F250 / 5.4 motor has a bottom end knock

mach · 05-01-2006, 10:29 AM

Hey Guys,

I just purchased a 1999 F250 x-tra cab 4x4. i love the truck, but the engine has a bad knock in the bottom end. It does run, but the knock doesn't go away. I've been told that several of these 5.4 mod engines have this same problem. I assume its a bearing or rod problem. I've been told that I may be able to pull the plug wire to locate the cylinder, then pull the pan and change the bearing / rod for that cylinder. Does that sound right? The truck has 110,000 miles on it. I got a price from Jasper engines for a new longblock for $3500, but I don't really have that much I can spend. I don't know too much about internal engine "stuff" so I would appreciate any help youguys can offer.

Thanks everyone,
Mach

390FE · 05-01-2006, 01:35 PM

do you know what oil was used in the motor? I have heard of guys using 10W 40 and 20W50 and all the heavy oils used in older motors. The new Mod motord 4.6L & 5.4L require 5w30(20). There is an issue with oil starviation when using heavier weight oils.

If your trying to save a few buck and do it yourself I would try to put the truck up for a day or so. I would pull and mark all the main and rod bearings. Where you don't know much about motor internals I would than take the bearings to a reputable machine or motor shop and ask them to look at the bearings to tell you what is wrong. Tell them you have a low end knock and these are the bearings. They should be able to look at the bearings and be able to tell you a lot about whats going on with the lower end. They might even be adle to tell you what cylinder is causing the knock(hence why you need to carefully mark what bearings went to what cylinder). They may even be able to tell you of more motor work needs to be done of it just replacing a bearing would fix the problem. I put parts into individual bags and mark the bags.
At 110K you might be able to get away with just repalcing the bearings. I would replace all of them at the same time but thats just me.

Try to take pictures of the lower end parts without the bearings in it if possible. To show to the machine shop so they can see the condition of the metal that contacts the bearings.

mudseeker · 05-03-2006, 04:33 AM

take it to a shop and have it checked out. it's a pain to work on the lower end with out pulling the motor, especialy if you end up changeing out rods. you have to pull the heads to do that.

EVIL-E · 01-21-2007, 03:24 AM

this might help..i had the same probelm with my motor it has well over 100k..my dad's an motor rebuilder...we droped the oil pan & replaced all the ( connecting rod bearings ) which wear out way more than main bearings.....& we also replaced the oil pump.. we decied to leave the old main bearings cause of the timming chain and all...it runs and sounds like a champ now....i hope i was helpfull

1saxman · 01-22-2007, 06:29 PM

Generally speaking, if it's a loud 'clack' it's a rod bearing. If it's a deeper 'knock' it's a main. This isn't cast in stone, just a hint. The engine won't run for long with a bad rod bearing, but sometimes they do with a main knock. Either way, you may as well figure on putting an engine in it before long. As soon as you fix the bottom end, something else is going to blow.

theman69 · 10-16-2008, 11:14 PM

i have the same dam knock on the bottem of the motor and i was wondering how many hours would it take to take out the main and rod bearings and how could you find out what cylinder is doing it. mine is a 03 f150 x cab 5.4 L i tryed crank case **** and it made it a little quieter and how it is getting louder and it is getting colder. i realy dont want to buy a new motor

any idea any one

05-01-2006, 10:29 AM	#1
mach Junior Member Join Date: May 2006 Posts: 7	F250 / 5.4 motor has a bottom end knock Hey Guys, I just purchased a 1999 F250 x-tra cab 4x4. i love the truck, but the engine has a bad knock in the bottom end. It does run, but the knock doesn't go away. I've been told that several of these 5.4 mod engines have this same problem. I assume its a bearing or rod problem. I've been told that I may be able to pull the plug wire to locate the cylinder, then pull the pan and change the bearing / rod for that cylinder. Does that sound right? The truck has 110,000 miles on it. I got a price from Jasper engines for a new longblock for $3500, but I don't really have that much I can spend. I don't know too much about internal engine "stuff" so I would appreciate any help youguys can offer. Thanks everyone, Mach

05-01-2006, 01:35 PM	#2
390FE Senior Member Join Date: Sep 2005 Location: S. NH Posts: 336	do you know what oil was used in the motor? I have heard of guys using 10W 40 and 20W50 and all the heavy oils used in older motors. The new Mod motord 4.6L & 5.4L require 5w30(20). There is an issue with oil starviation when using heavier weight oils. If your trying to save a few buck and do it yourself I would try to put the truck up for a day or so. I would pull and mark all the main and rod bearings. Where you don't know much about motor internals I would than take the bearings to a reputable machine or motor shop and ask them to look at the bearings to tell you what is wrong. Tell them you have a low end knock and these are the bearings. They should be able to look at the bearings and be able to tell you a lot about whats going on with the lower end. They might even be adle to tell you what cylinder is causing the knock(hence why you need to carefully mark what bearings went to what cylinder). They may even be able to tell you of more motor work needs to be done of it just replacing a bearing would fix the problem. I put parts into individual bags and mark the bags. At 110K you might be able to get away with just repalcing the bearings. I would replace all of them at the same time but thats just me. Try to take pictures of the lower end parts without the bearings in it if possible. To show to the machine shop so they can see the condition of the metal that contacts the bearings. __________________ 87 Toyota 4x4 -- 72 F250 -- 68 F250 -- A Ford kah -- New to Family is 07 Ranger FX4

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05-03-2006, 04:33 AM	#3
mudseeker Senior Moderator Join Date: Feb 2006 Location: michigan Posts: 7,155	take it to a shop and have it checked out. it's a pain to work on the lower end with out pulling the motor, especialy if you end up changeing out rods. you have to pull the heads to do that.

01-21-2007, 03:24 AM	#4
EVIL-E Junior Member Join Date: Jan 2007 Posts: 5	this might help..i had the same probelm with my motor it has well over 100k..my dad's an motor rebuilder...we droped the oil pan & replaced all the ( connecting rod bearings ) which wear out way more than main bearings.....& we also replaced the oil pump.. we decied to leave the old main bearings cause of the timming chain and all...it runs and sounds like a champ now....i hope i was helpfull

01-22-2007, 06:29 PM	#5
1saxman Full Member Join Date: Jan 2007 Posts: 32	Generally speaking, if it's a loud 'clack' it's a rod bearing. If it's a deeper 'knock' it's a main. This isn't cast in stone, just a hint. The engine won't run for long with a bad rod bearing, but sometimes they do with a main knock. Either way, you may as well figure on putting an engine in it before long. As soon as you fix the bottom end, something else is going to blow.

10-16-2008, 11:14 PM	#6
theman69 Junior Member Join Date: Oct 2008 Posts: 1	i have the same dam knock on the bottem of the motor and i was wondering how many hours would it take to take out the main and rod bearings and how could you find out what cylinder is doing it. mine is a 03 f150 x cab 5.4 L i tryed crank case **** and it made it a little quieter and how it is getting louder and it is getting colder. i realy dont want to buy a new motor any idea any one