Any Fluid Dynamics Experts?

neilly said:

I reckon it is time to stop taking things apart,

write a list of what the issue is.
write a list of what you have checked.
write a list of ehat you have changed.

and go from there.

Cheers

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Or, take to the drink.

lynall said:

How much oil is in the sump? not what it says on the dipstick but actual quantity, remember quoted figures are for a dry fill.
Where are the cartridges you are using coming from?
Have you got a pic of your engine bay?

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When I summon the motivation to take the sump off I think I'll pour the oil I've drained out of it back in to see where it gets to.

neilly said:

I reckon it is time to stop taking things apart,

write a list of what the issue is.
write a list of what you have checked.
write a list of ehat you have changed.

and go from there.

Cheers

Click to expand...

It's worth a go mate, I've tried everything else

Al2O3 said:

It's worth a go mate, I've tried everything else

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One of the mantras I try to use at work.

"Back to basics."

It hopefully will rule out the silly issues. Good luck.

Cheers

neilly said:

One of the mantras I try to use at work.

"Back to basics."

It hopefully will rule out the silly issues. Good luck.

Cheers

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Cheers.
Despite the new and original return pipe, it must still be something to do with that.
Feck knows, so more red wine and Guinness needed tonight

Wimblowdriver said:

I did study fluid mechanics when I did my engineering qualifications many moons ago. A very clever bloke called Bernoullie (I think I spelled that right) worked out that the volume (quantity) of a fluid flowing through a closed system was constant (ie the volume going in at one end is always the same as the volume coming out the other end). In sections of larger diameter (or cross section) the velocity falls but the pressure increases. In sections of smaller diameter the pressure falls and the velocity increases. Where the fluid exits the system (such as at the end of a hose pipe) the velocity again increases and the pressure falls to zero. People often misunderstand and mistake high velocity for high pressure, this is not the case.
In the case of your oil pipe, if the diameter is smaller than it should be then the pressure in it will be lower than it should be but the velocity through it will be increased. If you fit a larger diameter oil pipe the pressure inside it will increase and the velocity in it will fall.

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This is why a venturi works, by the way!

Could it be a faulty cyclone breather?

@Al2O3 , if too much oil in turbo and i/c cct then it's going to be one of the following due to 1. increased oil in head, 2. too much oil in system, 3. restricted oil return :.

1. recheck engine oil qty [drain and refill, minus filter volume]
2. check engine oil cooler failure - is coolant getting into oil cct :. increasing engine oil volume??
3. I won't mention Britannica Mike's video
4. breather restriction/blockage - strip out and recheck the breather system - if all good, re-install but to a catch tank - this will allow turbo and i/c system to clear itself and enable you to check the change in exhaust smoke [you must have been getting black/grey smoke from exhaust]
5. Oil let by from worn oil control rings - this from poor install/not bedding in engine/wrong oil control rings fitted

Q?? is there oil in the air intake filter and housing ??

Personally, I'd start with the breather system, oil cooler and recheck the brake servo for hidden failure. But complete the testing with a catch tank as this show how much oil is reaching head/not condensing back to sump.

ps if you get really stuck, email Britannica Mike...he's often helped out others with difficult to trace faults and you could always make a suitable donation to him for his time

+ here's an interesting rocker cover/breather note from Mike @ 11.08...and an utterly stupid Land Rover design

turrican said:

Could it be a faulty cyclone breather?

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I've already replaced that, but really appreciate the suggestion.

v8250 said:

@Al2O3 , if too much oil in turbo and i/c cct then it's going to be one of the following due to 1. increased oil in head, 2. too much oil in system, 3. restricted oil return :.

1. recheck engine oil qty [drain and refill, minus filter volume]
2. check engine oil cooler failure - is coolant getting into oil cct :. increasing engine oil volume??
3. I won't mention Britannica Mike's video
4. breather restriction/blockage - strip out and recheck the breather system - if all good, re-install but to a catch tank - this will allow turbo and i/c system to clear itself and enable you to check the change in exhaust smoke [you must have been getting black/grey smoke from exhaust]
5. Oil let by from worn oil control rings - this from poor install/not bedding in engine/wrong oil control rings fitted

Q?? is there oil in the air intake filter and housing ??

Personally, I'd start with the breather system, oil cooler and recheck the brake servo for hidden failure. But complete the testing with a catch tank as this show how much oil is reaching head/not condensing back to sump.

ps if you get really stuck, email Britannica Mike...he's often helped out others with difficult to trace faults and you could always make a suitable donation to him for his time

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Cheers, v825. Yes, I agree with your three possibles.
I don't think there is an issue with oil quantity. There is no coolant leaking in to the oil. It was about 4 years ago that I rebuilt the engine and I've changed the oil many times over that period and it looks fine with the expected amount coming out and going back in.
I've had a catch tank set up many times and nothing ever comes out of the breather. Given the amount coming out of the turbo, if it was coming via the breather first it would be very obvious.
Obviously the pistons and rings were new at the point of the rebuild. I've since had the head off , sump off and taken the pistons back out to check all was well with the pistons and rings and put it all back together. For the initial rebuild, when the engine was rebored, I had the head tested and cleaned. They replaced the exhaust valve guides and said the inlet guides were within tolerances. When I had the head off the next time I had the inlet guides replaced too.

There is no oil in the air filter.

I think I will watch Britannica Mike's video again.

