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  1. #1
    Join Date
    Aug 2009
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    12

    Default 322 Nailhead Misfire Diagnosis

    I conveniently noticed that my engine was misfiring just as I was about to do a tuneup. I change the cap, rotor, plugs and wires to no avail. Cylinder #5 is still misfiring. It's getting a spark, so it's not the ignition system, and it's not the fuel mixture/carb since the rest of the cylinders are firing just fine.

    Any ideas?

    Thanks

    (1956 Buick)

  2. #2
    Join Date
    Jan 2004
    Location
    Lawrenceburg, Tn.
    Posts
    7,009

    Default Re: 322 Nailhead Misfire Diagnosis

    Yep, First, before you do any thing else,,,, run a compression test.....btw what is your name????
    Now, to the compression test,,, make a diagram of all the engines cyls.... then run the compression test and record the positions of the numbers for each cyl...
    1 cyl with low compression or no compression is indicative of possible burned valve, holed piston, stuck ring, or popped head gasket....
    2 cyls. that are low and side by side indicates a blown head gasket....
    all cyls. that are low indicates worn rings....
    random cyls that are low can indicate any of the above....
    The basics are this,,,, if a cyl has fuel, air, and compression,,, and spark at the right time,,, it has to fire.....
    You have fuel, air, and spark to that cyl,,,,is the spark at the right time???? tripple check the firing order of the ign wires.... then compression , or more correctly the lack of????? is all that is left.... look at the condition of the spark plug,,,, is it oily, damaged, white chalky looking[indicates water in the cyl], fuel fouled, cracked, or all of the above....
    But the compression test will tell you more about the engine condition than all the guessing that a man can do....
    You need a min of 90 psi.... on all cyls... for them to run....
    all the cyls need to be even....
    normal is 135+ or so....
    If the test shows low or no compression ,,,, there is only one thing to do ,,,, pull the head on that side and find out why.... once the head is off, ck the valves for being burned or warped, or the head cracked, or a blown head gasket....
    If none of those conditions are apparent,,,, then the piston/rod assembly has to come out for inspection,,,, looking for stuck or broken rings,,,''worm''holes caused by detonation,,, cracks,,, broken ring lands, cracked skirts, ect...
    A good compression gage can be bought, borrowed, rented, from your local auto supply store.... well worth the money...
    hope this helps....
    Doc "Widely unknown"

  3. #3
    Join Date
    Nov 2005
    Location
    Medway, MA
    Posts
    7,910

    Default Re: 322 Nailhead Misfire Diagnosis

    If you have compressed air, you can do a cylinder leakage test. This is the standard method of checking aircraft cylinders. Bring the piston in the cylinder to be tested to TDC on the compression stroke - obviously the valves will be closed. Feed about 75-80 psi of compressed air in through the spark plug hole - you can be a bit creative and make an adapter for an air chuck. I just busted the porcelin out of an old spark plug and welded an air line fitting to it. Remember that the piston will want to head for the bottom of the cylinder. hold the crankshaft pulley bolt with a proper socket and breaker bar. With the air cleaner removed, if you hear or feel air escaping through the carburetor, you have an intake valve issue. If you can hear or feel air coming out of the tailpipe (you will need a helper, or arms approximately 9 feet long to do this), you have an exhaust valve issue. If you remove the oil filler cap and hear/feel air coming out, you have a piston or piston ring problem. Remove the radiator cap (It's wise to do this at the beginning of the leakage test), If you see bubbles in the coolant (or have your own little "Old Faithful Guyser), you have a headgasket/crack in something expensive problem. This way you know what to expect before you get serious with the wrenches. Good luck!
    John Codman
    Formerly owned Buicks:
    '33,'48, '51, '52, '54, '55 (3), '56, '60 LeSabre 3 sp stick.
    264 powered '53 Mercury
    322 then 264 powered 55 Ford
    264 powered '56 Chevy
    Presently - 431 nailhead powered '82 C-10

  4. #4
    Join Date
    Aug 2009
    Posts
    12

    Default Re: 322 Nailhead Misfire Diagnosis

    I bought a compression tool and did the tests.

