peterm,
Words of wisdom indeed… not. A higher head of liquid will give more pressure, think water towers. A lower head gives less pressure. In an engine there is no head of oil, it’s the pump that does the work. The pump is above the oil.The oil pressure will remain the same until the level gets dangerously low, meaning there’s no oil left for the pump to pump. Low oil pressure usually means worn bearings or a faulty pump. Back to school for you.
I guess Physics is a foreign language to you, because you have no idea what your talking about,
A Water Tower uses Gravity to Empty,
And talking of Heads, If you had a Dozen Brains you’d still be lonely,
Well I can see I’m getting to you when you start the personal insults. I was using a water tower as an analogy (look it up). As I said, the pump is above the oil and will, as Star down under said pump at the same pressure until it runs out of oil. There is negligible head of oil in a sump.
Windage stays the same acting in a reduced volume of space.Wich means higher crankcase pressure which the crankcase ventilation system isn’t designed for.Which also means the equivalent higher crankcase pressure acting on the oil in the sump.
Thereby also at the oil seals and at the inlet side of the pump.
Feel free to put an extra few litres or a gallon of oil in over the full mark for luck.
The effects of an excessively high oil level in the sump is not in question.
What is being discussed is exactly how these effects are caused.
Your proposition, that these effects are caused by windage, is a reasonable proposition. It MAY even be correct. Or it MAY be a complete load of bull.
Suggesting that overfilling the sump will prove you correct is also bull. It will cause what we know will happen to happen, but it won’t prove any proposition, because we still have no way of showing what the actual route of failure was.
Simon:
The effects of an excessively high oil level in the sump is not in question.
What is being discussed is exactly how these effects are caused.
Your proposition, that these effects are caused by windage, is a reasonable proposition. It MAY even be correct. Or it MAY be a complete load of bull.
Suggesting that overfilling the sump will prove you correct is also bull. It will cause what we know will happen to happen, but it won’t prove any proposition, because we still have no way of showing what the actual route of failure was.
If we’re agreed that throwing an extra gallon or make it two, of oil in over the full mark for luck will probably blow an oil seal/seals, what else would have changed other than the decreased volume of the crankcase/sump caused by the higher oil level ?.
Resulting in a higher crankcase pressure which is the result of the same windage, admittedly combined with the normal amount of piston ring blow by, as before.
Carryfast:
Feel free to put an extra few litres or a gallon of oil in over the full mark for luck.
What an idiotic suggestion.
The entire post is rubbish, postulation and baffle them with bull ■■■■, in an attempt to establish a belief of higher knowledge. You are not an engineer, not even a tradesman, you failed to complete your apprenticeship.
Carryfast:
If we’re agreed that throwing an extra gallon or make it two, of oil in over the full mark for luck will probably blow an oil seal/seals, what else would have changed other than the decreased volume of the crankcase/sump caused by the higher oil level ?.
Resulting in a higher crankcase pressure which is the result of the same windage, admittedly combined with the normal amount of piston ring blow by, as before.
Yet again, you are saying that overfilling the sump, which we all know will cause problems, is caused by windage.
Crankcases have large volume breathers. What makes you so certain that these breathers cannot keep up with pressure created by windage?
Windage pressure is caused by a piston descending in its cylinder, correct?
At the same time as that piston is descending, another is rising. This is a simultaneous rise and fall, so one negates the other.
It doesn’t matter if it’s a 4 or 6 cylinder straight block, or a V8, or any other layout. Every engine has 1 piston on its power stroke, and simultaneously, another piston on its compression stroke. This is entirely deliberate, it helps in keeping the crankshaft balanced.
In a 4 potter, the other 2 pistons are on their exhaust and induction strokes, also rising and falling simultaneously. So over the whole volume of the crankcase, everything remains equal.
The only difference is that engine oil has reduced the free air volume. It is not given that this reduced free air volume will result in higher crankcase pressure caused by windage.
