Moisture IN: No matter what, a certain amount of moisture will enter the engine from whatever source, and vent location does not affect this.

Moisture OUT: My gut tells me that moisture is best purged from the system out the head breathers, as vapor, when engine is up to operating temp. Partly because without head breathers, the rockerboxes are a dead-end with a valve cover being the first to cool off on shutdown, so more likely to condense there. Would be no problem if the air was purged from there during warmup, but without head breathers it's more stagnant.

So I'm thinking out loud that cam venting may result in more moisture buildup in the engine, which may or may not eventually leave the engine depending on length of ride, operating temp, and volume net out-flow of air (blowby).

But there is an important difference - supply pump going *out* is restricted by oil filter, passages, etc. If the line from the tank has air in it, and downstream has air in it, that may cause inability to gain traction because air is compressible and the pump volume is small compared to the volume of air downstream. It only takes a small amount of oil in the pump and/or downstream to allow it to prime.

(Personally, I was able to fully install the pump & lines without the pinion gear, so I spun it by hand until oil came out at the filter. Then dropped pump down a little to install pinion gear. I would always recommend this method of priming when possible.)

If the scavenge pump is in good condition, and there is enough oil in it to be wet, it should have a ton of suction at the scavenge port in the CC. It is not really restricted going back to the tank (if your tank to&fro lines are in working order).

concern for CC pressure entering the cam port
Do you really just mean air. ?
If the splash holes are open, then CC and cam chest pressures are equal. Saying "CC pressure" implies that pressure is "fighting" the flow from the sump scavenge port. But it's not, it's all equal.

I'm not saying the statement is false, just maybe it's worded funny. I can see where air coming in the cam-chest port would affect pump performance when it gets to the CC-sump port on the pump, but still the gerotors are spreading and there would be suction there, just not quite as good. (Wouldn't this quickly recover once the oil is there again?)


-Fair enough, I will think about this more.

This shows the de-progression of HD information from the diagrams.
I believe this to be the "U" tube effect bustert?
Oil doesn't gather in the sump but is pushed to the back wall and up.

From -85
http://xlforum.net/forums/picture.ph...&pictureid=366

From -04
Notice, it doesn't show how oil is being picked up by the wheels.
But it is being picked up.
http://xlforum.net/forums/picture.ph...&pictureid=364

Hippy, you correctly stated "...we mis-name wet sumping as oil puking out the vents."

I don't think it's about density or pressure, it's only about flow. In head-vented models is a mechanism for oil/air separting (varies by year) and umbrella valve. We know that the oil/air separator can be overcome if flow is too great. If you have excessive blowby (or some place for other air to get IN) this will not necessarily show up as higher CC pressure, because it can be quickly relieved out the breathers (assuming they flow enough). But this does not give the oil-separator time for the oil to drop out - the velocity is too great. (in other words, there is not more oil there, but what is there doesn't have time to separate).

Now if you have restricted breathers (as factory breather bolts 04-up) then the flow out is restricted, and you may see higher CC pressure but less oil puking, out-flow is limited to closer "match" the ability of the oil separator. But you still have the higher CC pressure causing other problems... which is fixed by less restrictive breather bolts... but then you're back to oil puking.

Am I on the right track so far?

In gerotor pump ironheads shown here the oil DOES gather in the sump and from there the oil is sucked to the return gerotor through a small hole depicted in the cross section just above the number 11. That's the only way oil gets back to the pump. Nothing from the cam case. The oil in the cam case has to drain into the flyweel compartment to be returned.
The pump may be aided by some pressure of the desending pistons but I believe the flywheels have little to do with the oil return, unless the windage from the spinning wheels has some affect.

I don't know a lot about EVOs but I doubt the flywheels play a part in oil return. They just splash lube the cylinders and main bearings. Of course with EVOs I'm just speculating.:rolleyes:

'll also go so far as to say a bigger problem occurs when oil accumulates on top of the factory windage tray (top of the 'X' in the pic below) between it and the wheels.
Rotating oil there easily slows down rotation.
Is that where oil churns and aerates the most?"

Well, if it gets that high then you're already a ways into a wetsumping condition. Trivial at that point.

It wouldn't accumulate there unless it pooled up that high in the CC due to lack of scavenging.

I disagree.
I believe the higher density oil gets slung around and in between the tray and the wheels even if the oil level is lower than the tray.
Look at the length and depth of the sump floor.
You'd have half of your oil tank emptied and sitting on the floor before the level would get that high.
Yet we wet sump at high RPM with reports of very noticeable taxing on RPM all of a sudden.
At that point, do you believe half of the oil in the tank is sitting in the sump filling up to the wheels?

Honestly in speaking of oil inside the crankcase leaving, the only thing I see differently from 77 up is splash hole and tray sizes.
The pump's we have already seen as exactly the same minus a few gear sizes and the 98 up cam port.
The FSMs read the same, the function of the wheels and pistons didn't change.
Mechanically speaking, there isn't that much different in the crankcase.
The cam chest oil drainage changed which took some of that oil out of the CC and then they added more in 04. :doh

the reluctor side is just that, not like a fan on a mower wheel.
oil out the vent due to high flywheel compartment could/could not be related
for one, you have gravity and two you have elevation
on the pooling issue, hd known for that, the manometer shows transition to positive pressure which will have a tendency to hold the umbrella open, and with the coalescer being over whelmed, oil out. remember too that oil from the heads are aided by gravity and lower end diff'l pressure. the older way was via p/r tubes but it seems they have their own circuit.
while density could be a factor, then the issue would disappear when oil temp is hot, can prove this wrong already as i run low oil temps as a cooling agent. i never have oil out the breathers. i really have to run hard to even get 180*f, typically run 130*f. in the winter, i run 80>100'ish.
when i make a hard run, i can tell if oil is pooled when i stop because the rear cyl will huff some smoke, no oil out the breather. if i do a cool down before destination for a mile or so, no issues and this making a 50 mile run @ 5k + 120mph.
i am sure i am running more open breather mounts since i made them myself out of aluminum round stock and flaten to allow for wrench, this is so i can run diverters to carb throat where flow is the greatest and cannot become lazy flow and drop out.
i never looked but i might take a look-see into the manifold to see if there is build up, i am thinking not, but never say never.

Attached pictures - let me know what you think - filename is description for each.

I don't think it's density of oil/air mix, so much as density of air (with or without oil in the mix). Not pictured is when you have too high CC pressure, the oil is "blown around" more. Lower CC pressure the oil is blown around less. Either way can be detrimental in certain conditions. Could this be what happens when incorrect CC balance causes wetsumping?

The volume of oil below the windage tray, when level, I bet is less than half a quart. While engine running and more suspended & pushed towards back could be a little more. A whole quart in the sump would be a LOT while running. Just guesstimating. If you really want to know, while I have my jugs off I could dump a quart in there and see what that looks like (probably been done before though).

one more...