    CYL #1: 150
    CYL #2: 143
    CYL #3: 150
    CYL #4: 140
    CYL #5: 22
    CYL #6: 160
    CYL #7: 154
    CYL #8: 147

    I tried the wet compression test on the 5th cylinder but I think I put a bit too much oil in there as the compression went down to 0 and the car wouldn't stop smoking (still hasn't).

    Any ideas?

  5. #5
    Join Date
    Jan 2004
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    Lawrenceburg, Tn.
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    Default Re: 322 Nailhead Misfire Diagnosis

    Yep, pull the head that is on that side.... and start inspecting,,,, odds are that the piston and/or rings are good and you have a burned valve or warped valve... but also look at the top of the piston for holes or cracks....and at the cyl walls for score marks that run up and down....take a hard look at the old head gasket for evidence of being blown.... will be a dark stain around that cyl. somewhere... most likely with the rest of the cyls that high and that pretty well even the engine is in fair shape... you can do a ''used car lot'' job and just repair the affected cyl and put it back together and it will last a long time yet.... Yeah, I know that is cheaping out,,, but i believe in getting all the goodie out of an engine and then REBUILDING it rather than ''overhauling'' it....
    Doc "Widely unknown"

  6. #6
    Join Date
    Feb 2006
    Location
    New Hampshire
    Posts
    3,488

    Default Re: 322 Nailhead Misfire Diagnosis

    Let me guess, there is an exhaust leak @ #5 exhaust port, and you have a burnt valve...
    No, its not a chevy motor

    Steve Mario

    '71 Skylark, street/strip beater w/JW and T/A goodies!

    (JW prepped 462 short block, ported T/A Stage 1 TE heads w/stage 3 valves, 1050 Dominator, Super Scavenger headers, 3400 stall TH400, runs on pump gas, and leaves brown skid marks on the passenger seat.)

  7. #7
    Join Date
    Aug 2009
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    12

    Default Re: 322 Nailhead Misfire Diagnosis

    How much should a valve job cost on these cars if I find a good work-at-home mechanic?

  8. #8
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    Jan 2004
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    Default Re: 322 Nailhead Misfire Diagnosis

    Dont know exactly, shops charge different prices in different parts of the country....
    Doc "Widely unknown"

  9. #9
    Join Date
    Nov 2005
    Location
    Medway, MA
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    Default Re: 322 Nailhead Misfire Diagnosis

    I go along with Buickrat. I would also caution you that the valve job will be no better then the equipment that is used in doing it. Most work-at-home mechanics are not going to have top quality equipment in their basement. (Yeah, I know, some will sneak the job through on the equipment at their worksite. I have a problem with the ethics of that, and wouldn't ask anyone to do it). If it is a valve, I would pull the head and do a good three-angle valve job on the whole side. You will have the head off anyhow, why not carefully inspect all valves, retainers, springs, keepers, etc. You might avoid a very expensive failure down the road.
    "There's never time to do it right - there's always time to do it over."
    John Codman
    Formerly owned Buicks:
    '33,'48, '51, '52, '54, '55 (3), '56, '60 LeSabre 3 sp stick.
    264 powered '53 Mercury
    322 then 264 powered 55 Ford
    264 powered '56 Chevy
    Presently - 431 nailhead powered '82 C-10

  10. #10
    Join Date
    Aug 2009
    Posts
    12

    Default Re: 322 Nailhead Misfire Diagnosis

    UPDATE

    I did a leak down test and felt air coming out of both oil filler caps. That led me to believe I had a bad piston ring.

    However, I still removed the valve cover to inspect the rockers/springs. The #5 cylinder had a visibly bent intake push rod. This gave me some confidence and I began to tear the engine down (my first time). I removed the rocker shafts on both sides, then the intake manifold. The push rod had a 45 degree bend at the bottom, and the lifter was broken. I cut it with a grinder and pulled it out of there.

    I inspected the rest of the push rods and found two more that were slightly bent on the same side. The other side was fine.

