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Ed Poore

Armchair diagnosis: snapcrankeritis

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So you've all heard of the Land Rover disease. Well I've come down with a severe case of snapcrankeritis.

Cue 6 weeks ago and was pottering down to Wales with a pretty empty 110 and this happened.

DSC_0025.thumb.JPG.553f78dfc92a2d68ae38019414003b25.JPG

Conveniently had a friend with another 300Tdi engine sat in the yard, bit unknown origin but was running well when it came out of a wrecked Disco. So cue a busy weekend and 16h later an engine swap was done, complete with new clutch and cambelt and up running. A couple of niggles were sorted out over the next few days and she was running well.

Cue 1500 miles and 5 weeks later with a Bridgeport in tow and this happened.

DSC_0003.thumb.JPG.7b585a1c75cdac8d4ec5cd6db2bee031.JPG

So let's hear some ideas!

And contrary to popular belief I was actually driving extraordinarily gently when the second one went.

The original one rusted up while it was outside when I was skiing but I'm going to take the second to my Godmother's husband who is a metallurgist and should be able to diagnose the failure mode from looking at it.

And a huge public thanks to @GBMUD for retrieving the 110 after the first incident.

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Just bad luck I think. Remember 300's are quite old now. Let's face it my 200 snapped a cam just starting it.

Mike

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Probably no real reason down to usage, just down to time.

Most likely a small stress riser caused by or during production, or carelessness at some time during its life, and the due to the accumulation of time and miles has finally let go.

Could have happened at any time I guess, and just "one of those things"

20 years ago, myself and a workmate had driven about 100 miles in a Transit DI. We were sitting in a traffic queue with the engine idling when there was a sudden almighty banging. Same thing, crankshaft snapped for no apparent reason.

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300Tdi isn't exactly known for snapping cranks though, so to have similar failures on two engines in rapid succession would be exceptionally bad luck... I'm with Ed, I'd be looking (or at least checking) for some common cause.

What (if any) ancillary parts did you carry over from the old engine when you replaced it? Crank nose pulley? Injection pump? Injectors? Flywheel? They would be my first suspects.

What was the gearbox input shaft like? Is it possible it's bent, or has a failed bearing? With the engine out, does the rest of the drivetrain turn smoothly?

None of this is likely, but neither is snapping two cranks in 1500 miles!

 

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Is the crack on the same cylinder or different one?, imho i think you should have bought a few lottery tickets around the same time. 

I find it hard to comprehend its due to a mechanical item you've installed through a simple engine change... i think its unfortunately just extraordinarily bad luck.

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Well there is some further post-mortem information I neglected to mention so as not to bias initial thoughts.

Crank #1 snapped between No4 and the bearing block between No3 and No4 cylinders. At least one (can't remember if the second one was) of the bolts to the block was sheared. My conclusion on this one was that it was a bolt failure that subsequently caused the crank to snap.

Crank #2 snapped between No 1 and front-most bearing. In hindsight it actually drove all the way down from Oswestry to Pembrokeshire with a Bridgeport in tow with a snapped crank. :rofl:

Drivetrain is in good nick - in summary this vehicle has had in the last 2 years:

  • Rear: Pegged P38 short nose Ashlocker built by Nige with new wheel bearings, Ashcroft halfshafts, drive flanges. New discs, wheels and tyres
  • Front: Pegged Ashlocker built by Nige, new wheel bearings, Ashcroft halfshafts, CVs and drive flanges, wheels and tyres
  • Transfer Box: New sleeved, HD cross pin from Ashcrofts
  • Gearbox: about 8 years ago was replaced because of worn synchros and splines - new R380 from forum member. Input shaft appeared to be in good nick when I swapped engines, there was a slight wiggle in the input shaft but apparently that's not too surprising since it's supported by the end of the crank and this was free floating. Certainly no noises when turning over.
  • Clutch (new Valeo 130 one at time of engine swap)

When I swapped the engine the only things transferred were:

  • Starter motor
  • Alternator
  • Engine mounts
  • Flywheel
  • Cambelt tensioner

It had a new spigot bearing, clutch and cambelt fitted as part of the swap. I'd recently done the cambelt on the original engine, probably about October / November time but it had done about 2000 miles since then. Did the cambelt on the new one as well but the kit supplied despite requesting it didn't have the lipped pulley for the tensioner so reused the (relatively) new one.

