Help needed: How to remove OEM spark plug?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by 2009Prius, Aug 29, 2010.

  1. 2009Prius

    2009Prius A Wimpy DIYer

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    Continuing from this thread which I accidentally posted in the "main" forum.

    http://priuschat.com/forums/gen-ii-prius-main-forum/83929-spark-plug-inspection-2.html#post1173220

    I had trouble unscrewing the spark plug even though the advertised torque is only 13 ft-lb and the car is only 13K miles 1.5 year old.

    I googled "spark plug stuck" and read some posts on line.

    Lots of horror stories of broken spark plugs and stripped threads - big $$$ to repair.

    Some suggest warming the engine but others caution that would soften the aluminum and make it even easier to strip the thread.

    Some suggest WD-40, PB, motor oil etc. to soak and lubricate.

    Some suggest to check if the socket rubs on the wall.

    Any other suggestions to take out the plugs safely?

    What's the max safe reverse torque? Thanks!
     
  2. GasSaver1

    GasSaver1 Member

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    why do you suspect water leaking in or corrosion at only 13000 miles on a car that is a year old this is going to create risk and could lead to more harm than it ever could solve.

    edit:
    I am all for playing around with cars but there are just some things you dont mess with for no reason. All the cars I ever had got way past 100k before the plugs had to be changed and that was just via regular service not because they failed. When you pull that plug out you will have a direct opening to your cylinder. If dirt falls in there you are going to scratch the wall and lose compression. You will need an engine rebuild to fix this. If you screw up taking the plug out (of a COLD engine which it should be) you will strip the threads and need to have it fixed with a helicoil which will require drilling into the engine block. Remember that direct hole from before? Now there is a greater chance of metal shavings getting in there during the repair.

    If you screw up putting the plug back in you will crossthread it and will have to go through the same helicoil fix + have to worry about where the shavings created by the cross threading went (like in the direct hole)

    If one of the reasons for this is to put antisieze on the plug so it doesnt get stuck- well its stuck now so you would not be preventing anything not to mention putting something on the threads is standard practice and I am sure toyota already lubed it up for you. Will forcing it out cause shavings to fall into the cylinder? Could be, would you really want to risk that?

    There is a lot of preventative maintenance you can do for a car, this- especially due to the number of miles and the age of the car- is not such maintenance
     
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  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The force that you can exert by hand, using a 1/2" socket wrench.

    As long as you are turning CCW to remove, don't worry. The worst that will happen is that you'll destroy the spark plug by snapping off the porcelain tail, if the socket is not lined up perfectly on the spark plug hex.
     
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  4. 2009Prius

    2009Prius A Wimpy DIYer

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    Well I confess I read too many PriusChat posts. :p

    And too many other posts on-line. :p The question is whether the plugs get stuck in there after a long time. So some people suggest periodic removal.

    I was wondering about this too. I suppose I could vacuum it before putting the plug back? How big a piece of dirt would make a difference? There are plenty of microscopic dusts floating in the air visible under strong light. Those are impossible to get rid of but presumably they are too small to matter? The engine is not manufactured in a clean room environment or is it?

    At any rate I am glad I chickened out at the last minute. Maybe I will leave this part to the dealer. :)
     
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I am not glad that you chickened out at the last minute. :mad:

    This really is not a big deal. Although it's not necessary to remove the plugs now, I think that you should put that on your to-do list when the car has 60K miles, for fun.

    <Or do it sooner if you need more fun in your life now.> :rockon:
     
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  6. GasSaver1

    GasSaver1 Member

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    Honestly it doesnt take a lot of anything in the cylinder to cause big problems. Remember there are only 2 "natural" entry points: Fuel and Air but both of those have entry points far from the cylinder (gas cap and air intake) and both of those run through a filter prior to the cylinder. These filters are so important for this exact reason. At the end of the day you dont want anything in that cylinder that is not suppose to be there.

    When I owned a 300zx I had plenty of fun pulling the engine apart for repairs and upgrades. That car had close to 150k miles on it when I sold it and the plugs were fine. The only time I actually pulled the plugs was during compression tests. Granted that was slightly more dangerous because you have to disconnect the fuel source, pull ALL the plugs and then screw in the tester into each cylinder one at a time and crank the engine- but anytime I caused an unprotected entry point it was scary. Then to test to see if you have bad rings or a messed up cylinder you have to put a few drops of oil into the spark plug hole and check again (the oil would cause a better seal of the piston rings so if the rings are bad and you do that the compression number would increase, of course when it is all back together the oil would burn out). This is done if just one cylinder has a low compression number. If two cyclinders have a low number that are next to each other you may have a blown head gasket which is the seal at the base of the cylinder. Other possible symptoms of that include burning oil or coolant- or having what looks like a bit of chocolate milk in your oil (which is what happens when you mix oil and cooland togrther)

    You can, and have to vacuum it out but you see the size of a spark plug, the hole is not very big it creates. It is hard to get a vac down there and if you miss something you wont know. If you do damage something you might not find it with these cars for a long time. I wrote out the tests with the 300zx to show that it is hard to find little problems here. They involve compression tests or oil analysis unless you see the obvious burning oil or chocolate milk which probably wont happen unless you have a lot of damage. You will normally notice a lack of power or rough engine while running. The problem is with OUR cars it might be hard to diagnose engine compression problems because the battery boosts the gas engine and it isnt like the engine is idling to see the deal.

    If you lose a spark plug, I am sure you will know it. The engine will not have a cylinder firing and you will feel the unusual vibrations at ALL time when the engine is running on gas (not the strange shutting when it just turns off). So dont worry about the plugs unless you need to-

    I dont want to destroy people's want to DIY and think it is great! just, there are a ton of risks involving the engine and what could go wrong, all of which will be hard to diagnose\very costly to repair problems so in this instance I would recommend caution
     
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