Broken Crank Shaft
Discussion
Oh no !!!!!! 
My 1996 4.2L AJP has just suffered from a broken Crank shaft. What now?????
I can see Powerperformance have 22weeks lead time. Is there anywhere else I can get a new (or 2nd hand) one?
Is it simple to change it (has anyone made a guide how to)? I was warned that since my engine is old then a new crank shaft may not fit without modification of the engine. Can any one confirm if that is true?
Alternatively, I could change the engine, preferable with a 4.5L. Do any of you know were I can find another engine?
Sad regards
My 1996 4.2L AJP has just suffered from a broken Crank shaft. What now?????
I can see Powerperformance have 22weeks lead time. Is there anywhere else I can get a new (or 2nd hand) one?
Is it simple to change it (has anyone made a guide how to)? I was warned that since my engine is old then a new crank shaft may not fit without modification of the engine. Can any one confirm if that is true?
Alternatively, I could change the engine, preferable with a 4.5L. Do any of you know were I can find another engine?
Sad regards
Thomas, its engine rebuild time I'm afraid.The engine needs to come out and the sump removed to remove the broken crankshaft. I'd bet any engine builder would want to strip it completely to ensure any small bits of the crankshaft are removed so they dont cause damage later. Later engines use a crankshaft with 2.5" diameter main bearings, whereas your engine has an early crankshaft with 2.3" diameter journals. Whats interesting is that it's very rare (unheard of even?) for the later crankshafts to snap, but the early type never snapped at the journals. When it comes to putting the engine back together you could use a small journal crankshaft if you could find one but it might snap again, or you line bore the block and fit a later crankshaft. I do have an early crankshaft removed from my engine when it was rebuilt but its sat rusting for a couple of years now. It may be beyond usable, I don't know. I upgraded to the later crankshaft because I could afford a new crank a lot more than I could afford a 2nd engine rebuild!
CerbWill said:
Thomas, its engine rebuild time I'm afraid.The engine needs to come out and the sump removed to remove the broken crankshaft. I'd bet any engine builder would want to strip it completely to ensure any small bits of the crankshaft are removed so they dont cause damage later. Later engines use a crankshaft with 2.5" diameter main bearings, whereas your engine has an early crankshaft with 2.3" diameter journals. Whats interesting is that it's very rare (unheard of even?) for the later crankshafts to snap, but the early type never snapped at the journals. When it comes to putting the engine back together you could use a small journal crankshaft if you could find one but it might snap again, or you line bore the block and fit a later crankshaft. I do have an early crankshaft removed from my engine when it was rebuilt but its sat rusting for a couple of years now. It may be beyond usable, I don't know. I upgraded to the later crankshaft because I could afford a new crank a lot more than I could afford a 2nd engine rebuild!
Most, maybe all of the reputable engine builders won't offer a warranty on a small journal crank.Line boring is the way to go and a large journal crank.
While you are at it you may as well put 4.5 liners and pistons or go for 4.7 in it and have a fully refreshed engine.
A few people on here have done this when faced with your current situation.
darreni said:
Mine went in 2003 & i had the car shipped back to the factory. They fitted a 4.5 crank & a load of engine work. It was with them for a month & the parts cost was just shy of 10k.
Yes, the though has come to me but the price is +10K and for the price I might be able to find "new" engine and the use the old for spares.How did yours?
CerbWill said:
Thomas, its engine rebuild time I'm afraid.The engine needs to come out and the sump removed to remove the broken crankshaft. I'd bet any engine builder would want to strip it completely to ensure any small bits of the crankshaft are removed so they dont cause damage later. Later engines use a crankshaft with 2.5" diameter main bearings, whereas your engine has an early crankshaft with 2.3" diameter journals. Whats interesting is that it's very rare (unheard of even?) for the later crankshafts to snap, but the early type never snapped at the journals. When it comes to putting the engine back together you could use a small journal crankshaft if you could find one but it might snap again, or you line bore the block and fit a later crankshaft. I do have an early crankshaft removed from my engine when it was rebuilt but its sat rusting for a couple of years now. It may be beyond usable, I don't know. I upgraded to the later crankshaft because I could afford a new crank a lot more than I could afford a 2nd engine rebuild!
