1998 F150 locked up during starting, help!

My F150 is my once a month vehicle, and the other day when I tried to start it, it turned over about 3/4 then stopped cold, like something was blocking something. any advise what it could be? my friends and I
say that it is either something wedged in the starter area or possibly a stuck vavle wedged against a piston. snows pretty deep and I'd prefer to work on it when warm, so I don't have any rush to find out.
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On Mon, 8 Feb 2010 10:12:59 -0800 (PST), Tater

Pull the plugs an turn it over to find the one full of fuel or water and hope you did'nt bend a rod or crack a piston when it locked. This can on rare occasions be caused by a stuck valve but, I don't recall that being an interference engine offhand. It will be best to turn it by handwith the plugs already out . Fuel means a leaky injector - water is usually a head gasket. Water in the oil is also a bad sign.
Lugnut
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Tater wrote:

Question: What engine? V-6 or V-8
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You might have a 'compression lock' or a 'water lock' on the rotating mechanism of the pistons and crank shaft.
Crack a block and get water to seep into the piston, it fills the top as the values are closed on the compression stroke ... and the engine stops, sometimes it will even whine a bit before it stops ...
as you would whine as well if someone was kicking you in the ass to turn over and you couldn't.
Soooooo ... pull the truck into your gargage, thaw it out, pull the spark plugs, and see if you can crank it by hand in a backwards direction and then in a forwards direction until it stops again or not.
If it stops with the spark plugs pulled .. then a mechanical function is broken, a piece of metal is in there hindering the rotation the engine pistons and crank.
If it all moves, then put it together with the plugs back in, check for spark, add engine start to the fuel system, and give it a crank.
Not work again, then check for the compression, vapor, water lock stuff again. It is likely to be made known to you what it is at this time if you have not figured it out when you take it and thaw it out.
hope that helps ...
Alan
Tater wrote:

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On Mon, 08 Feb 2010 19:43:38 -0800, "Alan B. Mac Farlane"

He should not turn these engines backwards with the hydraulically tensioned timing chains. If the plugs are out, he should be able to turn it in it's normal rotation. It should also be turned at least 2 complete revolutions to make sure all cylinders have been fully cycled. He should see the suspect cylinder (not always) when the plugs are pulled. If there is a lot of fluid in a cylinder that is just beginning the compression stroke, it may lock before any liquid is pushed up to the plug. That is the reason for hand rotation in it's normal direction.
Lugnut

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ya lugnut .. this is sooo easy to Dx once the plugs are pulled.
he will see what the problem is real quick ...
if he has any eye for reading plugs.
This has been going down for some time and a hard freeze is what pulled it over just like taking a borderline battery down.
IMO and all that rot.
lugnut wrote:

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