I need to buy a cam

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L.A.B.

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brittwin said:
"Wet sumping" means that the crankshaft's big-ends & flywheel whip up the oil in the crankcase, providing a rather "random" splash pattern and "oil foam". That kind of unwanted excess "lubrication" may (more or less reliably) help to initially lube the cams at start-up,

Doesn't that pretty much go against what you originally said?? *Immediate* cam lobe (over?)lubrication being beneficial as I see it.

brittwin said:
but it's negative effects are far more signiificant. If most of the oil in the tank has drained into the sump, the oil pump's scavenging side can't pump sufficient quantities of the foamy oil back into the tank,

Well I'm not convinced the scavenge system isn't able to clear the sump of this alleged 'foamy oil'.

brittwin said:
and it's pressure-feed side can't supply the engine's bearings & cylinder head appropriately - thus causing damages elsewhere.

I would never start up with an empty oil tank (and have said so in other posts).

brittwin said:
The best way to avoid "dry cam" problems at start-up - particularly when starting the engine after some weeks in the garage - is to remove the rocker covers and to pour a tea-cup of oil into each one of the head openings.

And I'm sure many Commando owners do that.

brittwin said:
That oil can be taken from the engine's sump if it is really "wet sumping". Doing that some hours before kicking her back into life will ensure that enough oil will will have found it's way down the pushrod tunnels to the cam followers and cam lobes at start-up. That's a method you can trust - "wet sumping" isn't.

I have previously suggested (in other posts) removing the majority of the oil from the tank with a suction gun and (keeping it in a container), as I consider it to be an easier method than removing it from the sump to return it to the tank.

The term *wet sumping* really refers to the scavenge system being unable to keep the sump clear of oil while the engine is running! Unfortunately it seems to mean something different these days (the result of oil draining to the sump).
 
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L.A.B. said:
brittwin said:
"Wet sumping" means that the crankshaft's big-ends & flywheel whip up the oil in the crankcase, providing a rather "random" splash pattern and "oil foam". That kind of unwanted excess "lubrication" may (more or less reliably) help to initially lube the cams at start-up,

Doesn't that pretty much go against what you originally said?? *Immediate* cam lobe (over?)lubrication being beneficial as I see it.

Yes - to a certain degree. However, I am pointing out that "wet sumping" does neither properly nor reliably lube the cams, and is thus no "remedy" for any lubrication problem whatsoever. In fact, it is per se a major problem, and not "advantageous" in any respect. You might also find an occasional somersault with your bike very good cam-lube wise, but I wouldn't .... :D

L.A.B. said:
Well I'm not convinced the scavenge system isn't able to clear the sump of this alleged 'foamy oil'.

A gear oil pump's function depends on the availability of oil, not of an air/oil mix. It is definitely a grieveously bad air-pump, and it's performance is dramatically reduced when it is confronted with tiny oily air-bubbles (foam).

L.A.B. said:
The term *wet sumping* really refers to the scavenge system being unable to keep the sump clear of oil while the engine is running! Unfortunately it seems to mean something different these days (the result of oil draining to the sump).
I doubt that there is any such "rigidity" existent as far as the usage ot the term "wet sumping" goes. The problem is per se a self-exacerbating one, since excessive foamy oil in the crankcase can't be pumped back to the oil tank in sufficient quantities (pls see above).
Apart from rare cases of (solely!) faulty oil return (scavenging) sides of the oil pump, the majority of "wet sumping" problems seems to stem from generally worn-out oil pumps - which also let oil flow more or less freely from the tank into the crankcase.
 

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I've never observed this 'foamy' oil phenomenon you describe (OR lack of oil return flow back to the tank as a possible result of it) as a result of the sump being overfilled on start-up.

Do you have any actual proof of this?

Or is this just theory?




brittwin said:
I doubt that there is any such "rigidity" existent as far as the usage ot the term "wet sumping" goes.

No, not now there isn't.....unfortunately!
 
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L.A.B. said:
I've never observed this 'foamy' oil phenomenon you describe (OR lack of oil return flow back to the tank as a possible result of it) as a result of the sump being overfilled on start-up.
When 50W oil is used, the problem isn't as obvious as with thinner oils.

L.A.B. said:
Do you have any actual proof of this? Or is this just theory?
I've seen it - oil froth being irregularly sputtered back into the oil tank, as well as frothy, foam-bubbly oil coming out of the crankcase drain plug hole. Aren't these obeservations strong indicators of "oil foam" build-up?
All this happened after approx. 10 minutes of engine running at low-to-mid revs, with excessive exhaust smoke and occasional misfiring and irregular tick-over.
The person who demonstrated this to me was the previous owner of my 3rd Commando, and I investigated this matter immediately after having the bike brought home (in a truck). The oil pump was worn-out, and the oil used was a very thin-ish juice. The PO later admitted he had used only no-name supermarket car-oil - a 10W-40 of the cheapest kind - due to the bike's excessive oil consumption. He had simply topped-up the oil tank before each of his occasional rides.
If you have a clean spare oil-pump, you can easily see how poor it works when pumping foamy liquids: drive it with an electric drill for some seconds by letting it work on soap-enriched, foamy water (easy to make, and a good lubricant, too). You'll notice the pump won't do the job.

