F-150 knock and missfire on #6...

[Ben_Dyer]

ok so my fiances truck developed a miss fire on #6. after calling the stealership and being todl that cylder #6 is the third one back on passnger side (V8 triton), i replaced the plug, coil pack, and injector. to no avail it was still stuttering and miss fireing. then after adding an injector cleaner the engine developed a nasty knock. to no avail i could not figure out what the knock was and decided it was a rod. with the engine donly having 80k on it i added an oil additive and drove it for about ten miles and with no improvement in the knock or anything i parked it.

Being im in a podunk little town and dont trust the local mechanics i took it to the stealership. informed them of the work I did and what cylider i did it too (pointed it out) as well as what the diagnostic was saying about the misfire. they said ok and said they would look into it.

hour later i get a call saying that #6 is the third back on the driver side

. and they swapped all the new parts over to the correct cylinder and tryed to start it and nothing! just clicking from the starter. go down there and they say the engine is siezed. when they tryed to start it it must have broke a rod. So told them to tear down to the valve covers and see if a rod had broke, as i was fairly certain that it had.

today i get a call that indeed it had broke a rod and that i needed a new short block (that being new rods, pistons, crank, and block). this sounds way fishy to me

. can someone elaborate on how a broken rod would equal that kind of damage. i am going to go down there and have them explain it to me but would like some outside info before i do.

 

[whitexj98]

Well the rod probably jamed itself into the side of the block ruining it.

 

[trippled]

x2. you didnt say what year it was but im assuming its a 5.4L? if youre buying it from ford you might be better off buying the longblock reman from ford. should have 3yr 100k mile warranty and youd be looking at less labor to do a short block.

now when an engine throws a rod, theres quite a bit of rotating force that usually hits the fallen rod. usually this bends it, smashes it into the block and causes all kinds of damage to the block rod and crank. i would ask tho how they came up with the rod if they only took off the valve covers and ask if they can show you the damage. 5.4 are notorious for crappy valvetrain but i havent seen one throw a rod yet, but not impossible.

 

[kastein]

x2 on what whitexj98 said, I've seen motors with a busted rod end up with a 2" hole through the side of the block, piston shattered and massive scoring / chunks taken out of the cylinder walls, crank bent/wrecked from the rod flapping around, huge hole in the oil pan, all the bearings smoked from it running dry on oil. when you toss a rod the engine is basically done unless you get really lucky.

 

[jafoxj4.0]

i worked at the ford garage in my town for 13 yrs.the injectors are notoriuos for bleed off and trickling into the cylender if you go with the long block as previously stated make sure you have the shop send the injectors out and have them flow tested it will let you know if their is a closing problem.they probably did a relative compression test with the diagnostic computer it is not a true compression test but it is a real time saver for the tech.if the injector bled into the cylender it is what probably what caused the bent rod do to it hydrolocking the motor.good luck