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Chunky_t
Samba Member
Joined: June 11, 2025
Posts: 8
Location: Marlborough New Zealand
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 Posted: Fri Jul 11, 2025 9:25 pm Post subject: Unusual case cracks |
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Hey guys,
Just cleaning up my engine for a 65 beetle (F case) and noticed what looks like a rather large crack stemming from the casting mark on the top of the case at cylinder 1.
What's got me stumped is the marks around it, is it an old repair? Casting flaw? Doesn't leak to my knowledge.
Photos for reference. Possibly a devastating find as it's not a huge budget build.
Anyone have any ideas or seen cracks here before? |
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modok
Samba Member
Joined: October 30, 2009
Posts: 27656
Location: Colorado Springs
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| Posted: Fri Jul 11, 2025 9:35 pm Post subject: Re: Unusual case cracks |
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| I doubt those are cracks |
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Chunky_t
Samba Member
Joined: June 11, 2025
Posts: 8
Location: Marlborough New Zealand
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| Posted: Fri Jul 11, 2025 9:38 pm Post subject: Re: Unusual case cracks |
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| modok wrote: |
| I doubt those are cracks |
The one in the photos looks very crack like, not sure what else it is. Seems odd however. |
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modok
Samba Member
Joined: October 30, 2009
Posts: 27656
Location: Colorado Springs
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| Posted: Fri Jul 11, 2025 11:15 pm Post subject: Re: Unusual case cracks |
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Take a 1/2 ball or oval carbide burr and grind until it's smooth, then check again.
You don't need to do the whole thing, just pick the spot that you are most sure is a crack and hit that.
Soak with wd40, wipe it off, Pass a torch over it.
Or just fully degreasing with any aggressive detergent (12ph jetwash detergent) also tends to make cracks visible. |
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74 Thing
Samba Member
Joined: September 02, 2004
Posts: 7630
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| Posted: Fri Jul 11, 2025 11:44 pm Post subject: Re: Unusual case cracks |
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| Put a torch on it like suggested above and if there is a crack you should see it with the heat and case expansion. |
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mikedjames
Samba Member
Joined: July 02, 2012
Posts: 3304
Location: Hamble, Hampshire, UK
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| Posted: Fri Jul 11, 2025 11:49 pm Post subject: Re: Unusual case cracks |
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Looks like a casting flaw where metal flows into the mold but cooled before filling it fully. It has always been there.
Yes it is potentially a weakness in the case but because of its location (maybe over a thick part of the case) it has not leaked or done anything else for well over 50 years.
I would ignore it. Or if you like put JB Weld in the depression to make you feel better about it.
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Ancient vehicles and vessels
1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.
1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy |
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RWK
Samba Member
Joined: June 24, 2009
Posts: 1610
Location: S.W. MI
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| Posted: Sat Jul 12, 2025 5:19 am Post subject: Re: Unusual case cracks |
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Yes, casting flaws, we call them knit lines in the plastic molding business. same thing happens in the die casting industry.
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