L.A.B. said:
brittwin said:
I doubt that there is any such "rigidity" existent as far as the usage ot the term "wet sumping" goes.
No, not now there isn't.....unfortunately!
Well - to me (and most likely most others) "wet sumping" describes the penomenon of "too much oil in the dry sump" - regardless of the underlying problem(s) causing this fault - there's obviously more than one..... :wink:
 

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brittwin said:
I've seen it - oil froth being irregularly sputtered back into the oil tank, as well as frothy, foam-bubbly oil coming out of the crankcase drain plug hole. Aren't these obeservations strong indicators of "oil foam" build-up?
All this happened after approx. 10 minutes of engine running at low-to-mid revs, with excessive exhaust smoke and occasional misfiring and irregular tick-over.

Well, you appear to have completely changed the subject!

Running the engine with the sump constantly full of oil for 10 minutes! without the scavenge system working correctly hardly seems to be anywhere near the same thing (which was the scavenge initially clearing the sump of excess oil on start-up).

From what you initially said concerning cam lobe lubrication and possible poor sump scavenging on start-up (possibly caused by foamy oil?) causing oil starvation to the pump supply as a result of *wet sumping* (as you understand the term) now seems to be caused due to a problem of a faulty pump and the use of incorrect oil causing a *wet sumping* (as I would describe it) problem.

Obviously these two different examples of *wet sumping* show that it can mean two different things! This latest example having nothing really to do with what we were originally discussing?

---------------------------------------------------------------------
= Wet sumping?

Either

Sump over-filling due to gravity draining of the oil supply to the sump.

Or

Failure of the scavenge system to clear the sump of oil while the engine is running .

Perhaps it would be a good idea if these two totally different conditions were to be called: static wet sumping? And dynamic wet sumping?
 
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L.A.B. said:
Well, you appear to have completely changed the subject!
Well, I'd :D call it "broadening it's aspects a little" ....

L.A.B. said:
Running the engine with the sump constantly full of oil for 10 minutes! without the scavenge system working correctly hardly seems to be anywhere near the same thing (which was the scavenge initially clearing the sump of excess oil on start-up).
IMHO there is no such thing as "the scavenge initially clearing the sump of excess oil" if the oil quantity in the crankcase is really excessive. Particularly when the crankcase oil level is significantly above the crank's bottom dead-centre position the pump can't get it out at once (no "big gulps" there). In consequence, it is whipped to a foamy froth. OTOH, if the crankcase oil level is lower than that, there's no oil in the sump that is "splashed" about and thus none of it will ever hit the cam lobes.

In consequence, you have a "wet sumping" problem if

a) the scavenging side of the oil pump can't clear the sump (which ought to be dry anyway) after approx. ten minutes, and
b) this aforementioned observation makes clear that an "initial clearing at startup" did simply not happen, and
c) after thorough verification of the engine and some conversatons with the PO there are identifyable causes of the problem:
- worn-out oil pump causing oil tank drain into sump;
- PO's unawareness / neglect exacerbating the problem;
- use of cheap low-viscosity mulitgrade oil further exacerbating the problem.

L.A.B. said:
From what you initially said concerning cam lobe lubrication and possible poor sump scavenging on start-up (possibly caused by foamy oil?) causing oil starvation to the pump supply as a result of *wet sumping* (as you understand the term) now seems to be caused due to a problem of a faulty pump and the use of incorrect oil causing a *wet sumping* (as I would describe it) problem.

I am afraid that you have mis-interpreted what I originally said. I have simply pointed out that a dry sump full of oil ("wet sump") isn't a good thing at all, even though it might provide some added cam lobe (splash) lubrication. I have then pointed out that if the oil tank drains down into the sump, there's so much oil in it that it can get easily whipped to froth, rendering the scavening side of the oil pump almost completely useless.

L.A.B. said:
Obviously these two different examples of *wet sumping* show that it can mean two different things! This latest example having nothing really to do with what we were originally discussing?
From a highly "hypothetical" view, there's a difference. In practice, there isn't. Pls. see below.

L.A.B. said:
---------------------------------------------------------------------
= Wet sumping?

Either

Sump over-filling due to gravity draining of the oil supply to the sump.

Or

Failure of the scavenge system to clear the sump of oil while the engine is running.

