Wet Sumped to Hydraulic LOCK!

is it possible in some models of Commandos to actually hydraulic lock from kicking over until sump drained? If so about how much oil would that take in the cases?
We just had a post today of this occurring to someone. I and many others have never bothered to drain sump but then again it kicked over enough to start. if locked last thing I'd think of was wet sump but would find out anyway on starting to dig in. So absolutely I'd drain every hydro locked case event but is there more than one in a row to worryabout?

I know my Combat has been over filled by two qt's by DPO to spill two qt's out to our feet after like 47 seconds of blipping. I know for sure real Combats can not lock up with the big tube breather return. But I only know Combats thank you.

I experienced hydraulic lock up about a week ago after my 850 had been sitting for about a month. I thought this was the dreaded "wet sumping" that I have been reading about on the forum. I am a new member and have only owned my bike for 8 months or so. I drained the sump (actually I was going to change the oil and filter anyway) and no more hydro-lock. I weigh about 210 lbs and it would not kick over so I didn't force it.

Ok that makes two reports of wet sump lock up. Hydraulic lock implies no gas space left to compress and all oil pressure escapes blocked or at least very restricted. Wise not to force KS through if not normal force. Did ya happen to note how much oil came out? A hand full have reported their crank seal popping out or leaking after wet sump start, might keep an eye on primary oil level or more leaks from primary and engine oil level till ya know your seal ok. AFT in non E start primaries may help detect its leaks from motor oil in primary, but can be confused with the tranny lube darkening ATF too. Many like me hardly give wet sump a thought and I've come to conclusion - short of lock up full its a good thing for cam lobes before oil splash and oil drain and speed can oil surf the surfaces.

There was only about 1/2 a pint (+/-) in the crankcase if memory serves correctly. The majority of the oil was certainly in the tank. After I changed the oil I went for a ride and everything was as per usual with no extra leaks that I noticed. I usually have a few drips under the bike after I've left it for a day or so anyway. I rode it agin today (it was reaching about 60 degrees here in the gold mining hills of Nor Cal) and there was no wet sumping or extra leaks.

1/2 qt-ish does not seem enough oil fill to lock, but I don't know what's going on yet so hoping experts chime in.
After a couple 3 wk my Combat will have no oil in the tank, so I put a bit in to start then tank fills back up to normal range. Oil drips seen after a ride are just drain offs form rolling heated pressurized oil weeps not usually a stationary external leak. If it happens again you know where to ping us at.

I can't see how it would be possible to get a true hydraulic lock situation inside the crankcase, especially on an 850, as the breather in the timing chest would prevent an actual hydraulic lock or even a significant build up of pressure from ocurring. The displaced crankcase oil would simply be forced into the timing chest through the timing side bearing and holes between the two sections.

If the level of oil in the crankcase was sufficiently high enough for the piston skirts to dip into it as they reach the bottom of their strokes, then, rather like trying to push an upturned bucket down into a tank of water, I think that may be enough to bring the crank an almost dead stop, which could account for the apparent "lock up" feeling when kicking over. I think the crankcase would have to be filled with more than the standard oil capacity for it to happen?

I never used to deal with the wet sumping at all. I just started it and drove. As far as I know it never blew the seal and never had any problem with it locking. And it would sit all winter too. Sometimes for weeks or a month or more in the summer.

Dave
69s

Ok LAB I know about nothing on 850's. The picture I have of descending pistons skirts into oil would be to trap some air under them to compress and still allow crank rotation past BDC the compress charge and fire off. So compressed oil should flow some into TS case via its openings to prevent actual lock up BUT, maybe not flowing fast enough to allow full swing through speed so feels like its hung up? To flush oil up the pushrod tunnels would have to fight though the small bevel gap at front of lifters, so could see how that'd feel like a lock up on fast KS stop action. Something strange occurring on these few lock up reports as they imply not just a tough spot to kick through but Locked stiff stopped. The tiny Combat sump plug is risky to round it off as needs to be pretty snug to be secure.

My logic at this point says ignore and allow wet sump, unless can't kick over, then drain some and ride with the wind,after checking oil tank level of course.

Let me say that there was a small amount of "springiness" when standing on the kick starter, but I could not kick it through. And again I am about 210 lbs. I don't know what was going on, as I've never experienced it before, and it cleared up after draining the oil and refilling.

Thanks for the extra detail of non-solid lock up sense. You hold key to mystery. If you care to contribute to Norton lore solving, after a warm up at home to empty sump, start pouring measured amount of oil into head to and test KS til resists and let us know the ~amount it took. I am surprised there's enough tank capacity to fill sump to hang up, which I take you at your word it did. Just don't blow a seal w/o some ice cream on hand to explain it away.

L.E.N. said:

Let me say that there was a small amount of "springiness" when standing on the kick starter, but I could not kick it through. And again I am about 210 lbs. I don't know what was going on, as I've never experienced it before, and it cleared up after draining the oil and refilling.

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Occasionally, when I kick over (not literally) my 850, the kickstart locks up, as if something has jammed in the mechanism, but it's only the cylinder compression, if I continue pressing down on the kickstart lever it eventually begins to move.

I don't know how it would be possible to hydraulic lock the crankcase on a Norton.

1.There is a breather on the crankcase that would allow any extra oil to be pushed out and go back to the tank.

