Sportster Oil Pressure and Dynamics

[Hippysmack]

A reservoir (or bathtub) was constructed to feed oil to the cam port inlet in the top of the pump.
A short piece of 1-1/2“ pipe was cut and and finished on the ends with cut pieces of flange paipe pressed into the 1-1/2” pipe.
Then the joints inside were sealed with 5 minute epoxy followed by POR 15 on the bottom and inside to seal the bathtub to the aluminum bed.
A tap was made in the side of the pipe for a 1/8“ NPT x 3/8” hose bibb fitting.



Here is the initial run showing air coming into the cam port inlet.
I have to seal that bathtub though so I can compare to the 97 pump.

http://www.sportsterpedia.com/lib/ex...hippysmack.mp4

[Hippysmack]

OK, got a problem.
I fired up the pump trying to plug the cam port and knocked off a piece of something into the pump.
I believe it was part of the rubber cap.
I could find anything significant in the pump when I took it apart.
The pump locked up so I took it apart to find the return gerotors wouldn't turn.
I removed and cleaned them and didn't see any damage.
Put the pump back together and it spins fine.
But, the pump locking up ate the inside of the rubber cap so now it slips pretty bad.
The oil being on top of the pump spits oil up between the gear and the rubber causing it to slip.

The gear OD is app 1.22" and I don't have a socket that will fit it.
Anybody got an ideas on what I can turn the pump with?
I have one more rubber cap but the oil on top will cause this again.

[Steve9]

Have a lathe?

[Hippysmack]

Sadly, no metal lathe.
I had first thought of a split collar bored to exact gear OD sliced around the gear and bolted.
But I no longer have access to shop equipment.
I'll probably just use the other rubber cap and try and shield the bottom of the gear.

[Steve9]

Have a mill?

I have made whitney punches putting the stock it the mill collet and holding the tool bit in the vise.

But I'm a butcher

[Iron Mike]

Try a zip tie around your rubber cap. Might be a simple fix

[bustert]

well, been busy modifying my oven to accept 36" guitar frame rails for powder coat and now i was volunteered to cut down an oak tree in the middle of the heat, "REALLY"!!!
like i say really admire the work and the thread really is bringing a lot of things to the afore, BUT, you are really reading an issue that rarely exists in the actual world regarding the pump, NO historical data to back it up, been riding since i was 12 and now 71 and never seen cavitation damage with an mc pump at street level.
i do not view because, they are not real world, it is like using that water well pump to water the garden.
never answered the "?" about cavitation in other parts of the engine and yes it can and does happen and more catastrophic than the pump.
you never answered the "?" about which form of gaseous cavitation you are seeing IF it is TRULY cavitation at all.
eventually i will jump back on this subject, got guitar parts to make and powder.

[Tomcatt]

Originally Posted by bustert

...BUT, you are really reading an issue that rarely exists in the actual world regarding the pump, NO historical data to back it up, been riding since i was 12 and now 71 and never seen cavitation damage with an mc pump at street level...

And over thinking something that is most likely simple: just air leaking into the system...

[Hippysmack]

Originally Posted by Steve9

Have a mill?

I have made whitney punches putting the stock it the mill collet and holding the tool bit in the vise.

But I'm a butcher

No mill either.
I thought about making a wedge, using a compass to strike circle, stake points on it, drill them then gut the rod center of the holes.
Lots of tedious junk. But then I'd have to center up tediously to turn the pump.
But I think I like the quick on/off and understanding nature of the rubber cap.

Originally Posted by Iron Mike

Try a zip tie around your rubber cap. Might be a simple fix

I'll try that, can't hurt.


1998 Oil Pump Sump Passage Dead Stick Vacuum Test:

The sump port hose was plugged off with a vacuum gauge off the hose and the cam port was open to atmosphere.
The vacuum on the sump hose was a steady 50 cmHg.
Then oil was introduced into the cam port hole and the vacuum on the sump hose jumped higher and pegged the gauge.
Vacuum was in excess of 74 cmHg with the actual number not known.
The addition of oil traveling to the sump inlet cavity from the cam port increased vacuum on the hose.
I didn't get a picture of it pegged for obvious reasons..... scampering to cut the drill off.

[Hippysmack]

Originally Posted by bustert

never answered the "?" about cavitation in other parts of the engine and yes it can and does happen and more catastrophic than the pump.
you never answered the "?" about which form of gaseous cavitation you are seeing IF it is TRULY cavitation at all.

I've been wrapped up in oil pumps bustert.
I haven't put any thought in cavitation in the motor til yet.
Therefore I don't have an answer. Maybe you can enlighten us.

I did answer the second "?" that, I don't know.
I was hoping you had some sage for that.
I do know whatever, some of us, saw is more treacherous inside the pump than outside in the hose when higher vacuum is present.
Apparently there are some that think it's just air and who cares...
But you are alluding to gaseous conditions we should all care about.
The thing about that is HEAT is a main ingredient in cavitation.
We've seen how the air bubbles form. Heat changes the variables in that as I've already posted.

edit:
I'm giving up the idea of plugging off the cam port.
The return outlet hose was giving a phhutt-phhutt-phhutt sound but there was no grinding or obnoxious noises.
Just a low pitched phhutt-phhutt sound out the hose.
These two return cavities act as separate units but one affects the other.

In thinking now about the Karling Mod where they capped off the return port;
The inlet itself is plugged AND Jorgen said further modding was done on the cavities to optimize something but no details on those mods.
Now I can say that plugging off the inlet in the top WILL NOT solve the issue WITHOUT either welding up the cam port cavity or milling a path from there to the sump cavity.
(which will lower vacuum on the return passage from the sump).
I have already shown in video, elevation (gravity) will not fill the cam port alone.
It takes vacuum from the gerotors to fill the cavities in the small amount of time allotted before next gear cavity rolls around.

The cavity itself, even though capped at the inlet, will still create an air vacuum that doesn't have any way to fill up with oil.
That pressure will still be delivered to the sump cavity unless the cam inlet cavity is removed or shared.