I think my next move is to take the sump off and have a look at the oil return hole from inside.

Many thanks for spending time thinking about this and typing out the post.

I've watched Britannica Mike's video again and I'm pretty sure the catch can test would identify that problem. I've replaced the servo reasonably recently too, can't exactly remember when I think since I rebuilt the engine, so within 4 years. That was because the brakes weren't good though. I know the vac pumps themselves can fail, causing the same problem, and my vac pump is the original one! But surely the catch can test would identify that too. I pretty sure I'm not getting any crankcase and so rocker cover pressure at all.

So, time to drop the sump off me thinks.

@Al2O3 , a curved ball thought here, could the turbo oil return pipe be blocked or the hose be collapsed internally??

v8250 said:

@Al2O3 , a curved ball thought here, could the turbo oil return pipe be blocked or the hose be collapsed internally??

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I think that has been a problem with the aftermarket return hoses I've been using. I now have a new LR original return hose on.

Ok, didn't warm the engine so the oil is trickling out of the sump. I've got one of the valve connectors on the sump that you screw a pipe too. I've taken all the bolts out of the sump bar 4. Need to take dog out and then go to check squirrel traps so I'm going to have to wait until tomorrow
In the meantime here's another mystery. What do you think this is. Dropped out from behind engine as I was connecting the sump drain pipe.

I've no idea, will have to get torch down the back tomorrow

Fell out of engine...or from behind engine. Whatever it is...it's f**ked

v8250 said:

Fell out of engine...or from behind engine. Whatever it is...it's f**ked

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Ha ha, makes you wonder with my luck

After the rain stopped I got the sump off.
I've put an allen key though the turbo oil return union hole.


I don't know what I was hoping for, or expecting, but it's totally clear.


So, with an original return pipe that fits well and no other obstructions the oil must be able to flow back in to the sump without hindrance.



This is how much oil came out when I drained it, which is standard for every service.
The full line on the dipstick is quite a few inches below the oil return inlet hole, so there would have to be a hell of a lot of oil in the sump and bottom of the block before it began to hinder the return oil coming in.

I think this leaves me with either the turbo oil inlet pressure is too high or there is oil coming through the cyclone breather I've done the catch can test several times and there's nothing coming out. However, what I've thinking is that when the vent pipe is in the catch can it's not got the fierce draw on it from the air intake. So, maybe there is an issue with the vac pump/servo As the servo is new(ish) and the vac pump is the original I'm wondering if the vac pump has the issue in itself that causes it to keep pumping in to the block. Maybe this pressure is low enough to not push oil through the cyclone breather on it's own. But, maybe the bit of pressure from the vac pump combined with the draw from the turbo and engine is enough to draw oil through?
I can't remember if I've done the turbo outlet on to the wing test when the cyclone breather tube is disconnected? I'll have to go through my engine rebuild thread to see if I've mentioned doing that.
@jamesmartin I think I've got a vague recollection of you saying that the air being pulled through the air intake pipe doesn't create any suction on the cyclone breather pipe. Is that right? If so my proposed test will be a waste of time.

Sump took some getting off, I'd done a great job with the RTV when I put it on

Al2O3 said:

After the rain stopped I got the sump off.
I've put an allen key though the turbo oil return union hole.
View attachment 231587

I don't know what I was hoping for, or expecting, but it's totally clear.
View attachment 231589

So, with an original return pipe that fits well and no other obstructions the oil must be able to flow back in to the sump without hindrance.

View attachment 231590

This is how much oil came out when I drained it, which is standard for every service.
The full line on the dipstick is quite a few inches below the oil return inlet hole, so there would have to be a hell of a lot of oil in the sump and bottom of the block before it began to hinder the return oil coming in.

I think this leaves me with either the turbo oil inlet pressure is too high or there is oil coming through the cyclone breather I've done the catch can test several times and there's nothing coming out. However, what I've thinking is that when the vent pipe is in the catch can it's not got the fierce draw on it from the air intake. So, maybe there is an issue with the vac pump/servo As the servo is new(ish) and the vac pump is the original I'm wondering if the vac pump has the issue in itself that causes it to keep pumping in to the block. Maybe this pressure is low enough to not push oil through the cyclone breather on it's own. But, maybe the bit of pressure from the vac pump combined with the draw from the turbo and engine is enough to draw oil through?
I can't remember if I've done the turbo outlet on to the wing test when the cyclone breather tube is disconnected? I'll have to go through my engine rebuild thread to see if I've mentioned doing that.
@jamesmartin I think I've got a vague recollection of you saying that the air being pulled through the air intake pipe doesn't create any suction on the cyclone breather pipe. Is that right? If so my proposed test will be a waste of time.

Sump took some getting off, I'd done a great job with the RTV when I put it on

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the breather pipe been on the suction side of turbo will create a draw on the breather

jamesmartin said:

the breather pipe been on the suction side of turbo will create a draw on the breather

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Get in!
Do you think it's possible that a combined vac pump issue (or servo as in Britannica mikes video) and the suction on the breather might be the problem?

Al2O3 said:

Get in!
Do you think it's possible that a combined vac pump issue (or servo as in Britannica mikes video) and the suction on the breather might be the problem?

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if you were pressurising the block youd notice when you removed cap or with your removed breather pipe, if youve removed the breather pipe from the intake and still pass oil its the turbo