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oh crap
- Thread starter grolls
- Start date
grolls
Well-Known Forum User
ben240z
Club Member
how would xraying the block pick up a crack in the crank.
ben240z
Club Member
without teaching you to suck eggs when you rebuild this engine make sure you have a good look at the rear main cap. When you put the crank back in it will be tight on number 6 journal due to some damage to the rear bearing housing. A small amount of work on the rear face of the no 6 main bearings will allow the crank to rotate freely.
Grolls
Looking at the pictures of your crankshaft, looks like a fatigue fracture. The 'smoother' surface to the right of the red line being the fatigue fracture, the rougher surface to the left clatter from the final break. Usually fatigue fractures start from a stress raiser (sharp corner/notch).
Fatigue failure occurs in three stages – crack initiation; slow, stable crack growth; and rapid fracture. The growth of the dominate crack or cracks will continue until the remaining un-cracked section of the component can no longer support the load. At this point, the fracture toughness is exceeded and the remaining cross-section of the material experiences rapid fracture.
Worryingly the fatigue fracture looks as if it started from what I assume is the oil way, not easy to tell from the photograph. If you want to know the exact cause and starting place, I can get a metallurgist to look at the fracture for you (FOC).
When using ‘second hand’ crankshafts it is best to get them ‘crack tested’ before re-building the engine using the magnetic particle test method.
Regards
Ian
Looking at the pictures of your crankshaft, looks like a fatigue fracture. The 'smoother' surface to the right of the red line being the fatigue fracture, the rougher surface to the left clatter from the final break. Usually fatigue fractures start from a stress raiser (sharp corner/notch).
Fatigue failure occurs in three stages – crack initiation; slow, stable crack growth; and rapid fracture. The growth of the dominate crack or cracks will continue until the remaining un-cracked section of the component can no longer support the load. At this point, the fracture toughness is exceeded and the remaining cross-section of the material experiences rapid fracture.
Worryingly the fatigue fracture looks as if it started from what I assume is the oil way, not easy to tell from the photograph. If you want to know the exact cause and starting place, I can get a metallurgist to look at the fracture for you (FOC).
When using ‘second hand’ crankshafts it is best to get them ‘crack tested’ before re-building the engine using the magnetic particle test method.
Regards
Ian
grolls
Well-Known Forum User
A fair point.....one I do need to check before assembly etc....but thanks for the reminder.
grolls
Well-Known Forum User
Yes it does look like it stemmed from the oil way, thanks for the offer, but the cranks a gonner...so just looking ahead now....
Interesting info. Decay.
SeanDezart
Well-Known Forum User
Less than you did.......by a lot...
Yep and mine's still running after 4 years and countless track-days and several thousand miles of spirited driving
!Ben - no, not directly but having the block tested thoroughly is primordial and would have shown up any problems in the oil ways and also water ways. That's what also bumps up the price of built-to-order engines.
I've spent a considerable amount of money having a performance engine (essentially a road engine) that is reliable because :
a) I don't want the time lost and car off the road/breakdowns
b) I don't want the expense of having it stripped down every 'x' miles
c) I'm crap at that and lazy
I assume that the crank was balanced ?
grolls
Well-Known Forum User
Yep and mine's still running after 4 years and countless track-days and several thousand miles of spirited driving
Ben - no, not directly but having the block tested thoroughly is primordial and would have shown up any problems in the oil ways and also water ways. That's what also bumps up the price of built-to-order engines.
I've spent a considerable amount of money having a performance engine (essentially a road engine) that is reliable because :
a) I don't want the time lost and car off the road/breakdowns
b) I don't want the expense of having it stripped down every 'x' miles
c) I'm crap at that and lazy
I assume that the crank was balanced ?
Sean,
I think if you re-read Bens post he is asking how x raying the block will stop the crank from breaking.....and rightly so.
As for my engine, yes it was checked and double checked and all was well so no need to do anymore. Yes the crank was balanced.
I cant help it if a 32 year old crank finally gave up the ghost.....I think it did well personally.
Stick to brylcream n tarmac.........:lol:
SeanDezart
Well-Known Forum User
Grolls - I read well what Ben said - obviously it wouldn't have prevented any issues directly from the crank. But it would have prevented any secondary isses leading to other component damage. You say checked and re-checked....how ? And are you going to have it x-rayed now ?
All I remember is that at Le Mans you revved the nuts off it outside the camping and to do that safely, an engine must be prepared properly - THAT, done frequently can also accelerate wear and fatigue.
If, after all that you still consider that everything was ok - you are the unluckiest zedder here mate.
grolls
Well-Known Forum User
Grolls - I read well what Ben said - obviously it wouldn't have prevented any issues directly from the crank. But it would have prevented any secondary isses leading to other component damage. You say checked and re-checked....how ? And are you going to have it x-rayed now ?
All I remember is that at Le Mans you revved the nuts off it outside the camping and to do that safely, an engine must be prepared properly - THAT, done frequently can also accelerate wear and fatigue.
If, after all that you still consider that everything was ok - you are the unluckiest zedder here mate.
Well to answer those, purchased a "spike engine" as best that could be established. Sat for may years well oiled up before i bought it. Stripped and checked all bearings, free play, end float, n made note of scribe marks where crank etc was ballanced. Re-oiled all bearings, checked cam, valves, etc all seemed spot on. As for re xray new crank....nope not going to bother.....if it breaks so be it....rb or v8/v12 are in the line of thoughts.
Yes to balanced now.......new cam kit.....ta Mr F and a few other bits from others that should take it nearer the 250 marque......
SeanDezart
Well-Known Forum User
Are those Rebello horses ?:lol:Yes to balanced now.......new cam kit.....ta Mr F and a few other bits from others that should take it nearer the 250 marque......
grolls
Well-Known Forum User
Soz, i forgot to add this, I never, ever rev the nuts of it, High revving never until warm and only to the orange max as no need to hit the red line as no need too, but even you commented how "tight every thing felt" THATS BECAUSE im a stickler for what it right and one that has nowt to prove......lol
SeanDezart
Well-Known Forum User
Well, you never let me drive her - it was you that felt tight darling but they do say that rounder people make for tighter h*les. The engine felt linear, as if you had to rev her to squeeze the power out - do you know what cam was in ?
grolls
Well-Known Forum User
ben240z
Club Member
hahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahaahahahahahahahahahahahahahahaahahha
ever the economist in the word department.
Sean said:
I have some interesting info on that matter, after considerable research we have found out that Americans actually use a power unit based on a "pony" (power) rather than our traditional "horse" (power)
1 HP or Horse power is equivalent to 746 watts and the US version is 492 watts
This all stems to when the American pony was the common mode of transport (pony express) where as in Britain the "horse" was a much larger animal and as a consequence was able to pull a larger load
The Pony is only around 2/3rd the size of a Horse (plough horse) and as a result the pony measure is ony around 2/3rds of a horse (power) so 100 bhp US stylee is actual only around 66 bhp
The research did infer a link to the Mustang (see best selling car named after horse) in respect of being slightly better than a pony but more tempremental and less reliable
This should help clear up any misunderstandings on the apparent high hp claims coming from the US
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