Why did you get the engine rebuild if the crankshaft was intact? Do you have any photos of the small journals crankshaft you have and is it up for adoption ? 
As it is a '96 I suspect you had one of the early small journal cranks, which are a ticking time bomb by all accounts. Especially with TVR tolerances on balancing..
There was a later small journal crank which as far as I am aware, doesn't tend to break unless you get a bad casting..
There was also a billet small journal, then the later cast large journal.
Could be worth seeing if anyone would make you a billet small journal crank using your current one as a basis. Save you having to line bore.
The small/large journal has nothing to do with strength, TVR changed over when Rover did as it runs RV8 bearings. It was just the earlier small journal crank which either had not enough counterweight, or poor castings.
There was a later small journal crank which as far as I am aware, doesn't tend to break unless you get a bad casting..
There was also a billet small journal, then the later cast large journal.
Could be worth seeing if anyone would make you a billet small journal crank using your current one as a basis. Save you having to line bore.
The small/large journal has nothing to do with strength, TVR changed over when Rover did as it runs RV8 bearings. It was just the earlier small journal crank which either had not enough counterweight, or poor castings.
Jhonno said:
As it is a '96 I suspect you had one of the early small journal cranks, which are a ticking time bomb by all accounts. Especially with TVR tolerances on balancing..
There was a later small journal crank which as far as I am aware, doesn't tend to break unless you get a bad casting..
There was also a billet small journal, then the later cast large journal.
Could be worth seeing if anyone would make you a billet small journal crank using your current one as a basis. Save you having to line bore.
The small/large journal has nothing to do with strength, TVR changed over when Rover did as it runs RV8 bearings. It was just the earlier small journal crank which either had not enough counterweight, or poor castings.
As you point out the problem is finding a crankshaft. Has anyone any suggestion where I can get one? I live abroad, which make things even more complicated when owning a TVR There was a later small journal crank which as far as I am aware, doesn't tend to break unless you get a bad casting..
There was also a billet small journal, then the later cast large journal.
Could be worth seeing if anyone would make you a billet small journal crank using your current one as a basis. Save you having to line bore.
The small/large journal has nothing to do with strength, TVR changed over when Rover did as it runs RV8 bearings. It was just the earlier small journal crank which either had not enough counterweight, or poor castings.
I have looked around, but none of the local workshops are capable of making a new crankshaft based on the old. Do you know of any specialist in UK who would be able to do so? Jhonno said:
As it is a '96 I suspect you had one of the early small journal cranks, which are a ticking time bomb by all accounts. Especially with TVR tolerances on balancing..
Do you know what the tolerances should be, if I can find someone to make a new crankshaft based on the old one?thomas.moeller said:
Why did you get the engine rebuild if the crankshaft was intact? Do you have any photos of the small journals crankshaft you have and is it up for adoption ?
Inlet valves weren't sealing properly. It started as a head refurb. I then decided to have the crank replaced as I could afford a crank a lot more than a 2nd rebuild if it snapped. As I was spending a fair bit of money at that point it seemed a shame that I wouldnt get any more power out of it, so I went all in and went for the 4.7 upgrade.I'll send some photos of the crank over later. It came out of my engine having done roughly 83k miles. I've no idea whether it will go on forever or if it'd snap at the first start of a new engine. I would really only advise it if you're desperate, on a tight budget, and can either rebuild the engine yourself or have someone with the necessary skills and experience who is willing to do it for you with the known risks around the early cranks.
gruffalo said:
Most, maybe all of the reputable engine builders won't offer a warranty on a small journal crank.
Line boring is the way to go and a large journal crank.