    1. Could this explain the air coming out of the crankcase or is there still a chance I have a bad piston ring? The car was most likely driven like this for a while.

    2. Should I replace the three rods and the one lifter or should I do them all?

    3. oldbuickparts.com (Cars INC) is the only place I can think of to source the parts. Is this the best source or is there another?

    Thanks for all the help.

  11. #11
    Join Date
    Jan 2004
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    Lawrenceburg, Tn.
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    Default Re: 322 Nailhead Misfire Diagnosis

    Pull the head and inspect the piston/ cyl wall..... I think you may find a lot more damage....
    Doc "Widely unknown"

  12. #12
    Join Date
    Jul 2003
    Location
    MI
    Posts
    815

    Default Re: 322 Nailhead Misfire Diagnosis

    Those bent pushrods could have been caused by some valves being stuck. At this point I think I'd pull the heads and at least have a look at #5 cylinder wall. When you pull the broken lifter out, check out that cam lobe. As far as engine parts, I used Egge in California. They had good customer service and were as reasonable as any. You could also use Bob's Automobilia, and there are some good Nailhead guys on this board who may know others. If you do decide to just replace even one lifter, break it in like you were replacing the whole cam and lifter set...1500-2000 RPM for 30 minutes. Use some Brad Penn break-in oil. If this car was sitting for a long time and wasn't looked after well, don't be surprised if you have to replace a lot more stuff than just this. Good luck--keep us posted...
    1953 Buick Special Riviera! 263 I-8
    1965 Skylark 300-4V
    1965 Mustang 289
    1965 Corvair Monza Convertible
    1965 Dart 170 Wagon

  13. #13
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    Jan 2004
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    Lawrenceburg, Tn.
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    Default Re: 322 Nailhead Misfire Diagnosis

    Aaron, I am thinking that he may have blown a piston down over the rod, but it should be making a bunch of noise with the wrist pin hammering up and down the cyl wall when the engine is turning over....maybe it is not that bad yet....definitly need to pull the head to look at the piston/cyl wall..... yep....
    Last edited by doc; 08-12-2009 at 07:33 AM. Reason: mo info
    Doc "Widely unknown"

  14. #14
    Join Date
    Aug 2009
    Posts
    12

    Default Re: 322 Nailhead Misfire Diagnosis

    It if turns out to be a bad piston/piston ring, would I have to rebuild the entire block or just the one cylinder? Do I pull the block out or can this be done in the car?

    Also, the rocker arm was completely loose and was not being pushed up at all, which would mean the valve was closed the entire time. I manually pushed on it, along with the others, and it moves as much as they do, so I don't think it's stuck. And since it was closed, could it be responsible for the bad compression?

    If removing the head is as simple as unbolting the exhaust manifold and head and reinstalling with a new gasket, I will give it a try.

  15. #15
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    Jan 2004
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    Lawrenceburg, Tn.
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    Default Re: 322 Nailhead Misfire Diagnosis

    I think,think, that the head can be removed with the engine in the car,,,,now if the piston is damaged, it can probably be removed with the engine in the car.... you will most likely have to take the motor mounts loose and jack the engine up some to remove the oil pan....to get to the rod bolts.
    Now back to the head,,, you should be able to just take the 2 exhaust pipe bolts loose , then the head bolts, and then just lift the head/exhaust manifold off together,,,, they will be heavy,,, dont get a hernia here,,,,
    then get the no.5 piston down to the bottom of the stroke and inspect the cyl walls REAL GOOD....and the piston REAL GOOD....be advised, if the piston has busted all to pieces , you need to look at the cast in oil galley that runs down the center of the engine,underneath the cam, to make sure it is not damaged,,, but come to think of it , it probably isnt because you have had the engine running recently, and it had oil pressure then....so the galley should be intact....
    When a nailhead busts a piston all to pieces the fragments can fly up and knock a chunk out of the oil galley,,,,,destroying the block....They can be salvaged but it is expensive....
    Doc "Widely unknown"

 

 

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