Board index Flathead Power-Technical Questions, Answers, and Suggestions Big Twin Flatties wet sumping

wet sumping

Moderators: Curt!, Pa

Post Tue Nov 23, 2010 4:22 pm

Posts: 216
Location: Georgia
All
I still have wet sumping after the bike sits for a few weeks. It probably sat 3 weeks before starting it this time and it puked over a quart. This was the longest it has not been cranked since the oil pump install.

You probably recollect, this is the one I got an oil pump from VT-Cycles in Findland for. As far as the pump operation there is no problem. I know the check valve in the pump is the major factor for this. In looking at the design of the engine I think it can also leak oil throught the cam bushing into the gearcase. Is this a possibility or am I off my rocker?

F

Post Tue Nov 23, 2010 4:44 pm
jib

Posts: 575
Location: devon,england
hi have you contacted vt-cycle about it?
Dude, check out that jibhead, he's crazy. Hasn't been sober for 40 years

Post Tue Nov 23, 2010 5:20 pm

Posts: 216
Location: Georgia
jib
No, not yet. I just figured it was something different than the check valve. It was doing the same thing before I installed this pump. If everyone thinks that is the only possibility I will contact them. I should probably pull the check ball out and inspect it.
F

Post Tue Nov 23, 2010 5:43 pm
jib

Posts: 575
Location: devon,england
hi f, reckon if it was doing it before its not the pumps fault. and yes i cannot see a reason why the oil cant leak past the cam shaft , however would think would have to be quite worn, have you got standard oil tank set up?
Dude, check out that jibhead, he's crazy. Hasn't been sober for 40 years

Post Wed Nov 24, 2010 6:25 am

Posts: 216
Location: Georgia
jib
No, the oil tank is a custom job with a spin on filter built into the left side. I don't see how the vent line could be the problem but could the return line be siphoning the oil back into the engine?

The gear case bushings were given a green light by my machinist. I thought they were what caused the engine rattling noise when I first cranked it. I determined later it was the generator gear lash. Engine is relatively quiet after adjusting the gear lash so that leads me to believe the gearcase bushings are OK. I may be wrong.

F

Post Wed Nov 24, 2010 6:29 am
jib

Posts: 575
Location: devon,england
where does the return line finish is it above the oil level? wondered if the oil was simply draining back through the scavenge pump and filling the cam cover etc
Dude, check out that jibhead, he's crazy. Hasn't been sober for 40 years

Post Wed Nov 24, 2010 6:56 am
panic

..
Last edited by panic on Sun Nov 28, 2010 12:00 pm, edited 1 time in total.

Post Wed Nov 24, 2010 7:55 am

Posts: 3123
Location: Central Illinois, USA
F!

First, just to be clear about terminology:
"Wet" sumping usually refers to the motor flooding while running.
Flooding while sitting is called "static" sumping, and it is a common result of leakage past the ball check.

1940 to 52? SV feed pumps had two ball checks (not counting the by-pass valve).
The best treatment for a leaky ball check is to burnish the seat:
BRNISHR.jpg
BRNISHR.jpg (79.9 KiB) Viewed 8803 times

It is quite possible your modern pump was poorly machined in the first place. Please beware that cutting, lapping, and beating with a drift can cause further damage.

Good luck!

....Cotten

Post Wed Nov 24, 2010 10:35 am

Posts: 216
Location: Georgia
Jib
Return line fitting is in the same location as the original but it has a line inside the tank going across to the filter. It may be siphoning oil. I have the same setup on my 46 FL with no problem. I could let it sit for several weeks with the return line loose. That would answer the question.

panic
This pump is very similar to V-twin pump in the check ball / pressure regulator design. The oil supply gets to the pump gears before the check ball. Check ball prevents oil from flowing into any oil pressure passage. Service manual shows this to be the original design. The major design change is the pump gears are the same as a late Sportster. It looks to me like oil could go past the cam bushing into the gear case. I may be wrong.

Cotton
It is “static” sumping, not wet sumping. My bad. And yes there could be something holding the ball off the seat or a bad seat.

Post Wed Nov 24, 2010 12:29 pm
panic

..
Last edited by panic on Sun Nov 28, 2010 12:00 pm, edited 1 time in total.

Post Wed Nov 24, 2010 2:55 pm

Posts: 216
Location: Georgia
Panic
Thanks for the reply.
Since colder weather is coming up I will have more opportunity to experiment. I have seen older Iron Head Sportsters with a ball valve in the oil tank supply fitting. I thought about doing that before replacing the pump. I have rubber lines instead of metal and pinched the supply line off when I left it before. Only problem is 1 time I forgot to un-pinch the line when I cranked it. I was about to go riding when I remembered. That would have been bad! Pinching the line seemed to take care of the problem before so it's probably not the siphoning issue. I will keep the forum updated with the experiments I do.
F

Post Wed Nov 24, 2010 6:09 pm
panic

..
Last edited by panic on Sun Nov 28, 2010 12:01 pm, edited 1 time in total.

Post Thu Nov 25, 2010 9:31 am

Posts: 216
Location: Georgia
panic
The solenoid it interesting. I could hide it somewhere behind the transmission. Have you used such before and do you know where to get such an animal?

All

HAPPY THANKSGIVING!
F

Post Thu Nov 25, 2010 10:37 am
jib

Posts: 575
Location: devon,england
solenoids great ,until wire comes off,breaks or solenoid fails. there is a inline anti sumping valve that is sold for brit bikes esp bsa's will try and find out some details for you
Dude, check out that jibhead, he's crazy. Hasn't been sober for 40 years

Post Thu Nov 25, 2010 11:22 am
panic

..
Last edited by panic on Sun Nov 28, 2010 12:01 pm, edited 1 time in total.

Post Thu Nov 25, 2010 11:35 am
panic

..
Last edited by panic on Sun Nov 28, 2010 12:02 pm, edited 1 time in total.

Post Thu Nov 25, 2010 12:26 pm
jib

Posts: 575
Location: devon,england
that normally open solenoid looks the trick :D
Dude, check out that jibhead, he's crazy. Hasn't been sober for 40 years

Post Thu Nov 25, 2010 4:48 pm
panic

..
Last edited by panic on Sun Nov 28, 2010 12:03 pm, edited 2 times in total.

Post Fri Nov 26, 2010 6:26 am

Posts: 216
Location: Georgia
panic
I may just put a ball valve in line and hang the ignition key on it as a reminder to turn it on before cranking.
F

Post Fri Nov 26, 2010 8:09 am

Posts: 1668
Location: Interlaken, NY USA

On Frankenstein, I've had a wet sumping problem since day one. Finally gave up and put a petcock in the supply line AND added the standard HD pressure switch to the pump. Added a BRIGHT RED LED as the oil lamp. You do notice the bright light immediately if you forget the valve. It's worked out fine. You turn on the switch, the light comes on, you kick once, the light goes off, or Then, you check the valve and continue starting.
DD


Return to Big Twin Flatties

cron