So given the drivetrain has been completely overhauled and has been running smoothly for thousands of miles I doubt that.

  • Cambelt / timing - I'd have expected it to not run smoothly rather than snap a crank.
  • Flywheel - possibility but I'd have half expected vibrations or the like if that was enough to break a crank
  • Clutch - original one had done ~100k so unlikely, but was then replaced with a new one (including new release bearings).

One thought I've just had is perhaps the crank pulley wasn't done up tight enough but I did put a large breaker bar and pipe on it the first time around, copious amounts of thread-lock and did it up as tight as I could. The second one when it was out of the vehicle was done up with my Milwaukkee impact (with lots of threadlock) and that's capable of torquing up to 900Nm so it had a good rattle with that.

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So presumably another 300tdi is lined up now for the chop? Like lambs to the slaughter.... Seems very unusual to do one let alone two.

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Is the vehicle your daily driver? Those failures would seriously brass me off.

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25 minutes ago, Happyoldgit said:

Is the vehicle your daily driver? Those failures would seriously brass me off.

Yep - I take these things on the chin. Been lucky I could pinch my Mum's car first when I did the engine swap and then currently pinched Dad's Shogun so I could return a trailer.

37 minutes ago, cackshifter said:

So presumably another 300tdi is lined up now for the chop? Like lambs to the slaughter.... Seems very unusual to do one let alone two.

Nah - at this point if I stay 300Tdi I'll be rebuilding one from the ground up. Turners I see do forged cranks now so that would be my preference. Although I do know of a 6.5L GMC V8 diesel lying around. Not significantly more power (155 in NA form) than a 300Tdi but more than double the torque and being an American engine massively under-stressed.

My friend who's got the engine also built custom bell-housings to adapt them to Land Rover drivetrains so you can leave gearbox and back in the same place and just move engine mounts. The engine doesn't sit further forward so you can leave the viscous fan on and then the only other upgrades are to change the radiator for a Saudi spec one (better cooling for bigger engine) and fit HD springs on the front (which I conveniently have a set lying around) as it's a little heavier. Apparently very easy to use V8 pipes on it as well so everything is off the shelf.

So currently on the lookout for a super cheap (<£500 ideally) runaround, quite fancy a little van actually so I can use that for a few months while I rebuild / fit new engine.

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8 minutes ago, Ed Poore said:

 Although I do know of a 6.5L GMC V8 diesel lying around. Not significantly more power (155 in NA form) than a 300Tdi but more than double the torque and being an American engine massively under-stressed.

Ah so you can snap gearboxes instead of crankshafts! :lol:

Don't those lumps have a terrible reputation as boat anchors?

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3 minutes ago, FridgeFreezer said:

Don't those lumps have a terrible reputation as boat anchors?

I did raise the question since Bob (can always trust a guy named Bob) has plenty of familiarity with them. That reputation apparently largely comes from conversions and they leave the original radiators in. Then you're asking a cooling system that was originally built for a (usually) smaller engine to now cool a 6.5L lump - consequently it overheats and then basically you're always chasing your tail when a diesel has been overheated.

Plus bear in mind this isn't a massive vehicle it's going into and therefore going to be working hard. I mean I'm only asking it to push a brick through the air, not the breeze block that is your ambulance :ph34r:

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35 minutes ago, Ed Poore said:

Nah - at this point if I stay 300Tdi I'll be rebuilding one from the ground up. Turners I see do forged cranks now so that would be my preference. Although I do know of a 6.5L GMC V8 diesel lying around. Not significantly more power (155 in NA form) than a 300Tdi but more than double the torque and being an American engine massively under-stressed.

