FNG question

I guess i don't understand wet sumping. just got my '70 cmdo this year.

would appreciate a simple explaination for a dumb old (66) marine.

thanks,
ed

Forget about it. It's an issue full of solutions for which there is no problem. I have had Commandos on/off since my original '71 from back in the day. Never had a problem, never worried about it, never even knew about the term until a couple of years ago. Too much participation on Norton sites can screw up your mind!

I'm sure much will follow to the contrary.

Well wet sumping is a matter of climate on all Commando but also rate of speed in Combats. If really cold and thick oil has drained from tank through gear pump into bottom then some had their oil seals pushed out. I've never bothered to drain sump even in 20'F but keep rpm just over idle till most is pumped to tank then ease up into cam oiling rpm 2000-ish range till residule smoking stops and responds to throttle ok then ride off taking it easy till fully warmed up in a few miles. Combat oil drain is at front so crank sling and acceleration pile oil up at rear where most just gets blown back into tank by breather hose but enough remains to come out where ever is can. Helps some to leave crank throws near TDC on shut downs.

Static wet sumping is where the contents of the oil tank slowly drain down into the sump as the bike sits in the garage, this can take weeks or months depending on how much oil is leaking through the oil pump. When you start the engine as long as they is enough oil left in the tank to feed the crank the excess oil in the sump is returned to the tank. So never fill up with oil without first running the engine, and don't run the engine without checking there is enough oil after a long layup to cover the oil filter in the tank or the crank can be run dry of oil.

Dynamic wet sumping is when as you are riding along and the return oil is less than the feed (reason unknown as the return is sized to be double the feed), oil builds up in the sump and the exhausts start blowing blue smoke. All 72's (including Combats) can do this at high revs as the oil return hole is in the wrong place and the pump never sees the oil to be able to return it.

Oh yes sir kommando has good point on enough oil in tank to run a few seconds before oil returns to tank and not topping tank off til wet sump oil returned, or can over fill and create big oil puddle till reaching its natural level. I've tried to disipline myself to check oil on each shut down of the day to know it time to add or wait another ride or so. NEVER EVER ASSUME YOU"VE ENOUGH OIL TO RIDE OFF ON, w/o checking, as these Nortons seem to go though phases of oil amounts used and can surprise you badly treating it like a modern. BY FAR most Commandos just get started up w/o draining bottom unless set up for a season or more, but then can just add oil enough to flow to pump a few seconds, so the anti-sump solutions are mere icing on cake after thoughts and not anything critical.

Before I knew wet sumping existed, I didn't worry about it. Just started it up and rode. Now, however, it smokes if it wet sumps and it doesn't take mine but a few days to get most of the oil from the tank into the engine. So I installed a valve in the feed line below the tank and no more smoking on start up, plus the engine has stopped dripping oil out of the crank flanges. So, I'm happy I installed the valve and the associated cut off switch to the ignition so I can't start it unless the valve is fully open.

Dave
69S

What's your techno baseline? You know the Cdo is a DRY sump oiling system, right? http://en.wikipedia.org/wiki/Dry_sump "wet sumping" is when oil leaks into the crankcase while sitting for extended periods. The Commando oil pump has been identified as the leaky boot, so to speak. Some bikes are worse than others. Check your oil level in the tank right after you shut the bike off. Then whatever lengthy period you DON'T run it, check the oil BEFORE you start it. If it's down, then that amount is in the crankcase. The accepted benchmark is do not start it if the suction strainer in the tank is not submersed in oil. The answer is to drain the crankcase, then fill the oil tank. HOW LONG it takes to wet sump is the variable. I lucked out, my '74 doesn't leak down any measurable amount in 3 weeks.

Re: Too much participation on Norton sites can screw up your

that's true of most bike forums.

the bmw guys worry about final drive and fuel strip failures ... people post their problems and then everybody worries.

concours said:

What's your techno baseline? You know the Cdo is a DRY sump oiling system, right? http://en.wikipedia.org/wiki/Dry_sump "wet sumping" is when oil leaks into the crankcase while sitting for extended periods. The Commando oil pump has been identified as the leaky boot, so to speak. Some bikes are worse than others. Check your oil level in the tank right after you shut the bike off. Then whatever lengthy period you DON'T run it, check the oil BEFORE you start it. If it's down, then that amount is in the crankcase. The accepted benchmark is do not start it if the suction strainer in the tank is not submersed in oil. The answer is to drain the crankcase, then fill the oil tank. HOW LONG it takes to wet sump is the variable. I lucked out, my '74 doesn't leak down any measurable amount in 3 weeks.

Click to expand...

so what breaks as a result of a wet sump? does the oil lamp stay on after start? does the oil in the sump just stay in the sump?

now i'm thinking i don't know the difference between crank case oil and sump oil.

