|Posted on Monday, July 10, 2006 - 10:28 am: ||
"Got oil dripping out of your crankcase breather(s)?
1. Ensure engine oil level is between full and low marks on dipstick (check hot engine with bike straight and level, insert dip stick fully)."
Has anyone ever discussed this statement about the oil level in the remote reservoir having a direct influence on oil puking?
I have trouble visualizing why the oil level in the reservoir has anything to do with oil being pumped into the crankcase breathers.
My reason is that it would appear the dry sump engine would be blind to whatever the level is in the remote reservoir. All the engine "knows" is that the oil pump is supplying pressurized oil to the filter and then throughout the engine. The oil pump is blind to how much oil (as long as there is some) is in the remote reservoir as long as gravity keeps it flowing down the feed hose.
I know that there would be a slight difference in head pressure in the feed hose to the pump when the oil is really full in the reservoir and when it is really low, but the pump would continue to supply the same pressure regardless.
So, why would the above statement apply to our engines?
For the record, my S2 oil tank has never blown the cap off regardless of how full I have filled it...and sometimes I fill it up past the top ring on the dipstick when I go on a long trip. The triangular tank design leaves plenty of expansion room at the top...vastly superior to the oil bladder design that followed on the S3, S2, M2, X1.
|Posted on Monday, July 30, 2007 - 09:12 pm: ||
I, too, would like to know what difference the oil level makes. I never had any puking problems with several evo Sportys, but my 1999 S3T pukes all the time even with XB rocker covers.
|Posted on Wednesday, August 01, 2007 - 10:16 am: ||
"The triangular tank design leaves plenty of expansion room at the top...vastly superior to the oil bladder design that followed on the S3, S2, M2, X1."
I'm going to throw some stuff on the table here... some of it's conjecture and assumption, but it's all based on the evidence from my particular Buell (2000 M2) and logic.
This is my first drysump bike, so here is the conjecture: dry sump oil pumps scavenge oil from a collection point in the engine and sends it to a separate tank to be fed back into the pump, through the filter, etc. So there must be two functions for a drysump pump, one that scavenges the oil and one that pumps the stuff through.
Here is the assumption: I noticed the scavenged oil is aerated pretty good when it spurts back to the oil bag. The scavenging pump must be whipping that oil pretty good when it pumps it from the cam case to the bag. I think the height of the oil bag is exacerbating this phenomena by having just a little more head (pressure) for the scavenging pump to handle without further whipping the oil into a froth. I think this frothed up oil eventually gets into the bag vent line for the very reason you pointed out why the aluminum tank is better than the oil bag: it has plenty of room for areated oil to settle in before it has a chance to be vented.
Why this assumption? It looks to me like the oil tanks on Sportsters are a lot larger (and lower?) than oil bags on Buells. They don't seem to have as much of a problem as we do, but they notice the same phenoma when they overfill their oil tanks. Also... I noticed a drastic difference in the oil consumption and spooge production on my bike when I lowered the oil bag to just the bottom of the dip stick and ran a larger filter to keep the oil capacity about the same. I think it just creates enough room for the aerated oil to settle before it get blown out of the vent tube, back into the system.
Purely hypothetical... and merely an opinion, but the logic is there (somewhere).