2. The oil tank capacity is not large enough to completely fill the crankcase.

Extra oil in the crankcase will make them a little slow to kick through but it will not stop rotation. If rotation is stopped then there must be fuel or oil on top of the piston. Petcocks often leak slowly and will cause this. Be very careful about forcing the engine through when there is hydraulic lock on top of the piston. Those rods bend very easily. I have a pretty good collection of rods that have been shortened by this method.

Another problem I have seen that feels just like hydraulic lock happens if you are running a belt drive and the belt is a little too loose. The teeth on the belt will climb out of its groove and stop on top of the tooth. Then the belt gets very tight and rotation stops suddenly and mimics hydraulic lock. Then the next kick it will go right on through and you will wonder what happened. Jim

When this occurred I thought I might be able to "pump out" the crankcase by steady pressure on the kickstart (maybe I should have removed the plugs inthe interest of science) but but I became worried that I might hurt something when it wouldn't go through. Perhaps the temperature being about 30 degrees that day may have played into it. I'm not really interested in trying to recreate it, I'm just glad it wasn't a permanent issue. If it happens again I'll remove the plugs first and measure the oil in the case when I remove it. By the way I don't think my petcocks leak as I've had occasion to remove my gas tank a few times recently when I coated my fiberglas Dunstall tank with KBS which incidently seems to have worked pretty well in that regard. Also I put stay up floats in the amals at a later date and the petcocks didn't leak.

I mentioned in another thread that a friend had this happen to his bike. That bike was a Vincent Comet, they have a timed breather and a large oil tank.
I started the 650ss with a partially full sump the other day, too lazy to drain it. It puked oil everywhere and poured out blue smoke for a bit. From the look of the plugs afterward,I figure one oily start like this probably puts more unwanted carbon on the head than a solid month of riding. I kept the revs low, so no blown seal. As far as the blue smoke, I thought at first it might be just some oil from the top that had drained in there, but it seemed to go on to long for that. I'm guessing some of the oil from the sump squeezes up past the rings when in the overfull state. It's definitely time to install an anti-drain valve on that bike

The seal that I blew with full sump on the Commando years ago was clearly blown, not worn. Pressure had turned it from an inny to an outy. I'm convinced there are extra pressures at work in the cases when badly wet sumped and running.
Perhaps the breather cannot instantly alleviate all pressures in all locations when so much oil is sloshing around?

Glen

There is no question that with a crankcase with an over-abundance of oil will build enough pressure to blow a main seal when kicked over with a normal kick. If you were to push it through easy it would just push the oil back to the tank through the breather.

I have made a habit of pushing the engine through one time easy before I drop my weight on the kickstarter- after bending a rod.

My neighbor brought his Harley out of his garage a couple years back. It had been parked there for several years. He put a pair of jumper cables from his pickup to the battery and hit the starter button. It made a loud pop as the front of the crankcases parted and allowed several quarts of engine oil to run down his driveway. OOPS. Jim

Appreciate the reality checks on essentially hydro locked start issues. I'll pull plugs 1st then sump if needed in the event mine don't ease over TDC once or twice hunting compression to step on it. Trixie only needs kicking on cold am starts wet sumpped with dead battery barely clicking the horn with thick 20/50 this season. Smokes to high heaven for a minture or so, likely from left over bore scores while thick oil thown on it, but then clears up on the roll and nil smoke starts even cold after wards. Smoking side changes mysteriously, sometimes both do but usually by far only one side but not always the same side. I always park for the day on centerstand and crank left near TDC.

I can well envision some hydro shock pressure waves overwhleming seal on fast piston decent before oil has time to spread out. Easy does it on 1st KS tasting should avoid need to drain cam splash oil.

Peel though has some serious wet sump concerns on the fly with the piston oil jets, just a bit less than supply side volume, so will try to size them so factory pump can just suck out the excess but would like some sight glass or pressure meter method to creep up on sump levels. Any idea of how to sight glass case volume. Wet sump in running Norton would be more like blender exploding in weightless space station as it trusted to move to a higher orbit.

After reading this thread a lightbulb suddenly appeared over my head: I thought the bike (an 850/3) was just ridiculously hard to kick so maybe it was just this problem all along! Maybe the electric start problem too! Well, once it gets rebuilt I'll see for sure.

comnoz said:

There is no question that with a crankcase with an over-abundance of oil will build enough pressure to blow a main seal when kicked over with a normal kick. If you were to push it through easy it would just push the oil back to the tank through the breather.

I have made a habit of pushing the engine through one time easy before I drop my weight on the kickstarter- after bending a rod.

My neighbor brought his Harley out of his garage a couple years back. It had been parked there for several years. He put a pair of jumper cables from his pickup to the battery and hit the starter button. It made a loud pop as the front of the crankcases parted and allowed several quarts of engine oil to run down his driveway. OOPS. Jim

Click to expand...

I can imagine how sick he felt with that one! A non productive day is bad enough, but a day of destruction is much worse.

Glen

Talking of bad days, not bad Norton days though, I liked this one:

"When I was working on Hondas in '84 I had a 750 four hooked up on mercury gauges to balance the carbs. I ran it up to make sure it was all balanced out and when I let off the gas it sucked all the mercury in all four columns into the engine. I wish I had a video of the horror on my face!
Dan."

Is it true? who cares

agree - It's a good STORY.