Word of warning for twin cam owners

[mikeyboy]

Had an interesting conversation with Steve scrimminger today,
Seems he has had to rebuild a couple of twin cam engines due to big end and main bearing failure
His suspicion is that the bikes had been left idling on the side stand(one was a bike instructors machine),
Due to the larger free volume in the cylinder head and head cover it allows the engine oil to " sump" in the left hand side,starving the crank of oil.
Hopefully it will be limited to very few bikes
Worth remembering and avoided I think
Mike

 

[Old Wobbly]

Crikey - not something I would do typically with a wet sump engine, but another chink in the armour..

 

[Andy B]

Guess what I did today?!

Warning heeded!

 

[Beemerman59]

The idea that the engine can be starved of oil when running on the sidestand has been brought up on here several times over the years and got poo poo'd by some as not possible with oil pump etc etc. Personally I've always thought gravity might play a part and never start or run my bike on the sidestand.

 

[TLSgazza]

Must be a BMW thing, considering most Japanese bikes don't have a main stand so are always started on the side stand, my tls included,
I did leave mine running once at the queue at customs at Calais eurotunnel and had some funny stuff going on on the dash after a while, doesn't seem to have caused any long term damage.

 

[JohnnyBoxer]

The idea that the engine can be starved of oil when running on the sidestand has been brought up on here several times over the years and got poo poo'd by some as not possible with oil pump etc etc. Personally I've always thought gravity might play a part and never start or run my bike on the sidestand.

Me neither

 

[Blackal]

I'm calling "bluff" on this one.................

Was the oil-pressure light on? If not - then the oil is getting delivered where it should be, including main and bottom end bearings.


Also, once the fluid film is built up - at no load............ it takes a while for that fluid film to dissipate, even with no oil feed.

Al

 

[JohnnyBoxer]

Must be a BMW thing, considering most Japanese bikes don't have a main stand so are always started on the side stand, my tls included,
I did leave mine running once at the queue at customs at Calais eurotunnel and had some funny stuff going on on the dash after a while, doesn't seem to have caused any long term damage.

No Japs produce a Boxer flat TWIN

Do they

 

[MattW]

Must be a BMW thing, considering most Japanese bikes don't have a main stand so are always started on the side stand, my tls included,
I did leave mine running once at the queue at customs at Calais eurotunnel and had some funny stuff going on on the dash after a while, doesn't seem to have caused any long term damage.

As they're the only manufacturer making a boxer twin, I'd say it's certainly a BMW thing...
(Edit: JB beat me to it )
Conventional fours and v-twins etc will naturally drain from their cylinder heads but a boxer twin on its side stand may not drain properly from the low head.

While I've never taken one to bits, I recall seeing a sectional drawing of a TC which showed what appears to be a little scavenging impeller on the low camshaft which looks like it's supposed to fling oil back down the camshaft tunnel. Seems to imply that the designers might have considered sumping in the rocker cover. Perhaps it doesn't work too well?...

Personally speaking, I've always just started and ridden my oilheads and would never let them idle on the side stand (or indeed the centre stand unless I have to - TB balancing etc). That said, after 6 years of owning an 1100 which wouldn't idle on its side stand anyway, I'm kind of programmed to not even try it with my TC

 

[Blackal]

As they're the only manufacturer making a boxer twin, I'd say it's certainly a BMW thing...
(Edit: JB beat me to it )
Conventional fours and v-twins etc will naturally drain from their cylinder heads but a boxer twin on its side stand may not drain properly from the low head.

While I've never taken one to bits, I recall seeing a sectional drawing of a TC which showed what appears to be a little scavenging impeller on the low camshaft which looks like it's supposed to fling oil back down the camshaft tunnel. Seems to imply that the designers might have considered sumping in the rocker cover. Perhaps it doesn't work too well?...

Personally speaking, I've always just started and ridden my oilheads and would never let them idle on the side stand (or indeed the centre stand unless I have to - TB balancing etc). That said, after 6 years of owning an 1100 which wouldn't idle on its side stand anyway, I'm kind of programmed to not even try it with my TC

What you are alluding to - is oil starvation of the oil pump.

The first indication you have of this - is the oil pressure warning light.

If someone is actually running their bike engine with that low-pressure light on............ I'll be rather surprised.

Al

 

[MattW]

What you are alluding to - is oil starvation of the oil pump.

The first indication you have of this - is the oil pressure warning light.

If someone is actually running their bike engine with that low-pressure light on............ I'll be rather surprised.

Al

I'm fairly sure I know what I'm 'alluding to'

People do all sorts of 'surprising' things like running them on the stands for so long that they melt the sight glass window and dump the contents of the sump all over their garage floor.

If a bike is idling on its side stand, the rider isn't going to be sitting on it and hence isn't going to notice a flickering oil pressure light?...

 

[TLSgazza]

I'm fairly sure I know what I'm 'alluding to'

People do all sorts of 'surprising' things like running them on the stands for so long that they melt the sight glass window and dump the contents of the sump all over their garage floor.

If a bike is idling on its side stand, the rider isn't going to be sitting on it and hence isn't going to notice a flickering oil pressure light?...

Which is what happened to mine waiting at Calais as said above, got back to the bike and oil light was flickering, and engine was a tad warm, seems ok still 3 years later.

 

[Blackal]

Which is what happened to mine waiting at Calais as said above, got back to the bike and oil light was flickering, and engine was a tad warm, seems ok still 3 years later.

Then now I must admit, that this does appear to occur (oil pump starvation)- I'd think on a sump with a low level to begin with, though.

But - as I said in first post......... It takes a long time to destroy the fluid film under no-load conditions.

A

 

[Deleted account 211025001]

Don't most mains/big ends rely on scavenging oil from the sump in a wet sump engine?

So, oil pressure can still be good but with a low oil level due to oil pooling in the head not enough oil may be being scavanged from the sump to lubricate the bearings. Coupled with a lumpy 'boxer' tickover I suppose that could lead to some damage?

TBH though, that seems far too simplistic to be true and I'm inclined to think the same way as Blackal.

Andres

 

[DC]

YAWN!!!!

 

[mikeyboy]

I'm calling "bluff" on this one.................

Was the oil-pressure light on? If not - then the oil is getting delivered where it should be, including main and bottom end bearings.


Also, once the fluid film is built up - at no load............ it takes a while for that fluid film to dissipate, even with no oil feed.

Al

call bluff as much as you like,
however personally, when someone who has as much experience as steve with the boxer twins tells me something like this, i tend to listen to what the man is saying!!
apparently when hot the 1200's have quite low oil pressure at idle speed anyway.
so if you choose to carry on as normal it makes no odds to me anyway,broken bikes keep me in employment
i just thought i would post this up for the many on here that are new to bmw
mike

 

[Lord Snooty]

Thanks Mikey for the heads up. I still need to get round to see you about sorting my fuel strip out

 

[Wreford Miles]

No Japs produce a Boxer flat TWIN

Do they

but they do produces boxer engines

 

[Engineer]

Glad I got rid of my twin-cam and bought the superior LC

 

[ianboydsnr]

I'm calling "bluff" on this one.................

Was the oil-pressure light on? If not - then the oil is getting delivered where it should be, including main and bottom end bearings.


Also, once the fluid film is built up - at no load............ it takes a while for that fluid film to dissipate, even with no oil feed.

Al

I think it's likely to be because it's been on its side for a bit to long!