Any Fluid Dynamics Experts?

Al2O3 · Feb 28, 2021

lynall said:
Very very nice

Just thinking what about put turbo oil return into a pot then see if the turbo still passes oil? with and without the flex pipe.
Obviously you have limited run time as you will run out of oil but got to be worth a try?
My perhaps illogical thinking is to see if the return pipe is the issue?

I don't think that is illogical. I did consider it when I put the new CHRA in. The new oil return pipe was pretty stiff and I didn't want to force it over to fit in to a catch pot. I do have an aftermarket one I could use and not be worried about bending and permanently putting a crease in. The plastic pipe inside the pipes is rigid.
I'm going to Google oil regulators tonight. The Landy is going to sit and look pretty at the bottom of the drive until I get it sorted. Or, it might be a permanent feature at the bottom of the drive

I've got no idea if the CHRA seals can recover from oil being forced through them. It's only done about 15 miles since I put the new CHRA in, so don't want to risk running it any further. Also, I know we affectionately refer to these engines as oil burners (like chip shop oil etc) but they are not great at burning engine oil. The soot and carbon build up on the piston crowns was horrific when I took the engine apart during the last investigations. The less it's ran the better.

mick 1986 · Feb 28, 2021

Al2O3 said:
I don't think that is illogical. I did consider it when I put the new CHRA in. The new oil return pipe was pretty stiff and I didn't want to force it over to fit in to a catch pot. I do have an aftermarket one I could use and not be worried about bending and permanently putting a crease in. The plastic pipe inside the pipes is rigid.
I'm going to Google oil regulators tonight. The Landy is going to sit and look pretty at the bottom of the drive until I get it sorted. Or, it might be a permanent feature at the bottom of the drive I've got no idea if the CHRA seals can recover from oil being forced through them. It's only done about 15 miles since I put the new CHRA in, so don't want to risk running it any further. Also, I know we affectionately refer to these engines as oil burners (like chip shop oil etc) but they are not great at burning engine oil. The soot and carbon build up on the piston crowns was horrific when I took the engine apart during the last investigations. The less it's ran the better.

If that liner is hard plastic, then it’s possibly crimped from new. I would remove the return pipe, and try to fashion a way of securing it into some form of plastic bottle. Fill the bottle with oil, and then let it drain out of the pipe. That may show if the pipe is causing the oil pressure to build. Blowing through the pipe wouldn’t show it as the air would pass any restriction relatively easily.

Al2O3 · Feb 28, 2021

mick 1986 said:
If that liner is hard plastic, then it’s possibly crimped from new. I would remove the return pipe, and try to fashion a way of securing it into some form of plastic bottle. Fill the bottle with oil, and then let it drain out of the pipe. That may show if the pipe is causing the oil pressure to build. Blowing through the pipe wouldn’t show it as the air would pass any restriction relatively easily.

Obviously I've not touched this pip as it's a genuine LR one a bloody expensive. I've chopped a couple of the aftermarket ones up though and you're right, the hard rigid pipe is crimped in to the fitting at either end.

v8250 · Feb 28, 2021

I'm not sure if an oil regulator will be of use. The oil system complete [sump, block, head, breather system] should be at atmospheric relief whilst oil pressure builds with engine running; it's not a sealed system. I'd be inclined not to add a non-original component...and regulators have a habit of blocking/sticking.

Q1. Have you ran the engine with the brake master cylinder isolated and the vacuum pump output sealed up? If not, this prove the MC/leak side of the cct.
Q2. Have you thought of getting your engine tested at an engine shop that really knows Landies? Getting it thoroughly checked over...bore/cylinder pressure, head pressure/valve let-by?

Al2O3 · Feb 28, 2021

v8250 said:
I'm not sure if an oil regulator will be of use. The oil system complete [sump, block, head, breather system] should be at atmospheric relief whilst oil pressure builds with engine running; it's not a sealed system. I'd be inclined not to add a non-original component...and regulators have a habit of blocking/sticking.

Q1. Have you ran the engine with the brake master cylinder isolated and the vacuum pump output sealed up? If not, this prove the MC/leak side of the cct.
Q2. Have you thought of getting your engine tested at an engine shop that really knows Landies? Getting it thoroughly checked over...bore/cylinder pressure, head pressure/valve let-by?

