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Spun bearing - is my case still okay?

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Banshee777 Commited Dubber

74 posts · joined Jun 2015 ·

#1017067
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.

Banshee777 Commited Dubber

74 posts · joined Jun 2015 ·

#1017069
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 Son of Jim - Creator of Good

2,506 posts · joined Jan 2009 ·

#1017072
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 👍

ragged Just ask if you need HELP!

478 posts · joined Jan 2005 ·

#1017080
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

Banshee777 Commited Dubber

74 posts · joined Jun 2015 ·

#1017082
Thanks guys, appreciate the feedback. I think I'll try for a better condition case to base a rebuild on.

Bizarre Moderator The artist formerly known as blue74l

12,785 posts · joined Aug 2002 ·

#1017099
Banshee777 wrote:. I think I'll try for a better condition case to base a rebuild on.
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!!!

ragged Just ask if you need HELP!

478 posts · joined Jan 2005 ·

#1017100
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

vlad01 Compulsive Aussie Vee Dubber

4,270 posts · joined Jun 2010 ·

#1017137
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

Banshee777 Commited Dubber

74 posts · joined Jun 2015 ·

#1017157
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 😎😂😂