In a previous discussion on here it was said that probably all 300tdi cranks are forged. I don't know if thats true, but it's perfectly possible of course. One day I'll get bored enough to open my spares engine and have a look.

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I'll take a look at the snapped one I left behind the back door but I'm pretty sure it was cast not forged. It's rusted up a bit while I was away skiing but can quickly knock that off.

 

Benefit of the snapped one is I can actually see the internal structure of the crank.

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57 minutes ago, Ed Poore said:

That reputation apparently largely comes from conversions

I dunno, I'm sure I read a few things on Pirate4x4 many moons ago with a general disdain for them, even in their original application.

I also remember the magazine article way back on the pair of challenge Ibexes running them who were basically counting events-per-gearbox on the fingers of one hand :ph34r:

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I'm currently leaning towards a new crank and rebuild. Possibly since I've got two engines now converting one to a 2.8 but not sure how much of a benefit that gets over just a straight 2.5 with VNT. May get the two cranks out and pop them up to Robin and see what his diagnosis is - find out whether they're cast, if they are then a forged one is a definite improvement.

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I think you need to get the main bearings in-line honed.

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There are some guys in the States fitting Powerstroke 2.8l crate engines into Defenders and Disco 1s. Apparently they suit the application very well.

Just throwing in an option. No idea on ££££ i'm afraid

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43 minutes ago, mickeyw said:

There are some guys in the States fitting Powerstroke 2.8l crate engines into Defenders and Disco 1s. Apparently they suit the application very well.

Just throwing in an option. No idea on ££££ i'm afraid

Many ££££ - at least the Cummins 2.8 re-power that they've done is.

To be honest if I was going down that route I'd be sorely tempted in light of some stuff that may come up in the next few months to get a 3.6TDV8 and ZF 6HP26X running stand-alone :rolleyes:

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3 hours ago, Ed Poore said:

I'm currently leaning towards a new crank and rebuild. Possibly since I've got two engines now converting one to a 2.8 but not sure how much of a benefit that gets over just a straight 2.5 with VNT. May get the two cranks out and pop them up to Robin and see what his diagnosis is - find out whether they're cast, if they are then a forged one is a definite improvement.

As I recall a forged crank was one of the 2.8 TGV improvements; presumably Turners have been buying from Brazil.

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17 hours ago, Ed Poore said:

To be honest if I was going down that route I'd be sorely tempted in light of some stuff that may come up in the next few months to get a 3.6TDV8 and ZF 6HP26X running stand-alone :rolleyes:

Slap an L322 around it and you'll feel right at home !! :)

 

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6 hours ago, V8 Freak said:

Slap an L322 around it and you'll feel right at home !! :)

Nah too fat - don't want to be another @GBMUD in his Freelander. Although to be fair the L322 does have significantly more ground clearance and a better traction control system.

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I am amazed by this run of ill luck.

I can't think of a reason why they'd break.

Are the engine mounts in any way odd? Something must be torquing the blocks? Does the TDI 300 have the ladder frame between the block and the sump?

It must just be bad luck. Amazing.

Sorry to hear of your misfortune.

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Well here's a picture of the first crank. Ignore the rust - it was outside when I went skiing.

DSC_0005.thumb.JPG.9beeef55735e501d0a582390d128be22.JPG

And as of today I might have a plausible explanation. The exterior crank pulley got transferred between engines because (ironically) the "new" one was very rusted up.

I wonder whether I damaged the pulley getting it off after the cambelt change because both engines did a couple of thousand miles after cambelt changes and both then failed. So perhaps the damping bit of the crank pulley was damaged and subsequently cause the harmonics to destroy the crank.

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Sounds like 10 points to TSD then for guessing correctly ;)

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