D3 spun bearings video

[Bohica]

A video from LR Time.
Is this the end? Complete engine failure - Land Rover Discovery 3 / LR3 - YouTube (https://www.youtube.com/watch?v=MKYovvWWym0)

[BradC]

Why do 2.7 cranks break? (https://www.aulro.com/afvb/l319-discovery-3-and-4-a/288338-why-do-2-7-cranks-break-post3116343.html#post3116343)

[350RRC]

In the vid, bearings have spun, he says something like the block has spread as he takes out the centre caps over the offending mains and then he's just going to line bore it?

The next vid will be interesting. Great stuff.

DL

[loanrangie]

I am amazed that the bearings don't have tabs that locate in a notch to stop them from rotating, every motor I have pulled down has then.

[PeterOZ]

she is at least rather cute and amusing. Funny little quips.

[shanegtr]

I am amazed that the bearings don't have tabs that locate in a notch to stop them from rotating, every motor I have pulled down has then.
They are really only for assembly and do bugger all in preventing a spun bearing. The bore itself should be providing enough friction to prevent the rotation if the sizings are correct. Dont under estimate the power of friction - I've worked on turbines in the 2-5gigawatt power range and the drive couplings are simply friction fit taper - there is no drive keyways, splines etc

[loanrangie]

They are really only for assembly and do bugger all in preventing a spun bearing. The bore itself should be providing enough friction to prevent the rotation if the sizings are correct. Dont under estimate the power of friction - I've worked on turbines in the 2-5gigawatt power range and the drive couplings are simply friction fit taper - there is no drive keyways, splines etc

I disagree, the tabs are on opposite sides and prevent them from spinning 100%, sure they aid in assembly but will also prevent them moving.

[DiscoJeffster]

They are really only for assembly and do bugger all in preventing a spun bearing. The bore itself should be providing enough friction to prevent the rotation if the sizings are correct. Dont under estimate the power of friction - I've worked on turbines in the 2-5gigawatt power range and the drive couplings are simply friction fit taper - there is no drive keyways, splines etc

My ex-Porsche GT3 had friction fit cam gears onto the cams. The power of friction didn’t help me though. During a high speed driver training event where the task was to drive with your feet flat on the floor and not touch the pedals whilst turning a corner at speed (skid pan) and maintaining within the line (learning how to let the wheel move loosely under hand and follow the undulations to avoid skipping the surface), I spun.

The engine actually ran backwards (yes this IS possible), popped the intake apart (runners connected by rubber joiners between sections) and unbeknownst to me at the time, had shifted a cam gear out of position/alignment. Not enough to cause damage, but enough that the next time I had an MOT I couldn’t pass the emissions test. £3500 later and the engine removed and Porsche Germany involved, they worked out that was what had happened and why it wouldn’t meet emissions.

Anyhow, I digressed!

[Discodicky]

They are really only for assembly and do bugger all in preventing a spun bearing. The bore itself should be providing enough friction to prevent the rotation if the sizings are correct. Dont under estimate the power of friction - I've worked on turbines in the 2-5gigawatt power range and the drive couplings are simply friction fit taper - there is no drive keyways, splines etc

Yes, but you mention a slight taper which is totally different to the crankshaft bearing/shells simply placed into the block and 'hope' they won't spin. I firmly have always felt that not having the locator tabs is the principal reason of the failures.

As you'd be aware large drill bits are tapered and that taper is the only thing that prevents turning whilst drilling the hole.

[350RRC]

I am amazed that the bearings don't have tabs that locate in a notch to stop them from rotating, every motor I have pulled down has then.

And to keep the oil holes in the shells lined up with the same in the block so the oil pump can send oil from the sump through the crank to the big end conrod bearings, etc.

DL

[josh.huber]

Yes, but you mention a slight taper which is totally different to the crankshaft bearing/shells simply placed into the block and 'hope' they won't spin. I firmly have always felt that not having the locator tabs is the principal reason of the failures.

As you'd be aware large drill bits are tapered and that taper is the only thing that prevents turning whilst drilling the hole.

In with Shane, the bearings aren't simply pushed in, they are measured for bearing crush first,
The bearing shells will have Larger outside diameter then the block and cap inside diameter. The difference is the crush. They are crush held in place.
The tabs don't do much they are tiny and weak. They are an alignment tool.
Sure I agree they do something. But a bearing with correct crush and no tab won't spin. A bearing with incorrect crush and a tab, will spin.
That being said. I also agree they should be there, just like coolant should be bright green and bond is a man

[Eric SDV6SE]

+1 Josh.

Plus the 140 NM per main cap bolt, then a 90 deg turn ensures proper crush fit of the main bearing. This then points to incorrect sized main bearing shells, plus the top halves are different to the bottom halves as perhaps one of the main contributors to spun bearings.

[PerthDisco]

The argument made in the video is this has been caused by Fabian having to crank to start for a long time due to a failing HPFP. Previous videos have followed the diagnosis and eventual replacement (twice) of the HPFP. Progressive damage caused by the oil starvation (it is alleged) was done to the bearing surface over time till it finally failed.

It also states that broken cranks follow the bearing failure and eventual seizing. This is depends on the time taken in milliseconds to minutes of the shell rotating to block oil and heat up causing the seize up varies depending on each car and what it’s doing at the time. Most seem to get caught at the death rattle stage.

This concurs with Dazza’s observations of relatively few snapped cranks when things go to poop.

Good news is that the top end is in like new condition so if oversized bearing shells are available there’s a good option

Looking forward to next video.