Simon:
Windage pressure is caused by a piston descending in its cylinder, correct?
At the same time as that piston is descending, another is rising. This is a simultaneous rise and fall, so one negates the other.
ISo over the whole volume of the crankcase, everything remains equal.
You seem to be contradicting yourself.
Either you agree that windage ( contributes ) to and creates a net crankcase pressure.Or it doesn’t.
You’re obviously actually saying that windage is a myth it doesn’t exist.
If you’re saying that higher crankcase pressure, which is a function of windage combined with blowby, resulting from the decreased sump area, created by the over fill, isn’t the issue,
then let’s hear your own reasons for over filling causing blown seals or not.
adam277:
I like how no matter how simple the question is there is never an agreement on this forum.
Or possibly agreement but for differing reasons.Its obviously not a simple question in that regard.
But probably safe to say that too much oil in the sump means less capacity in the crankcase resulting in higher crankcase pressure however it’s caused whether blow by or windage or combination of both.
corij:
i had an engine the oil level used to climb a bit over time. Probably was worn injectors
No, it wasn’t worn injectors.
Injectors are a bit like spark plugs. They inject into the cylinders. Any excess is returned to the fuel tank via their return pipes.
There is nowhere else for the fuel to go. It can’t go directly from worn injectors to sump, there is no pathway.
And the injector pump was a completely separate unit, so no pathway there either.
If you had diesel getting into the engine oil, it had to be going past the piston rings. That your oil level was climbing slowly also suggests that.
Diesel is injected into the cylinder a bit before Top Dead Centre. The piston is still rising at injection point. It continues rising and compressing the fuel/air mix. The top of the piston is shaped to maximise swirl, created by this compression, in order to further mix the fuel throughout the compressing air. This gives a better, more efficient burn, when the compression reaches ignition pressure.
Because of the microsecond of delay between injection and ignition, that gives time for (air and) fuel to pass worn rings (and soot, after ignition). That is why your oil level was slowly climbing.
I suspect Corij is referring to an injector sleeve problem which could actually allow diesel in to the sump .
Also recently I’ve had engine oil leaking out of the steering box adjuster dust cover .
Simon:
Windage pressure is caused by a piston descending in its cylinder, correct?
At the same time as that piston is descending, another is rising. This is a simultaneous rise and fall, so one negates the other.
ISo over the whole volume of the crankcase, everything remains equal.
You seem to be contradicting yourself.
Either you agree that windage ( contributes ) to and creates a net crankcase pressure.Or it doesn’t.
You’re obviously actually saying that windage is a myth it doesn’t exist.
If you’re saying that higher crankcase pressure, which is a function of windage combined with blowby, resulting from the decreased sump area, created by the over fill, isn’t the issue,
then let’s hear your own reasons for over filling causing blown seals or not.
Let me break it down to lines you can understand then.
Firstly. Is what you are calling ‘windage’ caused by a piston descending in its cylinder ?
Simon:
Windage pressure is caused by a piston descending in its cylinder, correct?
At the same time as that piston is descending, another is rising. This is a simultaneous rise and fall, so one negates the other.
ISo over the whole volume of the crankcase, everything remains equal.
You seem to be contradicting yourself.
Either you agree that windage ( contributes ) to and creates a net crankcase pressure.Or it doesn’t.
You’re obviously actually saying that windage is a myth it doesn’t exist.
If you’re saying that higher crankcase pressure, which is a function of windage combined with blowby, resulting from the decreased sump area, created by the over fill, isn’t the issue,
then let’s hear your own reasons for over filling causing blown seals or not.
CF seems to have got himself onto a US site about high performance engine tuning*.
The pressures in a diesel truck engine crankcase, compared to the atmosphere;
are very different to the pressures inside the crankcase, comparing one cylinder to another.
Others should not fall into a potential trap of looking at “pressures” whether in the crankcase as a whole, or in momentarily, in differing areas of the crankcase, and confuse them at all with what may be displayed on an oil pressure gauge.
