1999 F150 Won't Turn Over

I have a friend that has a 1999 F150 5.4 engine with 103K miles and it was running fine. They tried to start it and the starter will engage but not turn the engine over like it's seized. It's been jumped and it doesn't help. What could cause this? :runaround: :runaround:

Load test the battery first....then clean the terminals....sounds like you have decent voltage but not enough amperage....
Phillip

That's probably a firewall solenoid, eh. If so then also clean the two heavy-duty connections at the solenoid - one has a heavy wire running from battery positive terminal to solenoid, and the other has an equally heavy wire running from solenoid to starter.

Also take a look at the grounding strap which runs from the battery negative terminal to the engine block - that carries the return current from the starter so a good connection at both ends - battery and block - is vital for reliable starting.

See if you can turn the engine over by hand (put a socket on the crankshaft pulley's bolt and use a large ratchet), if you can turn it over by hand pull the starter and see if it will spin on its own with no load on it.

Thanks guys that's all good information...I'll pass it on to my friend in the morning.

My friend thinks it's something called hydra lock. When the engine was turned off one of the fuel injectors kept going and filled the cylinder with fuel and now the starter can't compress it....anybody heard of this and any ideas on how to fix besides replacing the injector?

Pull out all of your spark plugs and then try to start it, which ever cylinder is hydro-locked will spray what ever liquid is sitting on top of the piston out of the spark plug hole. This can happen with blown head gaskets and cracked cylinder walls as well, but instead of filling the cylinder up with gasoline it will fill it up with antifreeze. When you turn the engine over don't be anywhere near the spark plug holes whatever is in there is going to travel very quickly and go everywhere.

Leaking injectors cannot be repaired they have to be replaced.

One other thing to consider is that some of gasoline may have leaked past the piston rings and gone down into the oil pan, when this is all done and over with I would change your oil as well.

See if you can turn the engine over by hand (put a socket on the crankshaft pulley's bolt and use a large ratchet), if you can turn it over by hand pull the starter and see if it will spin on its own with no load on it.

Thank you Torch...there wasn't any gas in the cylinders so the owner tried what you said...and discovered that the AC compressor bearings were locked up solid and wouldn't let the engine turn over.

Glad to hear you figured it out, I would just leave the AC belt off for now if you can (as long as it doesn't run anything else (power steering, etc.)) until you can get the compressor replaced.

The engine has a serpentine belt and he tried to get a belt that left out the compressor but couldn't find one so he removed the compressor and installed a pulley in it's place...he'll deal with the compressor when he has time.