Compression test 01 Navigator

Discussion in '1st Gen - 1997 - 2002' started by Fordgirl01, Jul 28, 2019.

  1. Atman246

    Atman246 Full Access Members

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    As was said,check the valve spring. An easier way to locate the leak in the cylinder is to put air in and listen for the hissing. It's like a compression test in reverse. In the compression tester,there's a Schrader valve that needs to be removed. It's like the valve in a tire valve stem. Remove it,screw the compression tester into the plug hole and hook it up to a compressor with regulated air flow. Awesome job girl. Who needs a manicure?? My wife is 58 and runs a woodsplitter and a straight shaft weed wacker. That's what I brag about..
     
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  2. Fordgirl01

    Fordgirl01 Full Access Members

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    Ok-I manually turned the camshaft that the roller was under to get the teardrop shape on top. I did notice a scratch. I can feel it slightly when I rub my finger over it. Should that camshaft be replaced for a scratch like that (it’s like maybe a fingernail scratch-maybe a little deeper)? Also-I can’t see where that spring is broken. I even put the inspection camera down there. However, that spring seems shorter, more compressed than the other 15 springs.

    I certainly want to do everything right considering how difficult it is to access this area-I don’t really want to do it again!

    Thank you again everyone for your patience and knowledge [​IMG][​IMG][​IMG]


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  3. Fordgirl01

    Fordgirl01 Full Access Members

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    Sorry about the repeated quote. I know how to edit posts but can’t seem to figure out how to delete it when I do that!!


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  4. stamp11127

    stamp11127 Super Moderator Staff Member

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    Reply deleted.

    To do things right the cam should be replaced. Will it run without replacement? Yes, if the scratch has gone deeper than the hardening it will flake off small pieces of metal as it wears. That in turn can take the entire engine out if not caught by the oil filter. Plus you will have accelerated cam lobe wear.

    Since the valve spring is possibly shorter than the others you may be able to move it up and down some in the head. If so, it is valve spring replacement time - with your fingers crossed the valve & seats aren't damaged.
     
  5. Fordgirl01

    Fordgirl01 Full Access Members

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    I can’t budge the spring. I even tried prying it a little and it doesn’t move. I would prefer to do this right as I intend to keep it-it’s rust free and not really high mileage.

    So-how hard is a camshaft for this thing to come by? I did a quick search but nothing serious yet.


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  6. 1955moose

    1955moose Full Access Members

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    Try Parts Geek for your camshaft. I keyed in 99 Navigator, and they have cams that pop up.

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  7. stamp11127

    stamp11127 Super Moderator Staff Member

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    Don't get a cam just yet, you still need to determine why there isn't any compression in that cylinder. If it isn't from a leaking valve then it is in the bore.
    If you can the next step would be to bring the #8 cylinder to tdc and hit it with compressed air through the spark plug hole. Where you hear the air leaking tells you where the problem is.
     
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  8. TobyU

    TobyU Full Access Members

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    Now we are getting somewhere.
    Usually when a follower/rocker pops off ( well ,maybe not usually but often) there is no valve spring or seat (popped) or cam damage.

    Compression is a funny thing. I can't remember from the previous page pics if it's an intake or exhaust valve we are concerned about.
    If we have sealed closed valves....If an intake follower is off ...you can't suck any air in for it to compress so you will have very low reading.
    If exhaust then you will have plenty of compression as it compresses the air the intake valve lets in but you get another compression on the exhaust stoke as it can't exit through open exhaust valve.

    An intake will cause the needle (on most gauges) to go up and suck back down hard then back up instead or pulse up up up.
    It will also suck really hard if you put a hose or rubber plug on a stick down there.
    This is what I was talking about way earlier in the thread.

    The valve spring looking lower concerns me.
    That would mean it is not coming up (closing) all the way. This is usually from a popped valve seat, or slipped valve guide or bent valve on engines in general but I have never seen any of these on a ford modular so I don't know what it most likely.

    As Stamp ans others have said, now you need to put air into the plug hole to see where it comes out.
    My guess (unfortunately) is you will hear air escaping out intake or exhaust. I'm guessing exhaust.
    10-15 psi should do it don't crank it wide open into it.
    You can push down on the valve when the air is going in and hear the air flow then be sealed off.

    It is possible to have a broken spring too (are those dual or single ones?) and the valve be stuck by the spring. That right now would be your luckiest thing.

    The air is what you use to hold the valves for that cyl closed if you remove the spring.

    If you have sealing valves and no broke springs and the cyl holds air then you I would put a new follower and lifter(they call them lash adjuster I think)as you can't trust the old ones and they are cheap parts even at Ford dealer.
    THEN you do compression test and it you get 120 + you are happy.

    If this were the case I would not worry about the cam scratch.I would dress it with an emery board (I use them all the time but not on my nails) then a red scotchbrite pad to polish it then some metal polish or a dremel polish wheel but a rag and your finger with polish will be ok.
    That lifter roller wheel is very hard and there is little friction between the two.
    If everything goes in your favor and you don't have to pull cam or head and you keep the cam just run some full syn oil in it.

    If it doesn't hold air or if you have to investigate spring much I think you'll have to pull cam on the dreaded 32v to see anyway. If it's out you and you fix the rest you can probably get a used cam fairly cheap---BUT 32v again so what do I know.
    I hate them even though I have one in the driveway. Give me a 4.6 (YEAH) or a 5.4 16v (less YEAH) any day!!

    Good luck and GREAT job so far!!!!
     
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  9. rjdelp7

    rjdelp7 2000 XLT

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    I don't see how a scratch on the cam, makes it bad. Its a roller follower and is covered in oil. The scratch is in direction of movement, not across the lobe. The video on youtube, has a guy wrenching, that claims the exhaust valves leak on these motors. He doesn't explain why. A another guy on youtube claims, fixing a poorly maintained Ford modular is a waste and always replaces them(that is what dealers usually do). My guess is, it probably burns a lot of oil and got ran one too many times low. So you can go through all this trouble and have more problems. If its the spring, fix it and put back together. Don't get in, upside down on it.
     
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  10. stamp11127

    stamp11127 Super Moderator Staff Member

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    The old days of flame hardening has been replaced in some areas with induction hardening. Unfortunately that only goes a few thousandths deep into the metal. If the scratch has breached the hardend layer the cam will slowly grenade.
     
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