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Thread: rover V8 cylinder head showing internal crack?

  1. 7th December 2023, 07:23 PM #1
    prelude
    prelude is offline Wizard Supporter
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    rover V8 cylinder head showing internal crack?

    I took the heads off my V8 since I had a problem with one of the freeze plugs and I can't really get to the back ones in situ to find that the plugs seem to be fine. Since I was losing coolant back there I checked the gaskets which did not show any problems but upon closer inspection of the coolant channels I found this:

    IMG_6994.jpg

    This appears to be a crack or a seam in the casting. The head bolt hole next to it also shows a seam but it is further down and the headbolt itself is pristine so I reckon it is not leaking there. Is this crack/seam something that every head has? or am I looking at a potential problem?

    This is from a GEMS 4.6 V8 ie a very late cast in the V8's life.

    Cheers,
    -P
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  2. 8th December 2023, 04:12 PM #2
    PLR
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    G`day ,

    looked in a couple both have similar on outer sides inside the jacket the newer casting is rougher , looking like arc spatter one end .

    You could pour some thinners type thin fluid in it with the head on an angle but i think it will just evaporate and not flow anywhere .

    The heads

    HRC2479 date stamp 05 94

    HRC2479 date stamp 03 97

    Both in your GEMS range .
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  3. 9th December 2023, 08:03 AM #3
    PhilipA
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    To me it just looks like a casting mark. The latest heads were much worse than the early ones particularly in the exhaust ports.
    I came to the conclusion that water loss at the back of the block is from the block relaxing into a bow in the middle with the ends down, so that the head gasket would not seal.
    I couldn't stop mine leaking at the ends.
    Regards PhilipA
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  4. 14th December 2023, 11:43 PM #4
    prelude
    prelude is offline Wizard Supporter
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    thnks guys

    I am currently putting the heads back on and going to check if the leaks were fixed. Turns out that the freeze plugs tend to leak for various reasons. I just replaced all of them (on the heads). Here's hoping it will stay closed.

    Cheers,
    -P
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  5. 28th December 2023, 06:44 PM #5
    prelude
    prelude is offline Wizard Supporter
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    Update time!

    My first freeze plug removal was a bit of a hack job since RPI used fairly thick staino plugs which do not bed well and come out easily (since they are only 20mill) but the other 3 I got the hang of it so minimal damage was done to the ali. I used a bit of liquid sealant, that black stuff to make sure the small scuffs in the ali would not cause a leak and seal the new freeze plugs well. The engine has since done a few runs and has come up to temp and thus pressure. It is winter time down here so mid summer extreme temps is yet to be seen, though in theory it should not be that much hotter since the thermostat should regulate the temp.

    Another problem solved!

    Cheers,
    -P
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