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Hardware
 


Member Since: 28 Jun 2016
Location: Hiding under the M60
Posts: 12676

United Kingdom 2011 Discovery 4 3.0 SDV6 XS Auto Sumatra BlackDiscovery 4

lynalldiscovery wrote:
Hardware17 wrote:
well … the physics of it is blah blah


Thanks, but I realise that ...


Sorry, didn't mean to be patronising but I can tell not everyone gets the basics … the "Land Rover turning drivers into mechanics since 1947" thing is less and less the case. Whilst many on here know one end of a wrench from the other, LR's market is aimed less and less at them.

As for tabs/tags/tangs stopping rotation … why wouldn't they ? it's clearly (assuming tab sticks outwards in a clockwise manner and relative movement of the parts produces a clockwise frictional force then the tab is clearly going to stop rotation until the forces are enough to flatten/rip it off. or am I missing something ?
  
Post #201919616th Jan 2019 7:35 pm
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DiscoJeffster
 


Member Since: 27 Feb 2016
Location: Perth
Posts: 204

Australia 2010 Discovery 4 3.0 TDV6 HSE Auto Nara BronzeDiscovery 4

Yes, a tang will stop it moving, until it fails and grabs, but that’s a presumption that the reason the engine fails is the bearing gently moving on its own which then leads to the failure. This is not the case. Has anyone here ever built an engine? Anyone installed bearings? If you had you’d know that there is no way a bearing will move under normal operation, tang or not. They are shaped such that they literally snap into place and the bearing tension keeps them stable.

Tangs were designed to simplify manual assembly by ensuring correct alignment of the bearing and the oil channel, not long term bearing position control. Modern assembly practice has made the tang redundant.

If believe these engines have a fundamental flaw yet disclosed publicly that causes the crank failure. Whether a bearing lets go through oil starvation destroying the crank or the crank goes first I’m not sure, but a tang on a bearing isn’t going to resolve it
  
Post #201929517th Jan 2019 12:38 am
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Bardley
 


Member Since: 02 May 2018
Location: Hertfordshire
Posts: 437

United Kingdom 2011 Discovery 4 3.0 TDV6 HSE Auto Santorini BlackDiscovery 4

As above, There is clearly a thought that the shells sit in the crank and will readily rotate to block oil ways.
Having rebuilt alot of engines of all sizes, there is no way that they will rotate on there own accord. Put that one to bed.
The failed engine threads really shouldn't be titled 'Snapped Crank', as this is misleading, and Is highly likely to be a fault elsewhere that has manifested as a catastrophic fail of the Crank.

All has been said before I know.. but heavens, they aren't all failing, and we tend to only hear of the poor unfortunates that have the problem, and this then sounds like everyone is on borrowed time.

Previous posts from Oval makes interesting reading, and it finally seems there is a path to getting to the bottom of the issue in engineering terms. If this happens, then members can then start to get a preventative measure in place.
In the meantime, regular oil/filter and TLC would be my advice.
 2011 MY D4 HSE
Previously 2001 D2 TD5, 1996 D1 300Tdi, 1985 90 2.2 petrol.
Bikes! KTM, BMW, British, Classics and others.
 
 
Post #201930517th Jan 2019 7:56 am
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OvalAutos
 


Member Since: 28 Dec 2018
Location: Cradley Heath
Posts: 382

United Kingdom 

lynalldiscovery wrote:
Hardware17 wrote:
well … the physics of it is that they spin when the friction between the moving bits and the bearing is greater than the forces keeping the bearing in place. usual suspect for this would be oil starvation.

But the interesting thing, from Ovalautos various posts is that even tabbed ones move. Notice it's "move" he uses and not "spin".

Is the implication they move sideways ? or is he saying they rotate a bit rather than spin freely ? (which might be how some would interpret "spin" )

I was also surprised to learn that in some racing engines, they are screwed in place !! I though that would not work as the screw would expand and score the crank … but would that matter ? the scored section would simply hold more oil, would it not ?


Thanks, but I realise that and was interested to hear ovalautos take on it, ie from someone who sees inside them daily, so should be genned up with the latest info?

I have posted before and I reckon its in the cars history, ie its had abuse some time in the past and now its come back to bite the current owner big time.
Thinking along the lines of wrong spec oil, short term overheat ie blown hose, leaking injector contaminating the engine oil etc


I've had a 1 owner car in with a destroyed engine at 40k miles and dealer serviced. Knowing the owner, I can honestly say they go around like 'driving Miss Daisy', let the car warmup before driving and use the premium diesel.

At the same time, I've had a farmers D3 with 170k on the clock still going strong. He uses like a tank, pull tractors and chucks red diesel in. Its last service was 3yrs ago and came to us for its first belt change. The oil (4ltrs) that came out was like tar. The belt was cracked and missing teeth.
But guess what; runs and sounds like a new engine.

So go figure, because I think it is pot luck Rolling Eyes
 Joe  
Post #201931317th Jan 2019 8:22 am
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OvalAutos
 


Member Since: 28 Dec 2018
Location: Cradley Heath
Posts: 382

United Kingdom 

L319 wrote:
I always thought the tags were to position the shells correctly rather than to stop spinning. If its going to pick up it will go. I had an ex army land Rover in the 1970's that the tangs hadn't been lined up with cut outs when assembled by the REME and it ran OK. They were just flattened as though they didn't exist


Correct. Tags are for location purposes only.
 Joe  
Post #201931517th Jan 2019 8:23 am
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Bardley
 


Member Since: 02 May 2018
Location: Hertfordshire
Posts: 437

United Kingdom 2011 Discovery 4 3.0 TDV6 HSE Auto Santorini BlackDiscovery 4
Faith

I've had a 1 owner car in with a destroyed engine at 40k miles and dealer serviced. Knowing the owner, I can honestly say they go around like 'driving Miss Daisy', let the car warmup before driving and use the premium diesel.