Ans 1. No. But I've just ran it with the cyclone breather removed, so nothing is being pushed through there by the vac pump pressurising the engine.
Ans 2. No. But, I'm very close to admitting defeat. So putting it in to the local LR Indie is probably a very goo idea.

The thought about the regulator was that most turbos are designed to run at about 40psi. I've got about 52psi at times, so thought of giving it a go because I'm clutching at straws. Someone suggested this months and months ago on my engine rebuild thread and i dismissed it, because, as you say, it shouldn't need one. Desperate times though

mick 1986 · Feb 28, 2021

Al2O3 said:
Obviously I've not touched this pip as it's a genuine LR one a bloody expensive. I've chopped a couple of the aftermarket ones up though and you're right, the hard rigid pipe is crimped in to the fitting at either end.

If you have any of the ones chopped up, can you take some photos of the unions to pipe connections? I’m thinking we could remove all the joints from the original pipes, and be left with 2 steel pipes and unions. Then you can fit a piece of rubber oil hose between the two. You could cut it to length and secure with jubilee clips. That should completely remove any possibility of the internal bore causing the problems. Measure the diameter of the connections for the hose, I have quite a few different bores of oil hose. I will send you a few bits.

mick 1986 · Feb 28, 2021

v8250 said:
I'm not sure if an oil regulator will be of use. The oil system complete [sump, block, head, breather system] should be at atmospheric relief whilst oil pressure builds with engine running; it's not a sealed system. I'd be inclined not to add a non-original component...and regulators have a habit of blocking/sticking.
/QUOTE]

I would agree with this. We can’t all be running less than 40psi of oil pressure, so something else has to be the route cause. The original must have worked, so we need to find out what’s causing it, and fix that, not cover it up.

**** knows how I have done that with the quote, but I can’t get it sorted.

Al2O3 · Feb 28, 2021

mick 1986 said:
If you have any of the ones chopped up, can you take some photos of the unions to pipe connections? I’m thinking we could remove all the joints from the original pipes, and be left with 2 steel pipes and unions. Then you can fit a piece of rubber oil hose between the two. You could cut it to length and secure with jubilee clips. That should completely remove any possibility of the internal bore causing the problems. Measure the diameter of the connections for the hose, I have quite a few different bores of oil hose. I will send you a few bits.

Been there and tried that.

f24154c5-478d-4465-9a1e-576840d3388e-jpeg.221484

mick 1986 · Feb 28, 2021

Al2O3 said:
Been there and tried that.

Did that give the same fault? If so, that should surely prove that the return line is not at fault, well not between the turbo and sump anyway.

I’m not sure where to go next to be honest.

Edit: what is the other braided line in that photo? It has quite a kink in it.

Al2O3 · Feb 28, 2021

mick 1986 said:
Did that give the same fault? If so, that should surely prove that the return line is not at fault, well not between the turbo and sump anyway.

I’m not sure where to go next to be honest.

Edit: what is the other braided line in that photo? It has quite a kink in it.

I didn't give it a proper test to be honest. I was too worried about it not coping with the heat of the oil and the heat from the exhaust, which is extremely close to it. My set up didn't have any braided steel to protect it. That's when I sourced an original Land Rover return pipe and thought I had it cracked then. The thin braided pipe is the high pressure oil inlet pipe to the turbo. It twisted when I tightened up that time, but went back ok when I slackened it off.

Cavey_P38 · Feb 28, 2021

Hi Mate

My engine bay setup is identical
to yours.

My CHRA went in ok on Friday but didn't cure all the poor running did reduce the smoke.

Will pop a pic up tomorrow,

Feel your pain mine has been a never ending fight one problem sorted another appears.. But it is nothing compared to yours. its not so bad when you can find the problem, and attack it

keep your chin up mate, worse case we will all turn up at yours eat you out of house and home, empty your booze cabinet and swap bits between landys til we sort all our problems..

Al2O3 · Feb 28, 2021

Cavey_P38 said:
Hi Mate

My engine bay setup is identical
to yours.

My CHRA went in ok on Friday but didn't cure all the poor running did reduce the smoke.

Will pop a pic up tomorrow,

Feel your pain mine has been a never ending fight one problem sorted another appears..

