Wet sumping?

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ScottMDMC

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Hey Guys,
I am just getting my 75 commando roadworthy and last Thursday after a decent evening ride I woke to a good size puddle of oil under the bike. I have not yet done a full investigation but the oil is running down the left side centerstand leg and forming the puddle. It also seems like the bottom of the oil tank is pretty wet. Is this the wet sumping that I hear about or do I need to dig in there and look for a broken hose or something?
Thanks, Scott
 
Hi Scott
no this is not wet sumping, wet sumping is a term used for the engine oil draining from the oil tank (over a period of time, usually a few days or more) through the oil lines and pump into the INSIDE of the crankcases.
I would suggest you have an oil leak!
As you would appear not to be familiar with wet sumping, one of the issues often caused is overfilling with oil! The oil drains into the crankcases over a few days, the owner checks the oil level on the dipstick, finds it is low, tops it up, then when engine is started the oil magically returns from the crankcases and you then have an overfilled oil tank that chucks it out the tank breather and around the filler neck and slops it all over the place.

Always run your engine for 5 minutes (and do not rev it too much) before checking the oil level.

Cheers
JohnT
 
Check the bottom mounting of you oil tank, a crack forms around the insert for the bottom mounting bolt and leaks oil. Fix is to get it welded using a plate to reinforce the area, additionally you can use bigger front and back mounting rubbers, leave out the bottom bolt and use a block of rubber to support the tank.
 
Actually, wetsumping is when the scavenge cannot keep up with the supply. As far as this issue goes, we simply do not know what else to call it. :)
 
Norton oil tanks slowly or quicky drain through oil pump to fill sump when just sitting still. Some drain the sump before start ups but I gave up on that long time ago and just check to see if enough oil in tank to run oil 20-sec till pump refill tank, then check oil level to top off, very very often and regularly. Combat's have oil drain at front so when kicking up heels the oil piles up faster than pumped out so tends to blow oil out seam when run into the elastic engine rpms. Oil can get into primary to leak at stops if crank seal or the case mount bolts leak. Open primary, check chain tension is about too loose when cold and look see for leak sources. PCV's and the reed valves are good to keep oil in while running.
 
kommando said:
Check the bottom mounting of you oil tank, a crack forms around the insert for the bottom mounting bolt and leaks oil. Fix is to get it welded using a plate to reinforce the area, additionally you can use bigger front and back mounting rubbers, leave out the bottom bolt and use a block of rubber to support the tank.
Click to expand...

Start here. Cracked tank.
 
Craaak ! It's a lot of labour in the middle of summer to pull that tank ,weld up craaak hole and refit , stupid brazed arrangement.
 
Boy oh boy would I rather fix the horn or deal with the oil tank, ugh.

I"d just cold weld JBW it after a good acetone washing and peckering roughen outer surface then let a puddle of JBW set up a day+, or heat, then grind back and paint for a tough-ish rubber cushion to wedge in like me, or glue it on then struggle it back in and fiddle the top mounts best as able. Don't put the bottom bolt in is main thing though. While its out, eventually by someone, might consider sticking in a boss to screw in a temp sensor. Not much room so did mine
sticking forward on RH near bottom. I gave up on the rear top mount and wedged hose on tank ridge and sorta of fastened at top rear by bolt thru rubber washer stack, on two Combats now.
 
Hopefully I can get it out tonight and clean it. It is going to be a bitch ain't it? If I get those oil lines off is there an easier was to refit them? I am so not looking forward to this. Also the rear mounting tab is totally missing so I guess it is guaranteed that the bottom mount is broken too.
 
Ya know evetually in a generation or two all the Commando will all be fully fettered but in mean time the task you face is reason I keep telling myself, this is a real man's motorcycle hobby, to help me bite the bullet again and again. You will likely bleed and swear and maybe even cry a little but it won't do any good till you bleed swear and cry a little bit more getting to it then again installing, ugh. Can have another rear tab welded or brazed on but its still a weak fracture link if in any way solid stiffly fastened down. I used a ~1.5"+ dia rubber O-ring about 1/2" thick to surround the bottom boss and support on batter tray w/o transmitting metal flex to tank bottom. Cushion can be too soft or sags to point of non support. CNW sells a kit but not that hard to brew ya own. IIRC rear fender must come off, so then swing arm is right there begging to bother your time and attention.
 
I blast the tank, braze up both upper mounts and braze on a lower doubler.
Then I powdercoat and re inatall with Hardley Davidson oil tank mounts. Works a treat.
Wet sumping?

Wet sumping?

Wet sumping?
 
Looks like the bung on the bottom is leaking but the bigger leak is coming from the tank filter banjo. Those two big aluminum washers need to be replaced. Anyone find something that works from a auto parts store or Home Depot?
 
If it's leaking from the bottom its not going to get better. I would suspect that the rear mount for the tank is also cracked/broken . I had the same problem and tried to brace the tank for a couple years so that it wouldn't vibrate too much but in the end bit the bullet and pulled the tank. Hardest part of this is getting the bolt out since it is very difficult to reach unless you have a childs hands. I was able to turn it a 1/4 flat at a time until I got it out. Take it out and send it to CNW they do a beautiful job.
Plus side to all this is now you can tighten the horn.
 
ScottMDMC said:
Looks like the bung on the bottom is leaking but the bigger leak is coming from the tank filter banjo. Those two big aluminum washers need to be replaced. Anyone find something that works from a auto parts store or Home Depot?
Click to expand...

Maybe a Dowty seal ?
 
Ok, I got the tank repaired and refitted. How much oil do I need to put in the tank before I start it? Or is Ok to start it with the tank empty and check it after it starts to cycle the oil? I do not want to over fill.
 
ScottMDMC said:
Ok, I got the tank repaired and refitted. How much oil do I need to put in the tank before I start it? Or is Ok to start it with the tank empty and check it after it starts to cycle the oil? I do not want to over fill.
Click to expand...
Put down the wrenches, back away slowly. :shock: Starting the engine with an empty oil tank will result in severe engine damage.
 
first of all drain the sump.

then add two and a half quarts to the tank.

run the bike to heat up and circulate oil.

check oil level and top off no higher than the Full line

EDIT. Drain the sump to determine that it is not too full. Then add 5 to 7 oz. through a valve cover before start.
 
Its not that hard or damaging to start on empty oil tank as long as there's enough in the sump to quickly be pumped to tank to get oil pressure in a few seconds, but better to put enough oil in tank first to cover the filter element then run sump dry and check tank for full top off, which in filled to factory mark may spill out till it reaches its natural level. I do not drain my wet sumps as I figure the crank splash helps oil the cam lobes quicker and pretty rare to blow the crank seal.
 
That is what I did. Just put enough to cover filter, started it just long enough to heat the pipes and then rechecked. Seems like the fix worked and tank is not falling out of the frame, all is good. Now if I can get the plate legal in time, she will be going out to Mid Ohio this weekend!
 
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