| [ Total Views: 911 | Total Replies: 8 | Thread Id: 109551 ] |
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 Banshee777
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| posted on July 26th, 2015 at 08:49 PM |
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Spun bearing - is my case still okay?
The PO said the engine spun a bearing and he took the engine apart. I think the centre crank bearing may have spun - can I still use the case or do I
need it machined. Never had to deal with a spun bearing before, any tips welcome.
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Banshee777
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| posted on July 26th, 2015 at 08:55 PM |
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Looking at the case the centre crank bearing is the one I think spun???? I haven't checked the rods or anything for damage yet, getting dark in the
garden shed.
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psimitar
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| posted on July 26th, 2015 at 09:15 PM |
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Yea the No.2 saddle has rotational wear markings there.
Normally a spun bearing means machining but if the case measures within OE tolerances and you're on a budget then you may get away with it.
Thing is, why did it spin the bearing? Loose dowel pin, no dowel pin, worn case leading to loose bearing fit, bent crank, out of align case crank
saddles?
Just for piece of mind I'd first see if the case is warped, done using an engineers straight edge across the length of the case over the 4 crank
saddles. If a 0.02mm feeler gauge can get under the straight edge then case mating faces need machining level and then both crank and cam need align
boring. Most just scrap the case due to the machining work required.
If the case isn't warped then have it align bored and check the bearing dowels are a snug fit in their holes and the new bearings 
Maybe whilst the case is apart get it clearanced for an 82mm crank 
madness is in the eye of the beholder  |
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ragged
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| posted on July 27th, 2015 at 12:37 AM |
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When a main bearing locks up on the crankshaft, it will spin in the case. When that happens, the locating dowel hole gets destroyed. I can not see any
evidence of a spun main bearing in the photos, but then again the only main bearing I have ever seen spin is the number 1, next to the flywheel, but
you do not have a photo of that journal.
There is not much that can be diagnosed in a photograph, other than damage, but I can see by the 'shine' the centre main bearing has been moving in
the case and will need to be properly measured to determine whether the case requires facing and tunnel boring.
Also, check the condition of the cylinder sealing surfaces too.
Dave
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Banshee777
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| posted on July 27th, 2015 at 07:00 AM |
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Thanks guys, appreciate the feedback. I think I'll try for a better condition case to base a rebuild on.
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 Bizarre
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| posted on July 27th, 2015 at 08:47 PM |
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| Quote: | Originally
posted by Banshee777
. I think I'll try for a better condition case to base a rebuild on.
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I would get it checked first
It "could" be an untouched case that would be on its first line bore - and nothing wrong with that
I would take a well seasoned original dual relief case that had only 1 cut before a suspect new case anyday
Futue te ipsum!!!
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ragged
A.k.a.: David
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| posted on July 27th, 2015 at 09:48 PM |
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Yes, agree with Bizarre. There is nothing in those photos that suggest the case is not good to re use. It needs to be measured up before you toss it
and find another.
You can't always go by what the PO says. It may have spun a bearing, but most likely a big end, not the main bearing. If you have the crankshaft that
came out of the case it would be easy to determine.
Dave
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vlad01
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| posted on July 28th, 2015 at 07:37 PM |
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nah, not spun. just fretting marks.
When a bearing spins, you'll know about it, especially a main bearing. The main bore would be absolutely trashed in minutes of it happening, shredded
like an asshole wiped with a cheese grater.
71 notchback,
Past owner of, 70 NB, 73 SB and 72 FB TLE |
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Banshee777
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| posted on July 29th, 2015 at 12:00 PM |
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Cheese grater......
So I've decided to learn about putting a VW engine together by.....putting one together and this is a good opportunity with a stack of unknown parts.
If I can get a running engine and learn something along the way then great and I'll be happier to then spend my money on the new parts (maybe a new
case) and building a stroker to keep.
Inspiration is from this post on another forum:
http://www.thesamba.com/vw/forum/viewtopic.php?t=533158
And I'll use this post as the basis for the build itself (plus I have 2 VW engine books on the way).
http://www.thesamba.com/vw/forum/viewtopic.php?t=513083
I'll include some photos so you can all cringe at the spectacle, should be some fun  
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