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| How do I know a crank is any good? http://www.international2cvfriends.com/forum/viewtopic.php?f=7&t=4272 |
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| Author: | Russell [ October 9th, 2012, 9:11 pm ] |
| Post subject: | How do I know a crank is any good? |
So, I've started stripping an engine down as it was a bit of an unknown and wouldn't start when I bought the scrap car it came from. I want it to last quite a while and be as quick as my pocket/talent allow. I've got it down to the two crank cases with the crank, cam and oil pump etc still on/in it. The oil was thick and very black, the pistons appeared to have black sludge on them and the tappet chests are all jet black, instead of the usual alloy colour under the oil. The pistons have huge score marks on them and I would consider them to be cattle-trucked. I've never split crank case halves before, but before I do so, is there an obvious and easy way for me to tell if this crank is scrap? I've no real reason to suspect it is other than its not had oil changes as regularly as it perhaps should, and even if I don't suspect it's duff I don't know any history of it nor have I heard it run and I don't want to build the engine up around it if I've got to chuck it away and start again upon the first startup of it. |
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| Author: | lpgo [ October 9th, 2012, 9:44 pm ] |
| Post subject: | Re: How do I know a crank is any good? |
surfaces where the bearings run need to be shiny and without marks. Then hold it by a connecting rod with the hole where the piston is attached up, let the rest hanging down. now when you hammer at the top (with a big plastic hammer) of the connecting rod you can feel it it has any play, if not then it's good, then do the same with the other connecting rod... hope you understand again my english is crap sorry... |
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| Author: | Sean [ October 9th, 2012, 10:12 pm ] |
| Post subject: | Re: How do I know a crank is any good? |
As Lpgo says but give it a swill in petrol/brake cleaner etc as i was given one of these engines once as it had a good crank and "they are the best ones" all felt smooth and tight but once the rancid semi set oil and varnish was removed there was nearly 1mm end float on the con rods  As you leave the assembly hanging from you left hand and give the top of the little end a smack with your right you can hear the "clack" on a gubbed one (Ken showed me that) |
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| Author: | lpgo [ October 9th, 2012, 10:19 pm ] |
| Post subject: | Re: How do I know a crank is any good? |
@ Sean Thanks for translating 
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| Author: | Russell [ October 9th, 2012, 10:41 pm ] |
| Post subject: | Re: How do I know a crank is any good? |
I think I understand, I hold it by the gudgeon pin hole with the rest of the assembly hanging down, and I hit it with a plastic dead blow hammer and I'll feel if there's any play in it. Where exactly do I hit it and in which direction? On the rod I'm holding and in the direction it travels when it's rotating? |
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| Author: | lpgo [ October 9th, 2012, 10:48 pm ] |
| Post subject: | Re: How do I know a crank is any good? |
See it like a (dead) chicken, take the chicken by 1 leg, body hanging down , now hammer from above on the foot, you feel/hear when crank has play in connectingrod ...... 
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| Author: | lpgo [ October 9th, 2012, 10:56 pm ] |
| Post subject: | Re: How do I know a crank is any good? |
Attachment: dead chicken.jpg |
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| Author: | ken [ October 9th, 2012, 11:35 pm ] |
| Post subject: | Re: How do I know a crank is any good? |
Ipgo, I find that you don't need to use a hammer, just wear gloves and hit the top of the conrod that's held in one hand with the heel of your other hand. If there's a 'clack' sound, that means there's wear in the big end of the conrod you're holding... @ Russell, sounds as though there's been some serious neglect with oil changes, so be sure to have a close look at the camshaft lobes, the cam followers and also the tips of the rockers where they contact the valves. ken |
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| Author: | Russell [ October 9th, 2012, 11:39 pm ] |
| Post subject: | Re: How do I know a crank is any good? |
Thanks all of you. Dead chicken analogy worked fine. I wonder if you hit a chicken like that what sound it makes? |
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| Author: | ayjay [ October 10th, 2012, 12:27 am ] |
| Post subject: | Re: How do I know a crank is any good? |
with a chicken, you pull up on the neck! my brother has a 2cv that hes building, the engine is complete i rocked the flywheel to&fro at different points to check if there was any play in the big end/s its all good --------------- sorry about my grammer, apparently its crap on tother site heres some commas ,,,,,,,,,,,,,,,,,,, |
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