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LeAnne
Lv 7
LeAnne asked in Cars & TransportationCar MakesFord · 1 decade ago

Is a '98 Ford Taurus 3.0L bent valve normal?

I have just finished tearing down the top end of a '98 Taurus for a misfire in cylinder 1.

Pre-checks showed there was no compression in this cylinder. All other cylinders were fine.

I found a bent exhaust valve and evidence that the exhaust valve had contacted the piston - (whether this was the cause or the effect of the bent valve I don't know).

I replaced the valve and dressed up the seat -

My question: Is this common or should I be looking for a cause before I put this beast back together?

Update:

It's the OHV 3.0L engine. (Pretty basic, cast iron engine.)

5 Answers

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  • FlagMichael
    Lv 7
    1 decade ago
    Favorite Answer

    Knowing your skill level, I am going to assume you have checked the obvious timing issues. The damage being confined to a single valve would have made me wonder anyway, not to mention that the engine was running okay on the other cylinders without having to reset the timing.

    I would look at the spring on that valve with a critical eye and I would probably replace the spring on suspicion. What we know is that the valve was in the way when the piston came up - maybe the spring was wimpy and made the valve float prematurely? It just doesn't make sense that one valve was being held open by the cam and then the timing went back to normal, so either the valve guide was grabbing the valve stem or the spring wasn't up to returning the valve in time. Or maybe some debris tried to fly through and got caught in the seat?

    I can't say I've heard of anything crashing one valve except for over-revving an engine ("sucking a valve").

    Source(s): 35 years maintaining my own cars
  • Uncle Red
    Lv 6
    1 decade ago

    I would check the top of the piston for a crack, This can be caused by the valve either floating or sticking open.

    When I say floating I mean the engine was at such high RPM's the valve can't shut before it reopens. so therefor the piston hits it and I would check all the piston tops for a mark in them the sticking valve would be something I might expect from an older engine. The valve was the cause the nick in the piston the effect.

    Sucking a valve is a term used when the valve stem stretches and breaks sucking the valve into the combustion chamber... Not a pretty picture

    Source(s): Seen it a few times in my line of work and it usually is the floating issue
  • gone
    Lv 4
    1 decade ago

    not normal, need to find out why.

    I would think something held the valve open, then hit the piston.

    stuck in the valve guide, but i guess it is good and loose as a used eng.

    maybe the lifter stuck and would not let the valve go down.

    or something that could stop the rocker arm.

    could the driver have over reved the eng and floated a valve ??

  • Anonymous
    1 decade ago

    Is this the DOHC 3.0? Or Vulcan?

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  • Frankie
    Lv 7
    1 decade ago

    It's possible in an interference engine. Did your timing belt slip or break? You probably should replace it while you're in there.

    Source(s): 35+ years fixing my own stuff
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