At the same time, I've had a farmers D3 with 170k on the clock still going strong. He uses like a tank, pull tractors and chucks red diesel in. Its last service was 3yrs ago and came to us for its first belt change. The oil (4ltrs) that came out was like tar. The belt was cracked and missing teeth.
But guess what; runs and sounds like a new engine.




I like hearing this as it restores a little faith when it's easy to drive around thinking it's all going to go wrong soon...
 2011 MY D4 HSE
Previously 2001 D2 TD5, 1996 D1 300Tdi, 1985 90 2.2 petrol.
Bikes! KTM, BMW, British, Classics and others.
 
 
Post #201933217th Jan 2019 9:22 am
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DSL
Keeper of the wheelie bin 


Member Since: 11 May 2006
Location: Off again! :-)
Posts: 72740

Ukraine 

It’s all a complete lottery, one I’m glad I’m no longer playing. Thumbs Up
   
Post #201933417th Jan 2019 9:26 am
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robpenrose
 


Member Since: 12 Jan 2016
Location: Surrey / SW London
Posts: 2136

United Kingdom 2010 Discovery 4 3.0 TDV6 HSE Auto Stornoway GreyDiscovery 4

pussy Rolling with laughter
 

Current: D4 HSE
Previous: BMW Z4M Coupe
Previous: Land Rover Defender 90 CSW Td5
Previous: Land Rover Discovery Td5 ES 
 
Post #201933917th Jan 2019 9:45 am
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DSL
Keeper of the wheelie bin 


Member Since: 11 May 2006
Location: Off again! :-)
Posts: 72740

Ukraine 

Absatidellingtootlie. Thumbs Up

Rolling with laughter Rolling with laughter
   
Post #201934317th Jan 2019 9:50 am
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lynalldiscovery
 


Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274

United Kingdom 2006 Discovery 3 TDV6 Metropolis LE Auto Bonatti GreyDiscovery 3

OvalAutos wrote:
lynalldiscovery wrote:
Hardware17 wrote:
well … the physics of it is that they spin when the friction between the moving bits and the bearing is greater than the forces keeping the bearing in place. usual suspect for this would be oil starvation.

But the interesting thing, from Ovalautos various posts is that even tabbed ones move. Notice it's "move" he uses and not "spin".

Is the implication they move sideways ? or is he saying they rotate a bit rather than spin freely ? (which might be how some would interpret "spin" )

I was also surprised to learn that in some racing engines, they are screwed in place !! I though that would not work as the screw would expand and score the crank … but would that matter ? the scored section would simply hold more oil, would it not ?


Thanks, but I realise that and was interested to hear ovalautos take on it, ie from someone who sees inside them daily, so should be genned up with the latest info?

I have posted before and I reckon its in the cars history, ie its had abuse some time in the past and now its come back to bite the current owner big time.
Thinking along the lines of wrong spec oil, short term overheat ie blown hose, leaking injector contaminating the engine oil etc


I've had a 1 owner car in with a destroyed engine at 40k miles and dealer serviced. Knowing the owner, I can honestly say they go around like 'driving Miss Daisy', let the car warmup before driving and use the premium diesel.

At the same time, I've had a farmers D3 with 170k on the clock still going strong. He uses like a tank, pull tractors and chucks red diesel in. Its last service was 3yrs ago and came to us for its first belt change. The oil (4ltrs) that came out was like tar. The belt was cracked and missing teeth.
But guess what; runs and sounds like a new engine.

So go figure, because I think it is pot luck Rolling Eyes


Ive worked at a dealers and can assure anyone reading this, FMDSH it dont mean squat!
You will pay top dollar and out the back they will have the lads/apprencitces changing your oil.

Heres a story, not on a car but on a truck, oil drained filters changed, engine started and allowed to idle as they gossiped until it seized as they forgot to put the oil in, they let it cool down, stuck oil in it and off it went!
Many many more just like that.
  
Post #201944917th Jan 2019 4:41 pm
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lynalldiscovery
 


Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274

United Kingdom 2006 Discovery 3 TDV6 Metropolis LE Auto Bonatti GreyDiscovery 3

Hardware17 wrote:
lynalldiscovery wrote:
Hardware17 wrote:
well … the physics of it is blah blah


Thanks, but I realise that ...


Sorry, didn't mean to be patronising but I can tell not everyone gets the basics … the "Land Rover turning drivers into mechanics since 1947" thing is less and less the case. Whilst many on here know one end of a wrench from the other, LR's market is aimed less and less at them.

As for tabs/tags/tangs stopping rotation … why wouldn't they ? it's clearly (assuming tab sticks outwards in a clockwise manner and relative movement of the parts produces a clockwise frictional force then the tab is clearly going to stop rotation until the forces are enough to flatten/rip it off. or am I missing something ?


No worries I didnt take it as patronising Thumbs Up
Thats the problem with the written word, you cannot hear the tone of the voice.
  
Post #201945017th Jan 2019 4:43 pm
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