DogT said:

Before I knew wet sumping existed, I didn't worry about it. Just started it up and rode. Now, however, it smokes if it wet sumps and it doesn't take mine but a few days to get most of the oil from the tank into the engine. So I installed a valve in the feed line below the tank and no more smoking on start up, plus the engine has stopped dripping oil out of the crank flanges. So, I'm happy I installed the valve and the associated cut off switch to the ignition so I can't start it unless the valve is fully open.

Dave
69S

Click to expand...

hey dave,

could you (or anybody else) post a picture of that valve installation?

thx,
ed

Nothing breaks. You may just get more oil below the engine on your floor and a bit of smoking on start up. There may be a slight possibility of the crank seal blowing, but it's disputed and under reported. If you don't experience any problems, forget it.

Dave
69S

PM me if you want info. Or call me if you give phone number by pm.

Dave
69S

goo said:

concours said:

What's your techno baseline? You know the Cdo is a DRY sump oiling system, right? http://en.wikipedia.org/wiki/Dry_sump "wet sumping" is when oil leaks into the crankcase while sitting for extended periods. The Commando oil pump has been identified as the leaky boot, so to speak. Some bikes are worse than others. Check your oil level in the tank right after you shut the bike off. Then whatever lengthy period you DON'T run it, check the oil BEFORE you start it. If it's down, then that amount is in the crankcase. The accepted benchmark is do not start it if the suction strainer in the tank is not submersed in oil. The answer is to drain the crankcase, then fill the oil tank. HOW LONG it takes to wet sump is the variable. I lucked out, my '74 doesn't leak down any measurable amount in 3 weeks.

Click to expand...

so what breaks as a result of a wet sump? does the oil lamp stay on after start? does the oil in the sump just stay in the sump?

now i'm thinking i don't know the difference between crank case oil and sump oil.

Click to expand...

Crankcase oil is circulated thoughout the engine, lines, tank. The portion of the crankcase where the oil collects is known as the sump. In conventional (like your car) engines, the oil is stored in the sump (oil pan) which is the bottom of the crankcase. In the dry sump system, oil (and a bit of air to make sure all the oil gets sucked up) is sucked out (by a scavenge pump) and delivered to the oil tank for storage before being drawn back into the supply pump.
Read this, see if it helps: http://www.dansmc.com/4_stroke_oilpump.htm

thanks for the great inputs, gents. (ntxt)

ntxt

Near as I can tell it goes like this. One guy starts his bike and gives it gentle revs until the oil is circulating and he doesn't notice any problem from the oil that had collected in his sump. Another guy has trouble kicking his bike through, cause maybe his oil pump leaks like a wallet and it is cold and the oil is thick, or maybe his breather isn't up to the job and the pistons are pushing a bunch of air on the downstroke that has no place to go, or maybe his bike is just hard to start. Because it was hard to start, he revs the holy shit out of it trying to keep it running and in the belief this will help. That is about the time that the thick, collected oil blows out the oil seal. Like DogT says, it is something nobody can prove but when one bike keeps loosing the seal and another doesn't , you kinda wonder if there is a difference in the operator.

Of course it is implied in the posts above if not stated that one guy checks his oil tank before starting his bike. They guy who bothers to check knows if he has oil in the sump and is probably the same kind of rider that does stuff like check chain tension, tire pressure and makes sure his anti-sump valve is turned on. But what kind of an idiot would check all this stuff before riding their bike!

Russ

LOL! Rich, even the best attentive operator can't over rev a Commando started in hard freeze and below temps, as it will barely respond to any throttle even with chokes on and ticklers making a mess till warmed up a few moments, so about impossible to blow the seals that way I found. I'd supsect bad seal or bad seal bore or install - if my crank seal leaked in any conditions of wet sump start up. Btw I don't think a factory Cdo can wet sump enough oil to cover the breather vents except in a Combat which functions as secondary return with way more return flow that oil pump. I fear rubbing the cam lobes off during too slow initial rev up so never baby mine on wet sumped starts and keep it over 2000 rpm on every start up unless still very warm. I checked cam/lifers at 7000 miles d/t ring gap issue to be really surprised and pleased no detectable wear - just better smoother burnished finish than Jim Comstock supplied em to Trixie Combat. I also resisted shutting down until at full engine oil temps to avoid not replacing the very thin and easy to wipe off layer of zn-ph nano pads of ZADP additives that get wiped off each start up and don't reform until surfaces oil touches in over boiling hot.

what's this thing for?

something to do with dry sumping? dunno,




a secret government tracking device?

Life is risky and all life styles are fatal so go for it as ya like.

http://www.coloradonortonworks.com/catalog/engine.asp

thanks, lab

that hydralic/ clutch break thing looks pretty cool. might make the drum brakes on my bike easier to live with. a bit pricey for me, though.