Head gasket ?

Discussion in 'Shop Talk' started by Rob30, Sep 10, 2006.

  1. Rob30

    Rob30 Well-Known Member Supporter

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    I am changing my head gasket on a cavalier 2.2 engine. Should I be able to see where the failure was? While it is apart is there anything else I should be looking at? I am going to clean out the carbon while the head is off. I'll be putting it together tomorrow, after I go to town and get a gasket.
     
  2. moopups

    moopups In Remembrance

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    The failure area should be visible, in the form of separated laminations or similar. There will be visible leakage signs. Also check the head for warpage, such as with a straight edge such as a carpenters square over its entire length, any more that a couple of thousands of an inch indicate the need for corrections such as machining.

    Placing the head on a sheet of glass with valve grinding compound, moving it in a figure 8 pattern will quickly show areas that need attention.
     

  3. agmantoo

    agmantoo agmantoo Supporter

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    Depends on the problem you are having with the head. If you are getting coolant into the cylinder you should be able to see which cylinder has the problem by looking at the sparkplugs. The one with the coolant will be cleaner. With the head off the piston with coolant will be clean also. If you have compression leaking it will be as moopups posted. I think you will also need more than a gasket, such as new headbolts. I would also check the timing belt, tensioner and the waterpump (I think this is a belt driven cam). If these items have a lot of miles I would change them also while in there. Get your timing marks aligned prior to removing the head then do not rotate the engine until the gasket replacement is finished
     
  4. Northman

    Northman Well-Known Member

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    2.2 is not a OHC engine agman.
     
  5. Rob30

    Rob30 Well-Known Member Supporter

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    I drove the car home (about 1 hour). After putting in some rad stop leak. Seems to have sealed it. There was anti freeze in the oil when I added the stop leak, and non when I was home. So I don't know if this is why I don't see evidence of the leak. I know cylinder 2 was very low on compression about 60 pounds, cylinders 1 and 3 about 90 pound and cylinder 4 was 130 pounds. This all started when the car overheated because the heater core started leaking. Thats a whole other problem. Its harder to change than the head gasket.
     
  6. agmantoo

    agmantoo agmantoo Supporter

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    Rob, if the car will hold anitfreeze without the radiator cap on securely leave the cap loose so it cannot build pressure. This will aid the sealant in containing the coolant.

    Northman,
    I think it depends on the year model as to whether it is OHC or not! Either way depending on the mileage, he may need to change the belt or the chain for the timing.
     
  7. Rob30

    Rob30 Well-Known Member Supporter

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    I have it all back together now.
    I will be trying it out tomorrow.
    The cavalier came with two 4 cyl motors. The 2.2 for economy, and a 2.4 for performance. The 2.4 is a OHC engine. Also much worse on gas and not as dependable, so I have been told.
     
  8. skruzich

    skruzich Well-Known Member

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    Before you fire it up, unplug the coil plug and do a compression test on each cylendar. That way you will know if you fixed the problem. I am not sure on the headbolts whether or not their torque to yeild bolts or standard headbolts. IF their torque to yield, you must replace them as well as have a dial guage to torque them properly.

    Since you overheated it, the head warped. The gasket may not have failed, but any warpage in the head will create a gap that the antifreeze can slip past the gasket. Usually it will create a fissure in the gasket.

    Most importantly, did you check the head for cracks near the valves. I personally take them in and have them magnifluxed before putting them on. That solves that problem, and if i have reservations on the magniflux, i have them pressure tested after machining the head.
     
  9. Rob30

    Rob30 Well-Known Member Supporter

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    I checked for warpage with a strait edge. I did not find any.
    I will do a compression check in the morning, good idea.
    As far as getting the head checked by the machne shops, thats a little inpractical here. Shop rate is about $75/hr, and I can pick up a used head for about $50. I bought the whole car 4 months ago for $500.
     
  10. skruzich

    skruzich Well-Known Member

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    Hopefully you got lucky on the overheating, most heads will crack between the valves. Their usually hairline cracks but thats all it takes to lose compression.
    IF you find your compression is low then do a leak down test. You put compressed air into one cylindar and check to see if you have air leak out.
    You will hear it.

    The main thing is if you find theres a problem with the head before you fire it up, you can save yourself the cost of a new headgasket. You can reuse the head gasket if you don't fire it up and heat it.
     
  11. Rob30

    Rob30 Well-Known Member Supporter

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    I talked to a mechanic today, he suggested doing a compression test after adding a little oil to the cylinder. He stated that that will tell me if it is a valve leak or a ring leak.
    But I don't seem to be looseing antifreeze into a the oil anymore.
    The mechanic also said I t might be easier and cheaper to find a used engine for the car.
     
  12. agmantoo

    agmantoo agmantoo Supporter

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    Do a before and an after compression test with the oil. Keep records by cylinder. This oil will help identify whether the low compression is from worn rings or bad valves. The stop leak could have sealed compression leaks also ( I am confused as to what you have done thus far regarding the gasket and coolant). Did you reuse the coolant that had the stopleak additive? PS... Have all sparks plugs out when doing the test.
     
  13. Rob30

    Rob30 Well-Known Member Supporter

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    I took out the spark plugs and did a compression test. The compression is good in all cyinders. When I tested with the plugs in, the compression is low.
    I never remove the plugs for a compression test. Whats the difference?
     
  14. agmantoo

    agmantoo agmantoo Supporter

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    With the plugs out the starter will turn the engine at a uniform RPM for each cylinder. With the plugs in, except for the cylinder under test, the cylinders that have the plug in will influence the reading as the RPM will vary due to the conditon of the cylinders. Taking ALL the plugs out is the proper way to do the simple compression test. What were the readings of the individual cylinders with the plugs removed?
     
  15. Beeman

    Beeman Well-Known Member

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    You are also supposed to hold the throttle body or carb wide open while cranking to allow full air flow. This is for an accurate test comapring cyliders eeficiency. Obviously when you get a large variation it would still show up without removing plugs or holding the throttle open.
     
  16. Gideon

    Gideon Well-Known Member

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    A simple country way to check the head for leakage is to lay it down with the motor side up. Fill the valve areas with gasoline and see if it leaks out. Not as good as magnifluxing but if the valves are leaking it will quickly show up. If a minor leak you may be able to finish the valve matching surfaces yourself with paste and twisting under pressure. Have seen it work and saves time/money. Nothing really lost if it does not solve the problem.
     
  17. Rob30

    Rob30 Well-Known Member Supporter

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    Before taking out the plugs the readings were all over.

    I don't understand the simple country test.
     
  18. Beeman

    Beeman Well-Known Member

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    I can't say whay your readings were "all over" before removing plugs unless either the batt is low and cranks slowly or you didn't count pulses or revolutions of the engine while cranking it over.

    The "simple country test" is just pouring gas, water or any other light liquid into the intake and exhaust ports and seeing if it leaks out past the valve seats. Can also do it the other way and fill the combustion chamber and see if it leaks into the ports.
    You have an aluminium head so they wouldn't magnaflux it, a good machine shop would have plates with rubber gaskets which bolt to the head. They then submerge the head in water and apply air pressure, bubbles would indicate a leak like checking a tire.
     
  19. skruzich

    skruzich Well-Known Member

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    140 lbs pressure, slap the plugs back in, smack it on its grits and call it fixed.
     
  20. Rob30

    Rob30 Well-Known Member Supporter

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    I've put about 600km on th car since the fix. No noticable problems, no anti freeze in the oil etc. Only problem is the check engine light is on.