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Old 07-18-2011, 09:37 PM   #1
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Default 2 spun rod bearings, what to do?

i bought a 2000 f150 4x4 ext cab with the 5.4 cheap a couple of weeks ago... it has an engine knock... i dropped the pan this evening to find that the two rear rods had spun bearings(dont know the cylinder numbers, next to flywheel)... there was no evidence of ring blow by...

so, to get to my question... should i try to rebuild the lower end of this engine or replace it with a salvage engine... i found an engine locally for 1300 with 80k on it...

any advice will be great
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Old 07-18-2011, 10:03 PM   #2
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Numbers 4 and 8 are always the first to go because with low oil pressure they're starved first and the longest. I would turn the motor until you can remove the caps and check out the journal on the crank. If it's not scarred up you can push up the piston a little and replace those two rod bearings all with the motor in the vehicle and keep on truckin.
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Old 07-19-2011, 06:08 PM   #3
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Speaking old school, spun bearings = rod replacement as well as crankshaft. This being a 5.4 with new fangled snap cap rods, or what ever they are called, I think more research is in order. Where is torkum when we need him?
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Old 07-19-2011, 08:46 PM   #4
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the rod the second from the back (i am guessing #4) has noticeable damage from the bearing failure... i have removed the caps and found that the journal is chewed up.. the bearings are blue in the middle from heat...

is the oil gauge in the truck an actual gauge or just a replacement for a dummy light?
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Old 07-19-2011, 09:40 PM   #5
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It's just a switch that shows pressure at a certain PSI. Old Bill is right 99% of the time but on occasion you if you catch it quick enough the journal and rods will be fine. This is not one of those occasions.

If you want to replace two rods make damn sure you get them from Ford. Mixing OEM and aftermarket engine internals is bad because aftermarket parts are almost always lighter. If you want to replace them all, which wouldn't be a completely awful idea aftermarket sets are fine. You can have the crank turned and just get oversize bearings and generally save some money.

Very important note is the 4.6 has 3 different size crankshafts so I'm guessing the 5.4 does as well so I'd advise you to take the entire block to a machine shop so they can match the bearings to the block and crank.

The motor I put in my truck I bought blown from a mustang, 7 and 8 spun and got the crank turned and oversize bearings and replaced both rods and one of the pistons so you're going to want to look your pistons over as well. Any scratches on the piston skirt is no good. You should probably re-ring at this point as well.

Basically you will spend probably close to the $1300 you would on a used motor but have a reconditioned one. That's the option I would take but my truck isn't a DD. If you need it in a timely manor you can put the junk yard motor in in a weekend instead.
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Old 07-20-2011, 08:43 PM   #6
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thanks for your info... mine isnt a daily driver either, i may do the rebuild... any tips on a good tare down manual?
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Old 07-20-2011, 09:01 PM   #7
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I used the Ford shop manual because I'm a Ford tech lol but I'm sure a Haynes or Chilton will be just fine. One thing you've got to know is that you need a special set of tools to time these modulars and it's like a $400 kit. There is a lot of expense in it if you're not set up to rebuild a motor, engine stand, timing tools, torque wrench and all of that. It kind of slipped my mind because I had all that at my disposal, you'll have to seriously consider your ability to rebuild the motor, there's a lot to check, cylinder roundness and wear and head straightness and the deck for being warped all of which requires special tools, or a trip to the machine shop. I'd recommend you go to a machine shop and talk to them about it before you decide anything.
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Old 07-21-2011, 10:19 PM   #8
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i havent been into an engine since i was 17, but i am a commercial HVAC tech... i have rebuilt several compressors (air and refrigerant) over the years so i am confident about tackling the lower end... just need info to do the rest...

what kind of speciality tools are involved?
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Old 07-22-2011, 08:12 AM   #9
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The most expensive things are the timing tool set ($400) and torque wrench ($150+) and you need an engine crane and engine stand plus you need to have all the tools to pull the motor. Unless you get a whole new set of rods and pistons already attached they need to go in a 1100 degree oven thing to expand the end of the rod so you can get the piston pin started and then they need to be pressed in from there. That's most of it I think. I guess you probably need a fan clutch tool if you don't have one. You definitely need plastigage to use to make sure the bearings are laying right when they're torqued down.
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Old 07-22-2011, 08:41 PM   #10
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thanks for the info... i checked the crank again, it wasnt as bad as i first thought... i picked up a couple rod bearings today and gonna install them tonight.. i will keep you posted
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