Anti sump idea !!!!!!!

Greetings,
I was just reading through the recent "Anti sump failure" thread. I got to thinking the problem (wet sumping) is that the oil tank is mounted above the pump/crankcase. I then began to envision alternative lower mounted oil tanks, possible but too complicated. Then I thought WHY NOT JUST ELEVATE THE OIL LINES !!!!. Just use slightly longer feed line that would loop up over the top of the oil tank. OK, it might still siphon, but does anyone see any possibilities here.

GB

Just like you said, it would siphon.

Jean

1. The true cause of wet sumping is a poor design in the 1972 crankcases where the oil pools and does not feed well to the oil pump pick up. Machining of the cases internal are requires to fix this. Proper venting is done at this time also.
2. Another issue all together that can effect many models, and makes for that matter, is that the oil pump can wear causing a gap where oil can feed back into the case from gravity after sittng for a while. How much oil fed back is relative to the pumps wear. Resurfacing if the oil pump sealing surfaces and pump body can fix this or a fresh oil pump.

Either situation will blow oil past the crank seal to the primary and the like.

Bandade cures like a reed valve on the breather tube fed back to the oil tank or a check valve on the supply line from the tank to the pump have gotten people through till the true remedy can be done, but don't rely on them for a solution forever. And the use of a valve on the supply line should be done at your own risk. I am currently at this stage. Next winter the solution will be had.

This dead horse shall not be beaten down!

"The true cause of wet sumping is a poor design in the 1972 crankcases where the oil pools and does not feed well to the oil pump pick up"

Unless I misunderstand what you wrote (entirely possible ), I don't see how wet sumping can be related at all to the oil pick up in the sump. The wet sumping occurs when the bike is not running so there is no "pick up" occurring anyway. Oil is just seeping down the feed hose, past the oil pump gears and into the sump. How would a "better" feed to the pick up make any difference when the bike is just sitting in the garage?

We should refer to either one of following when discussing wet sumping

1. Static Wet Sumping :- caused by oil being gravity fed through the oil pump and out of the crank.

2. Dynamic Wet Sumping :- caused by oil not being returned to the oil tank fast enough when the engine is running.

MexicoMike said:

"The true cause of wet sumping is a poor design in the 1972 crankcases where the oil pools and does not feed well to the oil pump pick up"

Unless I misunderstand what you wrote (entirely possible ), I don't see how wet sumping can be related at all to the oil pick up in the sump. The wet sumping occurs when the bike is not running so there is no "pick up" occurring anyway.

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To the majority of people these days, the term "wet sumping" is understood to mean a condition whereby oil drains to the sump when the engine is not running (due to slack pump clearances, etc.).

However the original meaning of wet sumping/wetsumping referred to a build-up of oil in the sump whilst the engine was running, usually caused by the scavenge system failing to return the oil back to the tank quickly enough, for whatever reason.

So, wet sumping can have two meanings.

Here is a quote from the OldBritts web site tech articles.

"This Technical article deals with solving the oil pressure loss on the Norton Commandos with crankcases without a sump drain plug. The pressure loss is due to the engine wet sumping at constant high revs. The wet sumping is caused by a poor oil scavenge design on the 1972 750cc engines and was corrected on the 1973 850cc engines. The fix is to modify the crankcases to scavenge oil correctly. This fix involves splitting the cases, which is the hard part, for the actual fix is quite simple. "

They show the entire solution in detail.

Bandade cures like a reed valve on the breather tube fed back to the oil tank

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The reed valve you refer to is to eliminate, as much as possible, crankcase pressure. It has nothing to do with static wet sumping, as far as I can see. If you are referring to it being a band-aid for an engine with excessive blowby, then I agree.

"So, wet sumping can have two meanings."

Got it! Thanks - I was not aware there was an issue with oil pick up on Commandos. But I have been doing most of my research re the 850 and it appears that the 850 does not have the scavenging problem. I had a 750 back in the day and never realized it had any of the problems that are now "commonly known," I just rode the heck out of it!

http://farm3.static.flickr.com/2614/442 ... 2d20d4.jpg

Would this 12 volt valve work for the short term ( for static sumping )? wired to ignition switch, Power on...valve open, Power off...valve closed. This one is 1/2 inch. But, I too, would find it hard to trust anything that could ( if it malfunctions ) block my oil line.

pvisseriii said:

Here is a quote from the OldBritts web site tech articles.

"This Technical article deals with solving the oil pressure loss on the Norton Commandos with crankcases without a sump drain plug. The pressure loss is due to the engine wet sumping at constant high revs. The wet sumping is caused by a poor oil scavenge design on the 1972 750cc engines and was corrected on the 1973 850cc engines. The fix is to modify the crankcases to scavenge oil correctly. This fix involves splitting the cases, which is the hard part, for the actual fix is quite simple. "

They show the entire solution in detail.

Click to expand...

We're all familiar with that solution. My opinion is that the issue that Fred experienced was due to the fact it was his race bike which is typically kept at revs not found on the street. I would not take that effort for a street bike.

I also don't agree with his crankcase ventilation, preferring the Jim Comstock solution. There are too many examples of crankcase ventilation using one way valves (reed) instead of open air breathers.

"the actual fix is quite simple"... if you have a f'n mill. :roll:

medomuffn said:

http://farm3.static.flickr.com/2614/4429549380_5fd62d20d4.jpg

Would this 12 volt valve work for the short term ( for static sumping )? wired to ignition switch, Power on...valve open, Power off...valve closed. This one is 1/2 inch. But, I too, would find it hard to trust anything that could ( if it malfunctions ) block my oil line.

Click to expand...

Failsafe mode on that is closed, so no. You want it to fail open.

swooshdave said:

"the actual fix is quite simple"... if you have a f'n mill. :roll:

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I believe people performed this removal of material with die grinders and the like. Home Depot and the like have many items that can be applied to an electric drill. I grant you, special care and patience are in order to do this whether you have a mill or a Dremal tool with a barrel sander, but completely possible. Stay inside the scribed lines. Walk away alot. The actual process could be done in an hour. The real job is the R&R

I modified mine with a simple drill stand to remove most of the material then hand tools to finish off. Took time, but agree fully with the point about walk away and have lots of cups of tea. There was an adage somewhere about think/measure twice, cut once.

Phil.