B.I. motto "Clean The Sludge Trap"

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Hobot

Hobot

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I need some setting straight about the importance or even wisdom of opening crank merely to check its sludge load. Other British brands seem able to clog up if not pried open now and then. I don't think Norton twins are vulnerable to clogging, just pile up a little bit to form stable flattened area that all future sludge dust runs through the rod shells. I also don't find that an engine blow up can introduce debris into sludge trap and crank slings stuff away from it and a blow up stops turning long before debris can even reach oil tank to matter. Has anyone found a Cdo sludge trap so full it could interfere with rod flow? Did anyone ever find sludge in trap that could just be solvent bathed away w/o mechanical help? Wonder what average time/mileage before sludge is refilled back to normal? Wonder if sump magnet monitoring and adding up gives id of sludge refilling time. If any oil filter advice short of bypass type mentioned please study up on that first.

Would tack welding/soldering/epoxy fasteners still allow bolt stretch to release full clamp force when cold? I've recently been into my mower engine to find my similar torquing held fast and came apart fine with some strain.
 
hobot said:
I need some setting straight about the importance or even wisdom of opening crank merely to check its sludge load. Other British brands seem able to clog up if not pried open now and then. I don't think Norton twins are vulnerable to clogging, just pile up a little bit to form stable flattened area that all future sludge dust runs through the rod shells. I also don't find that an engine blow up can introduce debris into sludge trap and crank slings stuff away from it and a blow up stops turning long before debris can even reach oil tank to matter. Has anyone found a Cdo sludge trap so full it could interfere with rod flow? Did anyone ever find sludge in trap that could just be solvent bathed away w/o mechanical help? Wonder what average time/mileage before sludge is refilled back to normal? Wonder if sump magnet monitoring and adding up gives id of sludge refilling time. If any oil filter advice short of bypass type mentioned please study up on that first.

Would tack welding/soldering/epoxy fasteners still allow bolt stretch to release full clamp force when cold? I've recently been into my mower engine to find my similar torquing held fast and came apart fine with some strain.
Click to expand...

I came in for some 'stick' over not stripping the crank to clear out the trap on my 12K old 850 crank. I just ran solvent (acetone) through it followed by 120psi.
It hasn't failed yet.

I figured that there was a greater risk of failure due to rebuilding with potentially inferior hardware, and I also felt that the full-flow filter on the return would do the job traditionally done by the crank sludge-trap.
They were designed in the age of non-detergent monograde oil, where traps were important, but by '74 I'd guess multigrade was the order of the day, so that combined with a spin-on filter would minimise any build-up.

None of the cranks I've subsequently stripped down have had any significant build-up, but got stripped as part of a full-rebuild with A-N components
 
B+Bogus said:
hobot said:
I need some setting straight about the importance or even wisdom of opening crank merely to check its sludge load. Other British brands seem able to clog up if not pried open now and then. I don't think Norton twins are vulnerable to clogging, just pile up a little bit to form stable flattened area that all future sludge dust runs through the rod shells. I also don't find that an engine blow up can introduce debris into sludge trap and crank slings stuff away from it and a blow up stops turning long before debris can even reach oil tank to matter. Has anyone found a Cdo sludge trap so full it could interfere with rod flow? Did anyone ever find sludge in trap that could just be solvent bathed away w/o mechanical help? Wonder what average time/mileage before sludge is refilled back to normal? Wonder if sump magnet monitoring and adding up gives id of sludge refilling time. If any oil filter advice short of bypass type mentioned please study up on that first.

Would tack welding/soldering/epoxy fasteners still allow bolt stretch to release full clamp force when cold? I've recently been into my mower engine to find my similar torquing held fast and came apart fine with some strain.
Click to expand...

I came in for some 'stick' over not stripping the crank to clear out the trap on my 12K old 850 crank. I just ran solvent (acetone) through it followed by 120psi.
It hasn't failed yet.

I figured that there was a greater risk of failure due to rebuilding with potentially inferior hardware, and I also felt that the full-flow filter on the return would do the job traditionally done by the crank sludge-trap.
They were designed in the age of non-detergent monograde oil, where traps were important, but by '74 I'd guess multigrade was the order of the day, so that combined with a spin-on filter would minimise any build-up.

None of the cranks I've subsequently stripped down have had any significant build-up, but got stripped as part of a full-rebuild with A-N components
Click to expand...


+1.. IMO after spliting and cleaning out that notorious "sludge trap" and in the process disturbing those bolts and fixtures that may have been there 40 yrs. i wouldnt bother next time unless racing, grinding or 7K is in the mix......... Plenty of solvent cleaner with adequate flushing is what i'll be doing next time (unless the obvious is obvious)...
 
If youre running a filter and its off a overhaul , there should be negligable debri ( sludge ) circulteing OR building up , the ' sludge trap ' would be near obsolesent . And could be made so . Particulrly with filter on pressure side of oil pump .

HOWEVER , a Original Build 70s Engine is likely to be all choked up , with sufficent GOOK inside that if it broke free it would lead to tears . need a Survey on Sludge Levels - not that it hasnt been mentioned .
 
