Mazdaspeed3 cam shaft not turning

Discussion in 'Mazdaspeed 3 Troubleshooting' started by Alex harris, Apr 15, 2023.

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  1. Alex harris

    Alex harris Greenie N00B Member

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    Picked up a MS3 car turns over but sounds poor and won't start. Compression test came back bad. Pulled the valve cover off and found out the intake cam will not spin with the crank or exhaust cam. But I can spin the cam by hand with a wrench. Not sure what I should do, new intake cam, new vvt sprocket? Should I pull the head and check all the valves? When turning over did not sound like the valves were hit. Not sure what I should do if anyone can help that would be awesome!! I do have a video of the car turning over
     

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    Alex harris, via a mobile device, Apr 15, 2023
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  2. Easter Bunny

    Easter Bunny Professional Engineer Motorhead Platinum Member

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    The cam gear has special friction washers between it and the camshaft that can be finicky to install. My guess is that someone did a vvt replacement and screwed up.

    You will need new friction washer and to retime the motor at a minimum.

    I don't know how you wouldn't have any bent valves but you would want to pull the head to be sure
     
    Easter Bunny, via a mobile device, Apr 15, 2023
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  3. L337TurboZ

    L337TurboZ World Class Truck Squatter Silver Member

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    Here's my suggestion.

    You obviously have to re time the engine. If you can have access to a leak down tester then remove the timing cover, valve cover, chain, and camshafts.

    Then use the leak down tester to check each cylinder. If the leak down is within acceptable limits you probably don't have a bent valve. If it isn't then you're already on the way to pulling the head off. All that's left at that point is the turbo and intake manifold.

    If leak down checks out reinstall the camshafts and use the proper timing tools to set timing.
     
    L337TurboZ, via a Motorola device, Apr 15, 2023
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  4. Alex harris

    Alex harris Greenie N00B Member

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    Okay thank you. I couldn't find anything online on how the sprocket connected to the intake cam. Would it be worth buying a new vvt sprocket?
    I'm in the process of taking the intake manifold off, would i be able to tell if a valve is bent by just peeping in?
     
    Alex harris, via a mobile device, Apr 15, 2023
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  5. Easter Bunny

    Easter Bunny Professional Engineer Motorhead Platinum Member

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    The sprocket should be fine unless it has been spun a lot and gotten the face fucked up from being loose.

    Intake is only half the valves and will be tough to tell if anything is bent unless it's seriously bent. Compression test is your best bet
     
    Easter Bunny, via a mobile device, Apr 15, 2023
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  6. Alex harris

    Alex harris Greenie N00B Member

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    Okay thank you. I'm gonna get a new friction washer and a vvt just to be safe. Thank you for the help just got done building my st that felt less complicated
     
    Alex harris, via a mobile device, Apr 15, 2023
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