Crankshaft--can it be reused?

[Klaus Schlueter]

Hi all experts,

recently I have asked where I can buy a crankshaft an I received some good tips from kryten and flying farmer. I have digged out my spare crankshaft and found that it doesn't look too bad. The wear on all journals except one is minimal or zero--just the shiny parts and the grey track of the oil groove. The diameter is 44,19 mm i.e. once reground.
On one big end journal for the pistons in cylinder no. 7 and 8 I can feel a slight step with the fingernail/fingertip and detect very fine groove marks. At the step I measure a wear of 0,02-0,03 mm. This wear is only on one side of the double journal (on the center side of the crankshaft), that means the journal is 0,02-0,03 mm oval.
I have tried to make some pictures but it is difficult to show the effect. 1 and 2 are the critical journal, 3 shows a better one.

My questions: would you dare to use this crankshaft again w/o redoing it? Has anybody made experience (good or bad) with such an attempt?

I will survive if I spend the GBP 240 but it is tempting....

Any opinions are very welcome.

Regards Klaus

DSC03727.jpgDSC03729.jpgDSC03730.jpg

[milothedog]

Hi all experts,

recently I have asked where I can buy a crankshaft an I received some good tips from kryten and flying farmer. I have digged out my spare crankshaft and found that it doesn't look too bad. The wear on all journals except one is minimal or zero--just the shiny parts and the grey track of the oil groove. The diameter is 44,19 mm i.e. once reground.
On one big end journal for the pistons in cylinder no. 7 and 8 I can feel a slight step with the fingernail/fingertip and detect very fine groove marks. At the step I measure a wear of 0,02-0,03 mm. This wear is only on one side of the double journal (on the center side of the crankshaft), that means the journal is 0,02-0,03 mm oval.
I have tried to make some pictures but it is difficult to show the effect. 1 and 2 are the critical journal, 3 shows a better one.

My questions: would you dare to use this crankshaft again w/o redoing it? Has anybody made experience (good or bad) with such an attempt?

I will survive if I spend the GBP 240 but it is tempting....

Any opinions are very welcome.

Regards Klaus

[ATTACH=CONFIG]20103[/ATTACH][ATTACH=CONFIG]20104[/ATTACH][ATTACH=CONFIG]20105[/ATTACH]

According to the ROM Klaus that's just under the limit (0.05mm) for ovality and taper so a bit too close I think, why not have it machined, it will still only be +20 if I understand correctly and a second grind will be much cheaper I would have thought.

Ian.

[Klaus Schlueter]

Ian, do you mean machine just the one journal w/o hardening?

Klaus

[milothedog]

Ian, do you mean machine just the one journal w/o hardening?

Klaus

No Klaus,

have the Crank re machined with the minimum removed (another 10 thou) and if it is original have it hardened.

Ian.

[Staggard]

I agree with Ian it's worth it just peace of mind, removeing, rebuilding, and replaceing and engine is a lot of work and expence not something you want to do twice. Graham

[joel h]

No Klaus,

have the Crank re machined with the minimum removed (another 10 thou) and if it is original have it hardened.

Ian.

Hi Ian, you say if its original have it hardened. why only if its original?
cheers
Joel.

[milothedog]

Hi Ian, you say if its original have it hardened. why only if its original?
cheers
Joel.

If it's an original crank then in all likelihood it wouldn't have been hardened so it would be wise with the methods now available to give it some longevity

Ian.

[joel h]

o.k thanks Ian.
Joel.

[GDPR]

The original wouldn't have been hardened due to the trimetal bearing shells at the time, which were faced with lead indium and other forgiving alloys which gave the crank an easy time until the oil pressure was up.

Modern shells are faced with aluminium, which will win a fight with the journal surface, so hardening is carried out so that the journal is more resistant - simples

Klaus - that crankshaft journal is past its sell by date, I certainly wouldn't reuse it until it had been ground, hardened and polished - all of them

Russ

[Ian Durrant]

The original wouldn't have been hardened due to the trimetal bearing shells at the time, which were faced with lead indium and other forgiving alloys which gave the crank an easy time until the oil pressure was up.

Modern shells are faced with aluminium, which will win a fight with the journal surface, so hardening is carried out so that the journal is more resistant - simples

Klaus - that crankshaft journal is past its sell by date, I certainly wouldn't reuse it until it had been ground, hardened and polished.

Russ

You are right Russ that aluminium bearings almost certainly don't help but Stag cranks needed hardening after grinding even when lead indium bearings were the norm. I guess its the small mains bearing surface area that's the main culprit as the cranks are good steel (EN 24?) if my memory serves me correctly.

[flying farmer]

The biggest problem with a worn crank is knowing wether it was hardened or not. If it was it may have taken a lot of miles to get that worn and might do a lot more before it gets too bad.

However, speaking from experience, the crank on the last engine I stripped after its jackshaft seizure had significant wear after only about 30'000 miles (judging from the reciepts that came with the car).

I suspect the crank was not hardened after regrinding, and the crank wear was double the bearing shell wear (aluminium bearings)

A couple of pictures among this lot...http://s740.photobucket.com/albums/x...3DDSCF0088.jpg

[Klaus Schlueter]

Many thanks to all who have replied. Your message is absolutely clear and I will follow your advice.

Regards Klaus