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Thread: 3.1 3100 Top End Issue- push rod length?

  1. #1

    3.1 3100 Top End Issue- push rod length?

    First time posting here, so please be gentle if Im in the wrong area. Also I would like to note I did a search and didnt see what I was looking for.

    I have a 1997 Buick Century with the 3100 in it. I had a coolant leak in the winter and didnt fix it. In the end it ended up biting me in the arse. THe head gaskets blew and the heads warped. Theres the background.

    Ok so I buy heads from www.marshallsautoparts.com. I buy the head & intake gaskets. I spent about 15 hours putting it back together. I finally get it all back together tonight.

    Start it up...

    And she knocks!

    Now it never knocked before! My Uncles friend helped install the pushrods. He now thinks we may have misplaced one.

    So my question is, are all the short rods intakes or exhausts?

    If there is just one set swapped did I damage a valve?

    And the bonus question, would anyone like to redo/fix this for me as Im so mad right now!!! lol, silly I know but Im so discouraged!

    HELP!

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  3. #2
    The Master Piece Syn's Avatar
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    Re: 3.1 3100 Top End Issue- push rod length?

    Quote Originally Posted by Ryan from Ohio
    First time posting here, so please be gentle if Im in the wrong area. Also I would like to note I did a search and didnt see what I was looking for.

    I have a 1997 Buick Century with the 3100 in it. I had a coolant leak in the winter and didnt fix it. In the end it ended up biting me in the arse. THe head gaskets blew and the heads warped. Theres the background.

    Ok so I buy heads from www.marshallsautoparts.com. I buy the head & intake gaskets. I spent about 15 hours putting it back together. I finally get it all back together tonight.

    Start it up...

    And she knocks!

    Now it never knocked before! My Uncles friend helped install the pushrods. He now thinks we may have misplaced one.

    So my question is, are all the short rods intakes or exhausts?

    If there is just one set swapped did I damage a valve?

    And the bonus question, would anyone like to redo/fix this for me as Im so mad right now!!! lol, silly I know but Im so discouraged!

    HELP!
    well i am about 40mins north of detroit i'd come help but its gonna require some $$$ anyways when i bought all my 3400 stuff for my hybrid all my pushrods were the same length. but i can't use them since a hybrid requires custom length so if u need new ones i have some.

    also did you check to see if any were bent? also if the coolant leaked inside of the motor it could be something worse.

    drain the oil and look for coolant/milkshake


    1993 Cavalier Z24, 3.1/3400 hybrid, crane 272 cam, LS6 springs,port and polish,2.5 exhaust to 80 series flowmaster,solid mounts

  4. #3
    If pistons have hit valves, then there is a VERY good chance that the head will have to come off, and you'll have to buy a valve. Depending on how much interference there is, this could easily have damaged the piston, too. I've seen it happen lots of times.

    Here's what I'd do. First I'd check and see if pushrods are out of place. Take the valve covers off, check to see which rockers are all the way up- you should be able to spin the pushrod by hand when the valve is all the way up. Turn the engine with a big ratchet or something and make sure that every single pushrod becomes appropriatly loose (can be spun by hand) when each piston is at TDC COMPRESSION. If one pushrod stays tight, then you've likely found the valve the long pushrod that's out of place (I don't know how you'll find the short one... maybe it'll actually be loose).

    Also, check as you turn the engine over by hand- if a valve is actually hitting a piston, you may feel it bind in one spot. Of course this may not be an issue anymore since the engine has been run this way and may have 'self-clearanced'.

    Anyways, if you find an out of place pushrod, and are confident that you can swap everthing back into the right position... I'd personally do a compression check on all the cylinders. If the compression on the cylinder with possible valve-piston contact is the same as all the others, I'd start it and see how it runs. If the compression checks good and it runs good, then you might have gotten away with it. I've seen stranger things.

  5. #4
    Captain of the Failboat SappySE107's Avatar
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    You can't spin any pushrods by hand unless its not right. That or your hands are much stronger than mine.

    Intake valves are short from what I remember.
    Ben
    60DegreeV6.com
    WOT-Tech.com

  6. #5
    The longer pushrods are the Exhaust and the shorter pushrods are the Intake.

    When I did my swap I noticed something that I had not seen mentioned before. What I noticed was that the exhaust pushrods seem to go behind the gasket where as the intake or the shorter pushrods sit on the outside of the gasket.

    Looking at this picture at the front head you can kind of see what I am talking about. The proper order for the front head starting from the left hand side would be E, I, I, E, I, E The rear head starting from the left would be E, I, E, I, I, E

    2000 Grand Am GT
    2011 Chevy Impala

    "The world's best cam combined with a poor set of heads will produce an engine that's a dog. But bolt on a set of great heads even with a poor cam, and that engine will still make great power." ~John Lingenfelter

  7. #6
    Quote Originally Posted by sappyse107
    You can't spin any pushrods by hand unless its not right. That or your hands are much stronger than mine.

    Intake valves are short from what I remember.
    Ok, let me clarify a bit. The pushrods may not spin by hand if you're a wuss. If you're not a wuss, then the pushrods should spin by hand with a little effort when the valve is up- it might help to use a rag to get a good grip.

    Forgot to mention- if you find that you have pushrods out of place, make sure they're straight before you put'em back in. Roll them across a metal table or something- it'll be obvious if it's bent.

  8. #7
    The Master Piece Syn's Avatar
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    the pushrods won't spin easy they'll have a slight drag on them

    we all know why you can spin em so easy


    1993 Cavalier Z24, 3.1/3400 hybrid, crane 272 cam, LS6 springs,port and polish,2.5 exhaust to 80 series flowmaster,solid mounts

  9. #8
    Ok thanks for the info so far.

    Im pretty sure we put all the short rods on the intake as noted- well except the one his friend did. That one is in the back by the power steering pump, so #1...

    Ok. Since I got everything back together and all that good stuff what is the easiest way of getting to it. Ive been told I dont need to take anything off but the valve covers to check.

    I guess if I pull the plugs I could probably tuen it over by hand... My dad told me to turn the car on and listen to it with a screw driver... THen I know which one to really tear into/look at.

    Advice please

  10. #9
    The Master Piece Syn's Avatar
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    just take the valve cover off and remove the rocker you should be able to get to the pushrod


    1993 Cavalier Z24, 3.1/3400 hybrid, crane 272 cam, LS6 springs,port and polish,2.5 exhaust to 80 series flowmaster,solid mounts

  11. #10
    You got that right syn... Just wait 'til you get married- you'll see.

    Them pushrods should spin- I never said they'd spin EASY. There will be a significant drag, but if you can't spin'em when the valve is closed, there's something WRONG.

    Unless of course you don't bother to lube the ends of the pushrod when going back together- then maybe you won't be able to spin them. They'll spin easy enough soon as they get oil though.

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