MK 3 still sumping after replacing spring and piston

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jchill

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At a recent workshop the spring / piston assembly located on back of outer timing case was replaced with a new set

The bike had been sumping oil and I was expecting this to fix the issue
After sitting about a week oil had dropped below check level
Upon opening sump plug about 1/2 quart drained from the case

The new assemble was installed to guidelines with piston moving freely in new spring
I should mention that the replaced assembly was clean and didn't show much if any distress
Has anyone else had this occur and:
Am I missing something here
Any feedback is appreciated
Thanks jc
 
jchill said:
Am I missing something here
Click to expand...

Oil can still leak out along the pump shaft.

Also from the timing cover joint if the part of the gasket surrounding the 'oilway drilling' (below) is broken or damaged.

MK 3 still sumping after replacing spring and piston
 
Thanks for quick reply
There was no external oil leaking from gasket before or after repair
Regarding the pump shaft
how would to determine if that is the culprit and if so is there a fix for
 
jchill said:
There was no external oil leaking from gasket before or after repair
Click to expand...

It's more likely to leak internally, so into the timing chest and then to the sump.


jchill said:
Regarding the pump shaft
how would to determine if that is the culprit
Click to expand...

If the oil isn't draining through the pump because of the anti-drain valve, and no leakage at the pump to crankcase or timing cover joints then as it's a Mk3, the pump shaft is the most obvious source of the leakage (pre-Mk3s can also drain through the OPRV).

jchill said:
and if so is there a fix for
Click to expand...

The pump can be modified to take O-rings (AMR mod). wet-sumping-oil-pressure-relief-valve-and-amr-modification-t21932.html#p291821
 
who cares? the oil gets back to the tank after you run it.
 
Assuming the oil pump gasket is the correct way around, then its the pump or the piston jamming open. I have checked. polished, cleaned it out many times but have found it stick open just as many. Are you correctly determining that it is sumping, there will always be an initial quantity of oil in the sump, is it increasing over and beyond what you would expect there.
 
Normal wet-sumping isn't a problem for machines that are started and run regularly. It's only when the engine sits unused for long periods that the crankcase gets too much oil. In that case, it's either a valve in the line (don't ever forget to turn it on!), the AMR oil pump mod, or unscrew the drain plug and let the oil out. if you drain it into a clean container, you can pour it right back into the tank.
 
Danno said:
Normal wet-sumping isn't a problem for machines that are started and run regularly. It's only when the engine sits unused for long periods that the crankcase gets too much oil. In that case, it's either a valve in the line (don't ever forget to turn it on!), the AMR oil pump mod, or unscrew the drain plug and let the oil out. if you drain it into a clean container, you can pour it right back into the tank.
Click to expand...


Why even do that?
 
jimbo said:
Danno said:
Normal wet-sumping isn't a problem for machines that are started and run regularly. It's only when the engine sits unused for long periods that the crankcase gets too much oil. In that case, it's either a valve in the line (don't ever forget to turn it on!), the AMR oil pump mod, or unscrew the drain plug and let the oil out. if you drain it into a clean container, you can pour it right back into the tank.
Click to expand...

Why even do that?
Click to expand...

Because that takes less effort than changing a blown crankcase seal (as mentioned here before :? ) Although not likely in case of a MK3 with a circlip secured seal.
 
nortonspeed said:
jimbo said:
Danno said:
Normal wet-sumping isn't a problem for machines that are started and run regularly. It's only when the engine sits unused for long periods that the crankcase gets too much oil. In that case, it's either a valve in the line (don't ever forget to turn it on!), the AMR oil pump mod, or unscrew the drain plug and let the oil out. if you drain it into a clean container, you can pour it right back into the tank.
Click to expand...

Why even do that?
Click to expand...

Because that takes less effort than changing a blown crankcase seal (as mentioned here before :? ) Although not likely in case of a MK3 with a circlip secured seal.
Click to expand...

uuumm, never had that happen, learn something every day I guess.
 
Good feedback all
I will take bike out and run a few miles on it let it sit a day etc and =see if any changes
I suppose I be opening the case again regardless

I also have a oil consumption issue
It is not likely the rings and there is no smoke coming from pipes
One theory was the stuck sump spring
 
jimbo wrote:
uuumm, never had that happen, learn something every day I guess.
Click to expand...

Well I have..
Click to expand...

so have I and many other Commando owners, hence the countless posts on this subject

IF the crankcase fills up with too much oil it can put pressure on the seal between crankcase and primary when started

and if that seal weakens oil then enters the primary, sometimes alarmingly overfilling it if the seal is badly damaged

that would be a bad thing to happen as it can soak the clutch causing slipping, among other overfilling issues
 
jchill said:
Good feedback all
I will take bike out and run a few miles on it let it sit a day etc and =see if any changes
I suppose I be opening the case again regardless

I also have a oil consumption issue
It is not likely the rings and there is no smoke coming from pipes
One theory was the stuck sump spring
Click to expand...

Wet sumping is not oil consumption, and oil consumption has nothing to do with a stuck sump spring.
Oil consumption has to do with either rings, valve guides, valve guide seals, or leakage. Without tell-tale blue or white
smoke when running, or a big puddle under the bike as clues, oil consumption can only be measured by how high the oil level
is in the oil tank immediately after running the bike and comparing that with the same value from the previous time(s)
the bike was run.
 
jimbo said:
Danno said:
Normal wet-sumping isn't a problem for machines that are started and run regularly. It's only when the engine sits unused for long periods that the crankcase gets too much oil. In that case, it's either a valve in the line (don't ever forget to turn it on!), the AMR oil pump mod, or unscrew the drain plug and let the oil out. if you drain it into a clean container, you can pour it right back into the tank.
Click to expand...


Why even do that?
Click to expand...

It just makes it easier to kick when the motor has sat unused for a long time. Or if you're referring to pouring it back, that's for all the cheap bastards like me who can't bear to toss a half-quart of good oil in the shitcan.
 
Danno said:
jimbo said:
Danno said:
Normal wet-sumping isn't a problem for machines that are started and run regularly. It's only when the engine sits unused for long periods that the crankcase gets too much oil. In that case, it's either a valve in the line (don't ever forget to turn it on!), the AMR oil pump mod, or unscrew the drain plug and let the oil out. if you drain it into a clean container, you can pour it right back into the tank.
Click to expand...


Why even do that?
Click to expand...

It just makes it easier to kick when the motor has sat unused for a long time. Or if you're referring to pouring it back, that's for all the cheap bastards like me who can't bear to toss a half-quart of good oil in the shitcan.
Click to expand...
It seems I could start my E start on the button or any Norton kicking with an empty oil tank and wait for the oil to come back into it without seals blowing . Must have been lucky all these years. :shock:
 
I'm a little more paranoid about forcing blowby at the rings, which could quickly turn to varnish, especially for bean oil users. It only takes a New York minute to pull the plug and replace it.
 
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