speed bumps. It seems that the extra CM's do make a difference, and if go over a speedbum at anything more than snailpace, my oilpan will touch the ground.

Hi Alan!

I too have an aluminum deep sump that I installed on my 1960 R50. I got it for the increase capacity and extra cooling.

Don’t even think about leaving off that pickup extension! You are absolutely correct that the oil level at the dip stick remains the same. However, the distance between the pickup screen and the bottom of the pan is not the same without the added extension. You will run out of oil much sooner. By adding the extension you drop the oil pickup BACK to the prescribed depth that the original oil pickup was within the stock pan. By not dropping the pickup it will suck air a lot sooner. If this happens, you’ll be needing a total rebuild since your engine just bought the farm.

The extension’s depth also gives you the added advantage of having an extra ½ quart of oil to pump just in case you lose the existing 2 liters.

Good Luck!

Jeff
Jeffery L. Yost
JLYost@JUNO.com
jlyost@concentric.net
Walled Lake, MI (Near the "Motor City")
USA
1960 R50 Black
VBMWO #5614
BMWOA #82236

From the replies, I believe that:
1. Lowering the oil pickup serves only to suck lower in the sump, in case you let the oil level drop below the end of the dipstick.
2. Not lowering the pickup will not make the motor run out of oil.

If you keep the oil level within the marks on the dipstick, there is no need to lower the pickup with an extension. If you wish to let the oil drop below the dipstick, then the extension will suck up the extra 1/2 quart in the bottom of the deep sump

My restorer has also made the remark about hitting curbs with the lower sump, and the possibility that the aluminum might fracture as it cannot bend.

I will definitely check the fit of the extension if I use it, before I get it locked in place and the gasket sealer spread all over the sump gasket!

Greetings, Allan,

A couple of other points, remembered from my sports car racing days:

The oil is a little cooler near the bottom of the pan, because it's closer to the surface that is drawing the heat out,
and the oil that is higher in the pan is naturally warmer because it has just come out of the engine and stays on the top
until it cools.

Under hard acceleration, decelleration, and cornering, the oil will move around quite a bit in the pan. This can actually
leave the pickup exposed to air.

Of course these would hardly be problems with a BMW single. Just food for thought.

Regards,

Dave

Greetings, Allan,

A couple of other points, remembered from my sports car racing days:

The oil is a little cooler near the bottom of the pan, because it's closer to the surface that is drawing the heat out,
and the oil that is higher in the pan is naturally warmer because it has just come out of the engine and stays on the top
until it cools.

Under hard acceleration, decelleration, and cornering, the oil will move around quite a bit in the pan. This can actually
leave the pickup exposed to air.

Of course these would hardly be problems with a BMW single. Just food for thought.

Regards,

Dave

This question can easily be resolved when you condider thermodynamics. Hot oil tends
to remain on the surface, cool oil to the bottom. Which is better, pumping the just returned
hot oil through the motor again or pumping the cooler oil from the bottom of the sump?
I have yet to see an oil tank which draws the oil from the top portion of the tank.

>

Yes, those issues apply to cars with large sump surface areas and a lot of sloshing under hard forces. Hard acceleration is not a factor with an R27, and don't see how the oil in the sump of a solo bike can be subject to any cornering movement at all. I don't see why the oil will move around more in the deep sump than the stock sump, and I don't see how the pickup on an R27 can ever be exposed to air if the oil level is maintained between the marks on the dipstick.

Allen,

If the sump came with the extension then there is an obvious reason to put it on. Two of the points brought up in the discussion are excellent reasons to put it in.

Reduce possibility of sucking air and cooler oil feeding the bearings.

If it was not needed, the manufacture wouldn't have even made it optional.