1940 chief sumping

[jn1972]

I am having trouble with my 40 chief sumping ,the motor including the oil pump was rebuilt about 5 years ago ,last year it started sumping if I did not start for about a week ,now if I do not start every 2 day it will sump,most times I will have to drain the sump at least twice before the oil pump will pick up any ideas thanks jerry

[PaulCDF]

I was having similar periodic wet sumping with my Chief after it would sit a week or two between rides. Someone on this forum suggested the Kiwi EZ drain set up now after a ride I will simply
drain the oil tank into a clean dedicated container, then I refill before the next ride. Problem solved.

[joe fxs fxr]

Is there a check valve like a harley? they have been known to leak by if the seat or ball get dirty or corroded.

[tfburke3]

no valve.The oil leaks by the pump plunger ,getting worse as the clearance increases from wear.
Kiwi has a good video to learn about these pumps.
Tom

[ChiefTwoKicks]

HPIM1290.jpg Although this set-up is on an earlier 35-36 oil pump, Jerry Turner told me how he solved the leakage problem. I made up this one, which is slightly different than his description.
Works well, some people put a switch wired to the ignition switch, so as not to forget to open and close the valve. You would be in trouble real quick if you forgot to open the valve.
This works well if the bike sits for extended periods between riding adventures. All the more reason for a safety switch when the bike sees limited use. This would work with a cast iron pump, probably an aluminum '48 and later too. Not for long term or permanent use. The proper rebuild is recommended, but pumps that need total rebuilds are expensive, if done correctly.
Correct, proper techniques are recommended. This example is only for illustration purposes only. Turners advise to me was the following... Use at your own risk.
I have mixed feelings about exposing this short term solution. I will repeat... use at your own risk.

C2K

[joe fxs fxr]

Probably should hang one of these on the valve handle:

31h5g89CHGL._AC_.jpg

[PaulCDF]

From the 'archives'. Eight plus years ago Gary Start wrote on this subject. I bring this forward:

"01-03-2013, 12:14 PM
As stated previously, the plunger in the cast iron oil pump is the culprit for causing wet sumping. The plunger to wall clearance gets too great and the oil goes straight into the bottom end of the engine.
Although what frustrates people is it does not happen every time. This is caused due to the where the plunger stops when you shut off the bike. If at the middle, you have leakage. If at the ends of the stroke, little to no wet sumping.

Whats the solution:
We take your oil pump, hard chrome the plunger, and hard chrome the oil pump.
Next we grind the the plunger and hone the oil pump so both have a perfect clearance better than new. Since the hard chrome is harder than the original pump material and it's running in oil, you have basically fixed the oil pump for the remainder of it's life time.

The above process is not inexpensive, but it's the best solution to solving the wet sumping issue.

Your rebuild process is quite extensive, after the above we will have the body cad plated, then reasemble the pump.
We then place the pump on our test stand and run it for 1hr and then after it's warm check the pressure the pump produces.
While these pressure numbers are arbitrary, our experience has found that when a pump holds these pressures they seem to work perfectly on the bike.

On a cast iron pump with a 5/8" plunger we want:
at 1200rpm -feed side: 60lbs minimum, and 1 cup volume in 54 seconds with a bleed down not more than 20lbs in 60sec
return side - 30lbs pressure minimum. Our new return gears usually produce 60lbs + on the return side

What's the cost:

CI-pump plunger hard chrome - hone, grind $235.00
Labor rebuild CI Oil Pump and test 3.5hrs - $75/hr
New return gears $50
41367 plunger cap $26
cad plate parts $50
42542 Plunger screw $11.50
misc gaskets/screws $6.50
The above gives you as good or better than new cast iron oil pump.

We usually have a couple rebuilt pumps on the shelf if you want an exchange vs waiting for the time to rebuild your pump. Or if you don't mind waiting, we can rebuild your pump. The biggest problem is CAD Plating - it takes 4-5 weeks on average to get the plating back.

If you have any questions on this our any other issues, please give me a call.

Sincerely,
Gary Stark
Starklite Cycle
951-968-3070
www.starklite.com"

PLEASE NOTE above is for information/discussion only. Above were 2013 prices like everything else likely more today. Believe Kiwi Indian also does oil pump restoration, not sure about "hard chroming" pump plunger or bore or cost.

[tomfiii]

Your pump is loosing prime on return side. Other than rebuilding pump ,put some oil down return line to prime pump.