OEM Head Gasket for 88mm bore?

Discussion in 'Mazdaspeed 3/6 Engine' started by Stephen Stites, Jul 2, 2023.

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  1. Stephen Stites

    Stephen Stites Greenie N00B Member

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    Hi everyone!

    As the title states, can I use the OEM head gasket on my 88mm bored block?

    Background in case you're interested. I rebuilt my blown Speed3 with a complete gasket kit from RockAuto. Amateur mistake, I know. I needed 1 new sleeve and had all cylinders bored out to 88mm. Everything seemed fine for the first ~3000 miles, but last month it overheated. I found oil/coolant mixture in the lines, and most of that milkshake mixture was leaking out two loose coolant lines (pic included). I'm assuming the head gasket failed and pressurized the coolant system, causing those two lines to pop. I'm still working on picking apart the motor to actually find the failed part.

    So I'm doing a head gasket replacement, and not with cheap parts this time. I need to decide if OEM will work, or get the 88mm Cometic gasket. Naturally, I am also getting new head bolts, friction washers, etc.

    Thanks for your time!
     

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  2. SyntheticAtmosphere

    SyntheticAtmosphere You only get ONE ride, ONE ticket, ONE time! Silver Member

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    Cometic is the way. Its in my list of goodies without doubt and so many have had success with it.
     
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  3. Awafrican

    Awafrican Moderator Gold Member

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    +1 for cometic
     
    Awafrican, via a mobile device, Jul 2, 2023
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  4. Cfoldone

    Cfoldone Gold Member

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    +2 for Cometic-- have on both my rebuilds. Especially if you get deck and head machined flat for the different thicknesses.
     
    Cfoldone, via a mobile device, Jul 3, 2023
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  5. Raider

    Raider Administraider Administrator Platinum Member

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    Cometic. If head and block skimmed find out how much so you can get the right thickness. I did. Edge had it in stock.
     
    Raider, via an iPhone, Jul 4, 2023
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  6. Scaytale

    Scaytale Gold Member

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    I like cosmetic gaskets, used it on the supercharged NB Miata for years.
    However if $$ are an issue, you can use the OEM Speed3 head gasket, up to 89 mm, according to speedperf6rmanc3.com.
    I used the OEM 2.3 Speed head gasket when I did the 2.5 Bottom end swap, has about 200 miles in it, no issues, running stock boost levels right now but plan to bump it up to 18-20 once I get the tune evened out at Stock levels.
     
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