Perhaps it would be a good idea if these two totally different conditions were to be called: static wet sumping? And dynamic wet sumping?
If ultra-precise terminology is what you're after, please feel free to do so. However, most gear-type oil-pumps (and the Commando pump is no exception) allow oil bypassing when "static", and are also unable of doing their scavenging job appropriately when they are worn out - and even more so if too much oil has drained into the crankcase, getting whipped to a frothy foam there.
Of course there are other causes of scavenging-specific malfunctions:
- metallic debris caught in the pump;
- oil scavenging holes / pathways plugged.
I haven't yet encountered any of the latter problems, but usually found generally worn-out oil-pumps, showing both "static" and "dynamic" wet-sumping as well as very low oil (feed) pressure when warmed-up. The case I described was a grave one since the PO was not familiar with old brit-iron at all and thus exacerbated the problem.
So what I have been saying (and still do) is that "wet-sumping" is a multi-faceted, self-exacerbating problem - and ist doesn't come along with any real advantages, not even hypothetical ones. Hope this helps.
 
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Although still off topic "I need to buy a cam," when I had my 750 Commando over 15 years ago, it had the breather coming off the crankcases at the back and at the bottom of the crankcase, and after wet sumping (by whatever definition) I found that on initial start up, a lot of the oil was expelled from the crankcases up the breather pipe simply by the crankcase pressure, and not up the normal scavenge pathways.

This may have been one of the few good things about the design of this particular Crankcase breather system.
 

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brittwin said:
IMHO there is no such thing as "the scavenge initially clearing the sump of excess oil" if the oil quantity in the crankcase is really excessive. Particularly when the crankcase oil level is significantly above the crank's bottom dead-centre position the pump can't get it out at once (no "big gulps" there). In consequence, it is whipped to a foamy froth. OTOH, if the crankcase oil level is lower than that, there's no oil in the sump that is "splashed" about and thus none of it will ever hit the cam lobes.

I'm sorry but (to me) it is really beyond belief that you could suggest that the camshaft lobes won't receive any splash lubrication from the (rapidly spinning) crankshaft all contained within such a small space (regardless of the oil level!). And that the scavenge side of the pump will just about stop working if the oil level should rise beyond a certain point! It just doesn't seem to happen does it? Have any other Commando owners experienced this (with a healthy pump)?
 

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Reggie said:
I found that on initial start up, a lot of the oil was expelled from the crankcases up the breather pipe simply by the crankcase pressure, and not up the normal scavenge pathways.

This may have been one of the few good things about the design of this particular Crankcase breather system.

Yes I agree, that has been mentioned on this forum before I believe.
 
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L.A.B. said:
I'm sorry but (to me) it is really beyond belief that you could suggest that the camshaft lobes won't receive any splash lubrication from the (rapidly spinning) crankshaft all contained within such a small space (regardless of the oil level!). And that the scavenge side of the pump will just about stop working if the oil level should rise beyond a certain point! It just doesn't seem to happen does it? Have any other Commando owners experienced this (with a healthy pump)?

I haven't suggested that the cam lobes don't receive any splash oil from the crankshaft. This happens all the time when oil pressure is fully built up - the flywheel keeps throwing excess oil around - but the cam lobes are mainly lubricated by oil from the head draining down through the pushrod tunnels. In due course, your assumption of "wet sumping provides great cam lobe lubrication" is (politely speaking) purely hypothetical, and of no practical value at all.
I also haven't said that the scavenging side of the oil pump will "stop working", but that it'll become rather ineffcient.
Furthermore, Commando owners "with a healty oil pump" would neither experience "static" nor ""dynamic" (as you please to call it) wet sumping.

Your last reply indicates that you haven't either read or understood what I've said or you deliberately chose to mis-interpret everything. Therefore I think that taking this discussion any further is futile.
 
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Reggie said:
Although still off topic "I need to buy a cam," when I had my 750 Commando over 15 years ago, it had the breather coming off the crankcases at the back and at the bottom of the crankcase, and after wet sumping (by whatever definition) I found that on initial start up, a lot of the oil was expelled from the crankcases up the breather pipe simply by the crankcase pressure, and not up the normal scavenge pathways.

This may have been one of the few good things about the design of this particular Crankcase breather system.

Yes, wet sumping also results in a dramatic increase of oil being expelled through the breather. On a Mk.III this is less obvious, since the oil tank breather hose goes into the large black polypropylene air box, which can "accomodate" almost a quart of oil or so before one can actually see it seeping / dripping out at it's air intake openings, which are at the bottom side.
 

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brittwin said:
Your last reply indicates that you haven't either read or understood what I've said or you deliberately chose to mis-interpret everything.

You appear to have repeatedly contradicted what you have previously said (in order to make it fit with your theory) and I just don't agree with the majority of what you have said.

My original question:
One symptom of an overfilled sump being smoking on start-up,-so the oil is obviously being thrown against the cylinder bores, so why would this oil not help to initially lubricate the cam lobes as well?
Note the word initially I don't believe I have said anywhere that this was preferable?

And obviously Les Emery of Norvil apparently knows nothing either??

Quote:
"Camshaft lobes depend on oil thrown by the connecting rods for lubrication, besides the oil feed from the exhaust rockers."

And as far as I can see that would occur from oil fling from an over-filled sump as well as from the crank pressure feed oil escaping from the big ends.

brittwin said:
Therefore I think that taking this discussion any further is futile.

Well at least we can agree about something.
 
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