While you are at it you may as well put 4.5 liners and pistons or go for 4.7 in it and have a fully refreshed engine.
A few people on here have done this when faced with your current situation.
I'm sure I've seen a post along those lines from Byker28i. Cant remember who built his engine but it was one of the reputable specialists.Line boring is the way to go and a large journal crank.
While you are at it you may as well put 4.5 liners and pistons or go for 4.7 in it and have a fully refreshed engine.
A few people on here have done this when faced with your current situation.
Speculating that Thomas' intent is a quick fix to get a summer's motoring in I think 'patching it up' with a small journal crank is risky and will take a significant amount of time to achieve. Given his location listed location is Denmark unless he's very handy with the spanners and has some engine building experience it might be time to consider crating the engine up and sending it to Powers Performance or APM.
Thomas, who has diagnosed a snapped crank, what state is the engine in now? It could (but hopefully hasnt) damaged the block so just putting another crank in may not even be possible. You won't know until the engine is in bits, unless there's a rod through the block!
CerbWill said:
Speculating that Thomas' intent is a quick fix to get a summer's motoring in I think 'patching it up' with a small journal crank is risky and will take a significant amount of time to achieve.
If your crank has made it to 83k, it is likely to be the safer later small journal crank, and probably is a good casting. Of course no guarantees, but cranks that are going to snap seem to do it before 40k..CerbWill said:
Speculating that Thomas' intent is a quick fix to get a summer's motoring in I think 'patching it up' with a small journal crank is risky and will take a significant amount of time to achieve. Given his location listed location is Denmark unless he's very handy with the spanners and has some engine building experience it might be time to consider crating the engine up and sending it to Powers Performance or APM.
Great advice from WillIf you want to use the car this summer you will need to find a replacement engine, and the usual suspects do advertise 4.2 engines sometimes
https://www.ebay.co.uk/itm/324023195844
It is probably fair to say that would be a gamble, with a very big ante - probably at least £5k for the engine, and another £1k to ship/swap/recommission as a base cost
Having your own engine rebuilt would probably cost something similar, take a lot longer, but be a better bet in the long run
You might be able to halve costs as a DIY job, but being realistic you should assume it will take you a year, unless you're not working
This one didn't do any damage to the block or heads - Thankfully not my car
Edited by ukkid35 on Wednesday 9th June 12:10
CerbWill said:
As I was spending a fair bit of money at that point it seemed a shame that I wouldnt get any more power out of it, so I went all in and went for the 4.7 upgrade.
How much power did you gain from this conversion? Did you also get a new ECU or is it running on the factory fitted one? How much did you spend on this upgrade?
CerbWill said:
Speculating that Thomas' intent is a quick fix to get a summer's motoring in I think 'patching it up' with a small journal crank is risky and will take a significant amount of time to achieve. Given his location listed location is Denmark unless he's very handy with the spanners and has some engine building experience it might be time to consider crating the engine up and sending it to Powers Performance or APM.
Thomas, who has diagnosed a snapped crank, what state is the engine in now? It could (but hopefully hasnt) damaged the block so just putting another crank in may not even be possible. You won't know until the engine is in bits, unless there's a rod through the block!
Thomas, who has diagnosed a snapped crank, what state is the engine in now? It could (but hopefully hasnt) damaged the block so just putting another crank in may not even be possible. You won't know until the engine is in bits, unless there's a rod through the block!
The car has been diagnosed by my local garage. It has not been totally dismantled so there is the risk that the block is damaged. A least we have not seen any signs of this.
Is the exhaust, the engine harness and the ECU the same for the 4.5 and 4.7 ? (ie. can I just box up the engine, get it rebuild and then fit it back in without doing any other modifications?)