Rebuilding my MK3 at around 35,000 for a cam change found very little grayish, hard sludge buildup. Made me wish I had not taken the crank down to bother, but who knew? The bike has always been mine and oil changes have never been neglected and of course Nortons have oil filters which help a lot. Other Nortons I've worked on also had just a bit of hardpack, perhaps a bit more than mine though. Triumphs on the other hand were always packed with black greasy bear shit looking sludge.
 
I fretted over the notorious sludge trap when I got my bike. It had about 20k miles on it and there was no indication that the cases had ever been cracked. A couple of local norton guys said, you are playing with fire if you do not do a complete strip down and cleaning.

The bike had an oil filter since day one. I did a very close inspection of the oil that came out after it's 20 year hiatus. I also ran it for about 100 miles and did another close oil inspection. Nothing magnetic. Nothing but a couple miniscule foreign specs. I decided that I was not going to mess with a bike that purrs like a kitten and runs strong, on the off chance that there is something in the trap. 10k miles later and so far so good.

My theory on running solvent through was that if it was packed down in the trap, why loosen it up into suspension?
I have also read some of the users on this forum who have opened them up only to find little to nothing in the trap after 20 or 30k miles.

Now, my sludge trap may be packed to full right now and ready to do me harm. I will take my chances. When the day comes to split the cases, I will clean it then.
 
Matt the oil filter only reduces the size of the sludge particles collecting that could plug smaller oil ways than journals and if the sludge could break free we'd not have to clean it by direct handling. The fastener risk of new inferior items or not retaining the factory clamp force are the 2 main points I'll avoid in future and just not mention it to avoid the slapping around in public opinion.
 
At 13,000 miles on my 69 there was maybe 1/4" of sludge in one corner of the trap. No oil filter ever used. Probably changed oil too much.
 
One other thing came to mind after reading this thread again. The fear of the existing sludge, somehow "breaking loose" running through the engine. Would not the centrifugal force that packed the admittedly small amount of contaminants into the trap also keep it there. Again Triumphs though, do collect a lot, and it's looser, and there can be enough of it to block oil flow. They also have a relatively easy to remove true trap that can serviced without taking the crank apart.
 
With hard long mileage enough sludge can only build up to the levels already mentioned, ie: til it gives least oil resistance path and flat-est sling out packing, so what ever dust makes it from oil tank sedimentation filtering easy passes through the journal spaces w/o friction. i've seen the nil difference to never filtered to always filters and it an't a whitworths difference. I cut open oil filters on first shut down of first start/heat cycle, while still tingling, to see flecks of brass, Al and sealant. Check and clean sump magnet too for baseline idea of what the filter stopped from passages and metal decay rate the worse it should ever be > till about to wear out something again. I am quick pleased with myself on lack of sump fuzz since going straight to cam break in rpm on first cold start hoping it wet sumped enough till oil flow hits. Only time it increased was after carb boots cracked unknown, then the smoking started. Oh yeah sludge ups the BF a few points so should onset isolation sooner and a bit deeper.
 
Luck of the draw perhaps but think you are mad not to if the crankshaft is out of the bike.
I stripped the 1800 mile crank after lunch today,two oil feed (out of four) holes were blocked and there was a reasonable amount inside the trap and journal inner cavities.
I do not think solvent would have worked from the outside.
It will get the journals polished,a new set of shells and dynamically balanced if I can find a venue.
 
I did split the crank and clean it out on both my bikes. 750 had some fibrous build up in there that looked kind of like dryer lint, except black and pretty tough. I'm glad it's not in there anymore!

850 crank didn't have any sludge, but it was full of rust! I would have blown the motor up if I'd run it like that.

But hey, your bike, do (or don't do) what you want with it... :roll:
 
[quote="B+Bogus

They were designed in the age of non-detergent monograde oil, where traps were important, but by '74 I'd guess multigrade was the order of the day, so that combined with a spin-on filter would minimise any build-up.
[/quote]

#1 in my opinion. Never been into a Norton crank, but I've stripped a few BSA A10 cranks. The ones that had grenaded had traps totally plugged and the others were partly plugged with rock hard crud. Made one good engine out of what I had and a strip down 20000 miles later found the trap perfectly clean. No oil filter, but I've always used top quality 40 or 50 wt oil.
 
Matt Spencer said:
If youre running a filter and its off a overhaul , there should be negligable debri ( sludge ) circulteing OR building up , the ' sludge trap ' would be near obsolesent . And could be made so . Particulrly with filter on pressure side of oil pump .

HOWEVER , a Original Build 70s Engine is likely to be all choked up , with sufficent GOOK inside that if it broke free it would lead to tears . need a Survey on Sludge Levels - not that it hasnt been mentioned .
Click to expand...


I recently got a look inside my 63 Atlas oil tank....there was between 1/4 to 3/8 inch of sludge on the tank bottom. engine has 85 K miles. I think Matt is spot on with his post.

I might argue that running an oil filter prevents sludge build-up....I remember getting into auto engines prior to detergent oils...they had sludge even with filters.
 
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