If it's reduced the smoke that's a good sign that the new CHRA is delivering air to the inlet manifold better than your old one.
When I've been doing the above tests and I take the pipe off my turbo outlet and let it blast the air on to the wing. ie the engine is running in a naturally aspirated set up, it smokes horrendously especially when cold. There's obviously not enough air for the diesel to burn efficiently.

Cavey_P38 · Feb 28, 2021

yeah got mine running loads better today will stick it up on my thread. Borrowed fIP but we had 3 landys in the workshop day flew by and we got lots done and keeps you motivated or when ur stuck someone always has a different aapproach..

Al2O3 · Feb 28, 2021

Cavey_P38 said:
yeah got mine running loads better today will stick it up on my thread. Borrowed fIP but we had 3 landys in the workshop day flew by and we got lots done and keeps you motivated or when ur stuck someone always has a different aapproach..

It's looking good

When you get your FIPs back from Diesel Bob you should be sorted

Al2O3 · Mar 3, 2021

I've been comparing the aftermarket return pipe to my new genuine Land Rover one.

The aftermarket pipe has an ID of 3/8" or 11mm

The Land Rover one has an ID of 1/2" or 12.5mm

The turbo end flange fitting dimensions are the same.
So......
Aftermarket 11mm ID gives a cross sectional area of 95.03 square mm
Genuine 12.5mm ID gives a cross sectional area of 122.72 square mm

That's a 29% increase in cross sectional area and it still doesn't seem to be big enough to allow the oil to flow away quick enough without backing up.
The turbo end flange has a step in it.

I could use the dremmel to grind a radius on that to help the oil flow out?

lynall · Mar 3, 2021

Al2O3 said:
I've been comparing the aftermarket return pipe to my new genuine Land Rover one.

The aftermarket pipe has an ID of 3/8" or 11mm
View attachment 232271

The Land Rover one has an ID of 1/2" or 12.5mm
View attachment 232272

The turbo end flange fitting dimensions are the same.
So......
Aftermarket 11mm ID gives a cross sectional area of 95.03 square mm
Genuine 12.5mm ID gives a cross sectional area of 122.72 square mm

That's a 29% increase in cross sectional area and it still doesn't seem to be big enough to allow the oil to flow away quick enough without backing up.
The turbo end flange has a step in it.
View attachment 232273

I could use the dremmel to grind a radius on that to help the oil flow out?

Cannot see it making feck all difference, truck ones are not much bigger, maybe 3/4 to an inch outside dia.
Iirc you said the issue was there no matter what combo of pipes you tried?

v8250 · Mar 3, 2021

That's a big % difference is csa...but I don't think the Dremel is needed. If the retained oil volume is that much it's down to a greater system restriction or increased system pressure :. restricted return side volume flow.

Reading the TD5 engine oil route which is similar to the 200/300tdi, could the oil pressure relief valve be sticking semi-hard closed causing overall too high a pressure :. high pressure on the oil return??

v8250 · Mar 3, 2021

I've never changed a 300tdi oil pump/pressure relief valve so have watched this. How tight did you tighten up the pump pressure screw? Is it possible to overtighten, resulting in oil pressure valve not relieving? + when you rebuilt the oil pump did you dry test assemble to ensure free running + Vaseline load pump gear and chamber before final assembly?

Al2O3 · Mar 3, 2021

Guys, first of all I greatly appreciate you taking the time to think about this because I'm obviously not going to work it out myself.

Thank you!

lynall said:
Cannot see it making feck all difference, truck ones are not much bigger, maybe 3/4 to an inch outside dia.
Iirc you said the issue was there no matter what combo of pipes you tried?

I've tried different 'brands' of aftermarket oil return pipes, but non of them fitted well. When the nut on the block is tightened down, pulling that fitting square and then the flange on the turbo CHRA is bolted down, pulling that fitting square, the pipe developed a kink. Presumably enough to restrict the flow? I've now got the new (25 year old) genuine LR return pipe.

v8250 said:
That's a big % difference is csa...but I don't think the Dremel is needed. If the retained oil volume is that much it's down to a greater system restriction or increased system pressure :. restricted return side volume flow.

Reading the TD5 engine oil route which is similar to the 200/300tdi, could the oil pressure relief valve be sticking semi-hard closed causing overall too high a pressure :. high pressure on the oil return??

