In common parlance, we use the phrase "wet-sumping" to describe two different conditions:
Most correctly (whatever that means) "wet-sumping" occurs when the Return side of the oil pump can't pump the oil back up into the tank as fast as the Pressure side of the pump is pumping it through the system. This is typically caused by failure of the oil pump, but can also be caused by a blocked oil line or oil passage. This sort of "wet-sumping" occurs only when the engine is running, and you notice it when oil starts leaking out of various parts of the engine or starts getting burned in the combustion chambers and smoking a lot.
The more common sort of condition we call "wet-sumping" is when oil slowly leaks past the oil-pump gears and flows from the tank into the crank sump while the engine is not running. This happens to some degree on almost ANY dry-sump bike; even a bike in excellent condition will allow a tankful of oil to leak down over a period of many months or a year. As the oil pump wears out, this leaking goes faster until the bike is filling up its sump with only a couple weeks or less of sitting. You know this is happening when the indication on the dipstick is slowly dropping but there is no oil on the floor under the bike. The oil will be found when you pull the engine sump plate. If more than a quart or two is missing from the tank, you should not start the engine until you find it and put it back.
EDITORIAL COMMENT - The solution to either one of these problems is to fix your oil pump so that it is working properly, something that one ought to want to do anyhow (I would think). A common "bodge" to avoid fixing it properly is to install an "anti-wet-sumping" valve in the oil supply line, which is a bad idea for several reasons described in detail in the archives of this and other lists.
Yes, well, that's what happens when one replies to a post straight from the "15 Latest Posts" list without seeing what brand it was under. Falls under the category of "I have such a good answer to this question that I will now ask it."
I have not the foggiest idea what the mechanism is for wet-sumping on a Triumph, what I wrote is for a BSA. Usually, a Triumph has burned so much oil and leaked the rest past the pushrod tube seals that there's none left in the tank to run to the sump ...
Lannis (yes, I had two of the leaky beasts!)
OK, I admit it, I'm addicted to brake fluid.
But I can stop any time I want.
#116064 - 05/15/0712:01 amRe: what is wet sumping?
I seems to have needled the Lannisquatch somewhat on this one with wot I thought was just an innocent and obective comment.
Does appear that some Beeza blokes have a somewhat of a sensitive disposition unlike us Triumph blokes wot is more laid-back an'all. Can't really blame them though considering wot they has to put up with..
I mean - wot yer gonna do Eh :rolleyes: !
BTW, Lannis - Unless very much mistaken, this is the Triumph section. So wot is you doing here with yer BSA woes :p ?
P.S. Might have gotten myself into a bit of trouble here
Baby - Lannis is correct. "Wet sumping" is when (as he so eloquently described) the sump (or bottom end) of the engine fills with a fluid that shouldn't be there.
To be more specific, IMHO there is "oil wet sumping" and "fuel wet sumping".
• “Oil wet sumping” is just as Lannis described. On a Triumph this is usually because the “return-side” pump is blocked or fouled with trash so that it cannot pump. Other brands like BSA and Norton "oil wet sump" due to gravity/ time.
• “Fuel wet sumping” occurs when you leave your fuel taps ON and fuel runs down the throat of the carb, past the valves and rings and settles in the sump.
On any bike with a breather, the answer to either state will be an immediate “splat” of raw liquid, in volume, landing on the ground under the bike at the end of the sump breather hose. The exact effect will depend therefore on where/ how your engine breather hose is connected.
One other, very bad, result of FUEL wet-sumping can often be that lots of the raw fuel gets pumped back to the oil tank, where it is then re-circulated through the engines causing very unnatural grinding of the whirly bits that ordinarily don't grind to a stop with accompanying ker-bloowie sounds and metal shards falling all around the engine bay.
GrandPaul (does not use emoticons) Author of the book "Old Bikes" Too many bikes to list, mostly Triumph & Norton, some BSA & European "The Iron in your blood should be Vintage"
Wet sumping is accurately described above by our resident experts.
However, "wet sumping" is also the universal comment made by novices to any oil-related (or un-related) engine complaint (too much/not enough oil, oil too hot/too cold, oil returning/not returning, oil pressure/no oil pressure, blocked/tight/wrong/missing OPRV, tight sqeaky rockers/leaking from rockers, lack of power, smoke, high/low engine temperature). It means everything and nothing.
Heck! babyz, if you had posted this in the "Brit bikes in General" section may be we wouldn't have had some of the Triumph v/s BSA stuff !!!!! More seriously, I presume that Fuel wet sumping could take place upon parking for a few hours, or overnight. Am I right? More importantly, how would I know if it happening on my bikes (BSA B31, Matchless G3LS, Royal Enfield Bullet 350), what do I do if it has happened, and what do i do to prevent it happening in the future? please enlighten. Naozar R. Garda.
Originally posted by Lannis: A common "bodge" to avoid fixing it properly is to install an "anti-wet-sumping" valve in the oil supply line, which is a bad idea for several reasons described in detail in the archives of this and other lists. Lannis
Good to have you back posting actively, Lannis....missed you for some time. Regarding your post quoted here, I have hunted all over this site but do not know where to refer to the "archives of this and other lists" that you refer to, and which "other lists" you refer to. I have fitted a "tap" as an effective an "anti-wet-sumping" valve in the oil supply line of my BSA B31 1956, and would like to know more about why it is a "bad idea" barring the obvious one of riding when the valve is shut. Naozar R. Garda.