Dipsticks and level gauges have a “high” and a “low” mark.
A slight difference over or under is not good.
A major difference over or under is very bad.
If in any doubt, check.
Just a guess. It seems one explanation for his posts?
Simon:
Let me break it down to lines you can understand then.
Firstly. Is what you are calling ‘windage’ caused by a piston descending in its cylinder ?
Obviously and to my knowledge ( which may be wrong ) creating a net increase in crankcase pressure.
Notwithstanding the question as to whether that ( contributes to creating ) a net increase in crankcase pressure my point is that an overfilled sump reduces crankcase volume.
Thereby increasing crankcase pressures which are an unarguable fact or we wouldn’t need a crankcase breather system.
So are you saying that an extra gallon or more in the sump above the full mark will blow the oil seals or not ?.
If you’re saying it will why ?.
Simon:
Let me break it down to lines you can understand then.
Firstly. Is what you are calling ‘windage’ caused by a piston descending in its cylinder ?
Obviously and to my knowledge ( which may be wrong ) creating a net increase in crankcase pressure.
Notwithstanding the question as to whether that ( contributes to creating ) a net increase in crankcase pressure my point is that an overfilled sump reduces crankcase volume.
Thereby increasing crankcase pressures which are an unarguable fact or we wouldn’t need a crankcase breather system.
So are you saying that an extra gallon or more in the sump above the full mark will blow the oil seals or not ?.
If you’re saying it will why ?.
All that was required was a simple yes or no.
5 lines of verbiage to say yes or no is entirely unnecessary.
Secondly. Do you agree that another piston will be ascending in its cylinder, exactly mirroring the descending piston?
The possible answers are either ‘Yes’ or ‘No’. Any other verbiage will be ignored.
We are attempting to establish some agreed facts here, before going any further.
Simon:
I’ll stop right there, to avoid confusing you.
peterm:
Good luck with that, Simon.
Ah, well…
Carryfast:
Obviously and to my knowledge ( which may be wrong ) creating a net increase in crankcase pressure.
Simon:
Do you agree that another piston will be ascending in its cylinder, exactly mirroring the descending piston?
In truck engines, Simon seems quite correct to me.
(Aside:
Many older twin cylinder motorcycle motorcycle and other engines, had the 2 pistons travelling in the same direction, so the firing was more evenly spread, other newer ones do have the pistons, (the crank throw) 180deg out. This gives a better dynamic balance, and a constant crankcase volume, (as one piston goes up, one goes down) but the firing is not evenly spaced. A lot about this on m/c sites.)
There is “windage” between different bores inside the crankcase, and indeed if the oil level was so very high as to reach the bottom of the bore, I can imagine it would be potentially catastrophic.
In normal use there is no piston induced windage or pressure between the crank case and atmosphere. There is a positive crankcase pressure inside the crankcase, but this isn`t to do with the changing net volume of “air” in the crankcase. (ed to add) The volume inside the crankcase remains the same, as Simon has said: the rise of one piston conteracts the fall of another.
CF: in your hypothesis you talk a lot of an increase in pressure as a piston descends into the crankcase, yet you totally ignore the decrease in pressure as that same piston rises!
Franglais:
(Aside:
Many older twin cylinder motorcycle motorcycle and other engines, had the 2 pistons travelling in the same direction, so the firing was more evenly spread, other newer ones do have the pistons, (the crank throw) 180deg out. This gives a better dynamic balance, and a constant crankcase volume, (as one piston goes up, one goes down) but the firing is not evenly spaced. A lot about this on m/c sites.)
I know a little bit about that. I ride an '81 Honda CB900F, known as the Bol D’Or or SuperSport, depending on which marketing area it was originally sold in.