I thought I'd do the calculations because I know area can increase/decrease by a surprising amount when shape dimension vary a little. Even though I'm now using the genuine pipe I thought it might help to look at dimensions to try and get an idea of the effect of a small restriction. For example if there is an unnoticeable deformation of the return pipe by 1mm, so at one point in the pipe the ID is down to 11.5mm instead of 12.5mm, that reduces the cross sectional area by 16%.

If the flow through the return doesn't have much extra capacity designed in, then this might make all the difference?

A restriction in the oil return seems to be the cause of this problem, according to YouTube videos created by Turbo servicing companies. When the oil goes down that pipe it just drops in to the sump. I can't see there being any other cause of a restriction other than the pipe?

I don't know if the oil pressure relief valve sticking would affect the return oil dropping out of the end of the return pipe? When I took the sump off the last time to take the pistons out, I took the relief valve out for a look. The valve moved freely and I was surprised to find the spring had shrunk in length compared to when I put it in. (brand new genuine LR one from Turners) If anything, with a shorter spring, it should relieve pressure even sooner?

When I rebuilt the engine the new rotor looked as though it was going to work fine and yes I filled it with vaseline on assembly.

I've asked the question about inlet pipe pressure/flow being affected by aftermarket pipes and have seriously considered going down the pressure regulator route. I've shelved the idea for now based on; nobody else needs one and they can stick (apparently) starving the turbo of oil.

I've sent pictures of the return pipe fittings, with measurements on, to a pipe fittings company to see if they think it's an AN-8, AN-10 or any type of fitting they know. Rather than bodge something with jubilee clips I'm thinking I could make a decent custom return pipe with an ID nearer to 15mm to rule out a restricted return once and for all.

mick 1986 · Mar 3, 2021

Al2O3 said:
Guys, first of all I greatly appreciate you taking the time to think about this because I'm obviously not going to work it out myself. Thank you!

I've tried different 'brands' of aftermarket oil return pipes, but non of them fitted well. When the nut on the block is tightened down, pulling that fitting square and then the flange on the turbo CHRA is bolted down, pulling that fitting square, the pipe developed a kink. Presumably enough to restrict the flow? I've now got the new (25 year old) genuine LR return pipe.

I thought I'd do the calculations because I know area can increase/decrease by a surprising amount when shape dimension vary a little. Even though I'm now using the genuine pipe I thought it might help to look at dimensions to try and get an idea of the effect of a small restriction. For example if there is an unnoticeable deformation of the return pipe by 1mm, so at one point in the pipe the ID is down to 11.5mm instead of 12.5mm, that reduces the cross sectional area by 16%. If the flow through the return doesn't have much extra capacity designed in, then this might make all the difference?

A restriction in the oil return seems to be the cause of this problem, according to YouTube videos created by Turbo servicing companies. When the oil goes down that pipe it just drops in to the sump. I can't see there being any other cause of a restriction other than the pipe? I don't know if the oil pressure relief valve sticking would affect the return oil dropping out of the end of the return pipe? When I took the sump off the last time to take the pistons out, I took the relief valve out for a look. The valve moved freely and I was surprised to find the spring had shrunk in length compared to when I put it in. (brand new genuine LR one from Turners) If anything, with a shorter spring, it should relieve pressure even sooner?

When I rebuilt the engine the new rotor looked as though it was going to work fine and yes I filled it with vaseline on assembly.

I've asked the question about inlet pipe pressure/flow being affected by aftermarket pipes and have seriously considered going down the pressure regulator route. I've shelved the idea for now based on; nobody else needs one and they can stick (apparently) starving the turbo of oil.

I've sent pictures of the return pipe fittings, with measurements on, to a pipe fittings company to see if they think it's an AN-8, AN-10 or any type of fitting they know. Rather than bodge something with jubilee clips I'm thinking I could make a decent custom return pipe with an ID nearer to 15mm to rule out a restricted return once and for all.

The larger diameter will flow the oil slower, at a higher pressure. Lowering the diameter will increase the velocity, but reduce the pressure. So I don’t think increasing the diameter much is the way forward, well not at the minute anyway.

Any Fluid Dynamics Experts?

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