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Discussion Starter · #1 ·
Hey guys,
This is Mike Tracy's son Jon. I was taking apart in the hopes to rebuild a 70 opel engine. While doing this I pulled out the pistons to find that number 1 piston and the crank shaft were damaged. I was wondering if it would still be ok to put those back in the engine?
 

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Über Genius
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9,375 Posts
Would a surgeon put in a damaged heart?

You don't put damaged parts in your car unless you don't care about it
 

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Old Opeler
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5,564 Posts
Nasty!

Jon,

Something nasty is happening there: The piston skirt is actually impacting on the crankshaft's counterweight. That piston itself is probably cracked from the thrashing and the conrod it is attached to may well be bent due to the one-sided impacts. The other three pistons should be carefully checked also to see if they have similar impact marks. The rod journals and bearings will have been affected too.

The piston must not be an Opel one as the clearance is all wrong on the skirt????
 

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Opeler
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107 Posts
What I think happened is a object got dropped into the and got caught between the crank and the piston. This motor has been "rebuilt" at least three times. (at least two of those times by poeple who had no idea as to what they were doing, one being me). So we have no clue as to what's stock and what's not. The damage to the crank, fixable? We have two other cranks but they both need to be cleaned up. What do costs normally run to have cranks turned?
 

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Senior Contributor
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It's not much to have a crank turned (or fluxed for hidden nasties). Around here, it's about $80 to $120 for turning and $8.50 a cyl for boring. I agree with
First Opel.It's much easier, cheaper and in the end, less fustrating, to fix things before re-assy. Things have a habit going together much better.
Just my 2c's :rolleyes:
 

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Über Genius
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9,375 Posts
The crank looks like it would be OK. Check it to make sure the journals are OK. If the mark is a scrape, it won't hurt anything. Just clean it up. If it is a gouge like something got caught when the engine was running, I would rely on a different crank. Or you can have it checked for true.

Either way, don't put it back in unless you know its good. You wouldn't want it screwing up your block.

And I would never use that piston again
 

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If it were me I would find another use for that piston, not car related. They do make for a real nice ash tray, I have a really high priced Arias ash tray here or a really small boat anchor. As far as the crank is concerned I'd get a set of oversize bearings and have the crank ground to match them. That is a very important piece to any motor and if you want it to last at all it deserves to be as close to perfect as you can get.JM2CW
 

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Old Opeler
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Stress

On further reflection: "Would you pound on the crankshaft or piston with a hammer before you put it back into your motor?"

1) If you are in a - just get it going - situation then replace the rod and piston with items of the same (or very similar) weights. Also check that the crank turns freely in the block in case it has been bent by the abuse.

2) If your are rebuilding the motor - get another one that has not been treated quite like the one you have.

The rod bolts will have been given a fatal workout too.
 

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Opeler
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OK, good advise, We will check around to see what is would cost to have the crank done. Piston is cracked and I will have to see what we have for rods. We (I should say Jon is) just hopeing to get a running car out of this as we have no budget for it. If any of you have a set of pistons and rods that are good and usable (not looking for anything fancy) or know of a inexpensive source, let us know. We do want to do this right but budget is the driving force. Jon has a year before he will be driving and He is hopeing to have it running by then.
 
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