Does anyone know if fitting an anti-wet sump device into the oil system can cause less oil to pass into the engine? Since fitting one, in the correct pipe and the right way round I noticed a knocking noise in my engine. I am worried that the oil pressure has fallen and oil is not reaching the little end bearing.
I have an automatic one fitted to my B32. It's been on for over 3 years with no issues. There is next no oil pressure in a single with roller and ball bearings throughout but they depend on a good flow. Can you see oil returning to the tank in regular spurts?
What bike is it?
How large is the hole in the valve you fitted? Obviously it should match the oil line but assume nothing!
The usual cause is forgetting to turn the valve on, no chance of that is there?
There is no pressure feed to the little end , only splash
Unfortunately I have read numerous horror stories regarding automatic anti wet sumping valves on other forums.
Apparently, one dealer stopped selling them!
It's a pain in the arse, but I always remove the oil tank cap after firing up to check the oil return. It's a small price to pay for peace of mind and cheaper than an engine rebuild.
I keep a clean lidded jar and drain the sump back into the tank if the bike has been standing more than a few weeks. I understand why people fit valves in the oil feed but I won't do it. I've had reasonable success getting the oil pumps to seal, a new pump on the A10 reduced the flow from about 1/2 jam jar in a couple of days to the same in a month.
The issue for me is the inherent risk in fitting a shut off valve in an oil feed line. Its almost never done in industry if one has to be fitted it would be padlocked open with 2 keys and an isolation permit required to close it. Fitting something like that to my bike that I can just shut off makes me too uncomfortable. I know you can get "automatic" ones that are interlocked to the ignition, but as someone who used to investigate oil refinery accidents, all most interlocks do is add another failure mode.
To go back to the OP's question: the fitting of the valve may reduce wet sumping but at the cost of introducing another doubt and uncertainty about the oil flow that was not there before. Is the new noise related to the new oil shut off valve? Who knows?
I hope you fitted the valve the right way around..?
I'm new to bikes that wet sump, I now have 2. A 42 Harley and a 47 BSA. I never drain the Harley even after long spells in the garage, I drain the BSA if I haven't ridden it for a week. The other day I rode the BSA without draining the sump and it all seemed to go well. What risk am I taking by not draining a wet sump?
Rob
It's not about "not draining a wet sump" but more about draining a sump where the oil has drained down through standing. Not all do. My A7 and Goldie stood from last November to this March and neither filled their sump. It's the luck of the draw with 70 year old engines.
If the sump has filled and you start the engine you'll create a smokescreen and an oily garage floor...
Thank you, maybe I don't have a problem after all!
I've had many BSAs over the years and some wet sumped and some never did. My current A10 which had a serious wet sump issue has been virtually cured by fitting a new oil pump. In my case I believe the oil path was from the tank around the worn pump gears and out along the pump drive into the timing case, it wasn't passing the anti-wet sup ball valve in the crank case. Obviously the pump set up on the singles is different. Even at its worst the problem was cured by running the engine once a week.
I used to drain the sump of my A50 before every use. But then I read someone saying that they used a simple rule - if the oil was still showing on the dip stick, ride the bike and the scavenge pump will do its job. And if the oil level has drained to below the level of the dipstick, drain the sump and top up. This has worked fine for me for the past five years.
Me too, I take a look and make a guess on how much oil has drained. Most times after anything up to 2 weeks running the engine is enough.
Do all of you park with your engine at TDC?
No, mine stops where it stops.
Quote from: cdsdorset on 15 Jun, 2026, 17:28 Do all of you park with your engine at TDC?
I do if I'm laying it up for a few weeks or longer but what's that got to do with wet sumping? It won't prevent it.
Quote from: Derek996 on 16 Jun, 2026, 10:31 Quote from: cdsdorset on 15 Jun, 2026, 17:28 Do all of you park with your engine at TDC?
I do if I'm laying it up for a few weeks or longer but what's that got to do with wet sumping? It won't prevent it.
Why would it not?
Why do you park it at TDC?
There is a school of thought that it used to save valve springs from unequal compression
Quote from: cdsdorset on 16 Jun, 2026, 22:15 Quote from: Derek996 on 16 Jun, 2026, 10:31 Quote from: cdsdorset on 15 Jun, 2026, 17:28 Do all of you park with your engine at TDC?
I do if I'm laying it up for a few weeks or longer but what's that got to do with wet sumping? It won't prevent it.
Why would it not?
Why do you park it at TDC?
Wet sumping is caused by oil seeping past the oil pump gears. It will do that whether the valves are closed or not.
If I am parking the bike up for an extended time I turn the kickstart until it is against compression so both valves are closed. My thinking is simply to keep the combustion chamber and barrel sealed against atmospheric changes, i.e. condensation and dampness. It will also keep our spiders and earwigs. :D
I can see the point of rhyatt's comment as the valve springs won't be left with a load on them for an extended period.
Hi,
With the big end at BDC there will be a greater draining affect through the crank with oil even being drawn through the pump. With the big end at TDC this affect is greatly reduced as the oil has, to some extent, to go up to seep out. I suppose that there is a slight possibility of the reverse affect of oil from the big end/sludge trap draining down so that there is not enough oil for cold starting.
A few turns of the engine before firing it up will overcome this.
Best solution is to ride or at least run the engine regularly up to temperature thus keeping everything oiled and reducing internal condensation.
Dave.
It may make a little difference on the twins but I doubt if parking with the big end at TDC will make much difference to a single. The spigot feeding the crank from the timing cover on the singles is hardly an interference fit.