The crank bearing support webs descend below normal oil level. This means the ‘windage’ is forced through the oil, for every stroke. They red-line at 9500 rpm. A race engineer in New Zealand realized that this created problems, causing the oil to froth. So he experimented with cutting windows through the webs, above the crank. A 1" square window, cut between pots 1&2 and 3&4 because those are the pairings, not only reduced frothing considerably, it also released another 10 bhp. That’s a significant bhp increase for an 80 bhp engine
The CB-Fs were quite experimental engines, in their time. They had several innovative ‘advances’ over the previous generation single overhead cam engines. Most were successful, some less so. The charging system was one system that was only ever used on the 80s F (and C) bikes. (The C’s were shaft drive cruisers which utilized the same engine design.)
Franglais:
(Aside:
Many older twin cylinder motorcycle motorcycle and other engines, had the 2 pistons travelling in the same direction, so the firing was more evenly spread, other newer ones do have the pistons, (the crank throw) 180deg out. This gives a better dynamic balance, and a constant crankcase volume, (as one piston goes up, one goes down) but the firing is not evenly spaced. A lot about this on m/c sites.)
I know a little bit about that. I ride an '81 Honda CB900F, known as the Bol D’Or or SuperSport, depending on which marketing area it was originally sold in.
The crank bearing support webs descend below normal oil level. This means the ‘windage’ is forced through the oil, for every stroke. They red-line at 9500 rpm. A race engineer in New Zealand realized that this created problems, causing the oil to froth. So he experimented with cutting windows through the webs, above the crank. A 1" square window, cut between pots 1&2 and 3&4 because those are the pairings, not only reduced frothing considerably, it also released another 10 bhp. That’s a significant bhp increase for an 80 bhp engine
The CB-Fs were quite experimental engines, in their time. They had several innovative ‘advances’ over the previous generation single overhead cam engines. Most were successful, some less so. The charging system was one system that was only ever used on the 80s F (and C) bikes. (The C’s were shaft drive cruisers which utilized the same engine design.)
Franglais:
(Aside:
Many older twin cylinder motorcycle motorcycle and other engines, had the 2 pistons travelling in the same direction, so the firing was more evenly spread, other newer ones do have the pistons, (the crank throw) 180deg out. This gives a better dynamic balance, and a constant crankcase volume, (as one piston goes up, one goes down) but the firing is not evenly spaced. A lot about this on m/c sites.)
I know a little bit about that. I ride an '81 Honda CB900F, known as the Bol D’Or or SuperSport, depending on which marketing area it was originally sold in.
The crank bearing support webs descend below normal oil level. This means the ‘windage’ is forced through the oil, for every stroke. They red-line at 9500 rpm. A race engineer in New Zealand realized that this created problems, causing the oil to froth. So he experimented with cutting windows through the webs, above the crank. A 1" square window, cut between pots 1&2 and 3&4 because those are the pairings, not only reduced frothing considerably, it also released another 10 bhp. That’s a significant bhp increase for an 80 bhp engine
The CB-Fs were quite experimental engines, in their time. They had several innovative ‘advances’ over the previous generation single overhead cam engines. Most were successful, some less so. The charging system was one system that was only ever used on the 80s F (and C) bikes. (The C’s were shaft drive cruisers which utilized the same engine design.)
I won`t say “dry sump”…
Oooppss!
Erm, no!
The single over head cam K’s from the 70s were dry sump though.
You didn’t break one, forgetting it wasn’t dry sump did you?
Carryfast:
Thereby increasing crankcase pressures which are an unarguable fact or we wouldn’t need a crankcase breather system.
Positive crankcase pressure is a result of small amounts of leakage past the piston rings, not “windage” due to pistons moving up and down.
That’s why we have crankcase breather systems, and why such systems give problems when the bores/rings are worn.
As has already been said, in any 4 or 6 cylinder in line engine the crankcase gas displaced by a downward moving piston is at all times exactly balanced out by another piston moving upwards at the same time, leaving a net zero effect on crankcase pressure.
You didn’t break one, forgetting it wasn’t dry sump did you?