Edited by thomas.moeller on Wednesday 9th June 13:49
ukkid35 said:
If you want to use the car this summer you will need to find a replacement engine, and the usual suspects do advertise 4.2 engines sometimes
https://www.ebay.co.uk/itm/324023195844
It is probably fair to say that would be a gamble, with a very big ante - probably at least £5k for the engine, and another £1k to ship/swap/recommission as a base cost
This is also an early 4.2.. For parts/rebuild only imo. https://www.ebay.co.uk/itm/324023195844
It is probably fair to say that would be a gamble, with a very big ante - probably at least £5k for the engine, and another £1k to ship/swap/recommission as a base cost
thomas.moeller said:
CerbWill said:
As I was spending a fair bit of money at that point it seemed a shame that I wouldnt get any more power out of it, so I went all in and went for the 4.7 upgrade.
How much power did you gain from this conversion? Did you also get a new ECU or is it running on the factory fitted one? How much did you spend on this upgrade?
CerbWill said:
Speculating that Thomas' intent is a quick fix to get a summer's motoring in I think 'patching it up' with a small journal crank is risky and will take a significant amount of time to achieve. Given his location listed location is Denmark unless he's very handy with the spanners and has some engine building experience it might be time to consider crating the engine up and sending it to Powers Performance or APM.
Thomas, who has diagnosed a snapped crank, what state is the engine in now? It could (but hopefully hasnt) damaged the block so just putting another crank in may not even be possible. You won't know until the engine is in bits, unless there's a rod through the block!
Thomas, who has diagnosed a snapped crank, what state is the engine in now? It could (but hopefully hasnt) damaged the block so just putting another crank in may not even be possible. You won't know until the engine is in bits, unless there's a rod through the block!
The car has been diagnosed by my local garage. It has not been totally dismantled so there is the risk that it the block is damaged. A least we have not seen any signs of this.
Is the exhaust, the engine harness and the ECU the same for the 4.5 and 4.7 ? (ie. can I just box up the engine, get it rebuild and then fit it back in without doing any other modifications?)
Mine came off the rollers there with 435 BHP at the wheels, the guessing is on this being around 475+ at the flywheel and 410lbft of torque, the torque curve is almost flat from 3000rpm to 7000rpm.
The engine is a dream to drive, still completely mental but now less dependent on revs in order to deliver its push, the torque is infectious, I have the beating of mates Telsa Model 3 Performance track set up car every where from 20 to 120 and above 90 I leave him for dust, quite level to 90mph, with the Cerbera slightly in the lead.
Byker28i on here had his engine shipped to STR8SIX re built and shipped back, there are standard maps available for the 4.7 but you get the best out of it by getting it mapped, Jools (Kits and Classics) or powers can do this for you but they will require the car and for it to have been run in first.
The loom is the same as is everything else but you will need bigger injectors which would come with the engine.
Thomas - as said - mine engine was removed and replaced by someone else who had storage for the car, whilst STR8Six rebuilt the engine. Jason did a brilliant job.
Mine was an early 97 engine with the small bearing crank, which had done around 55K miles and was running fine, I was just starting to get lower compression on some cylinders due to worn valve guides. The early heads were brass valve guides with different (chrome?) valves.
So heads were reworked to modern standard, new valves, guides, block was ok and the bore wasn't worn but it was crosshoned and new rings fitted.
Str8six wouldn't warranty the engine without replacing the crank for the later large journal one - so that was £1750 for the crank and all machining was another £600. The full engine refresh and rebuild to latest standards, but still 4.2 was £13k with VAT added.
I think in the thread about my engine I listed the bill...
Mine was an early 97 engine with the small bearing crank, which had done around 55K miles and was running fine, I was just starting to get lower compression on some cylinders due to worn valve guides. The early heads were brass valve guides with different (chrome?) valves.
So heads were reworked to modern standard, new valves, guides, block was ok and the bore wasn't worn but it was crosshoned and new rings fitted.
Str8six wouldn't warranty the engine without replacing the crank for the later large journal one - so that was £1750 for the crank and all machining was another £600. The full engine refresh and rebuild to latest standards, but still 4.2 was £13k with VAT added.
I think in the thread about my engine I listed the bill...
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