main engine bearings
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Elder User
Joined: Aug 2005
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main engine bearings
Some months ago when I replaced/inspected the engine bearings of my 91 4.0 with 180000 miles i was thoroughly impressed with the concept that properly sized engine bearings have absolutely no metal to metal contact in almost any operation.
While I only removed #3 main bearing, it was perfect, no visible wear, not even polishing the first of three layers of metal, the so-called tinning. it looked like it was instlalled 30 minutes of running time before I inspected it. Absolutely amazing. Oil truly does work as advertised. Even cheap oil.
The rod bearings were absolutely shot, worn into the third layer, into the steel backing. I believe this was because rod bearings are not well lubricated, only squirts when oil holes line up and that they are smaller and subject to centrifugal forces that mains are not.
It was an interesting experience, easier than changing spark plugs, simply an exercise. Pan removed easily after turning #1 counterweight to North position. Actually great fun. Project only took 3 hours of very reasonable work after raising the vehicle including appropriate imbibation of prescribed aero beer.
Engine still sounds like a box-of-rocks but I'm glad I did it. Still annoyed that oil pressure gauge is driven by a switch and could not be used for analysis.
I wonder if I did any actual good by changing the rod bearings.
Ken
While I only removed #3 main bearing, it was perfect, no visible wear, not even polishing the first of three layers of metal, the so-called tinning. it looked like it was instlalled 30 minutes of running time before I inspected it. Absolutely amazing. Oil truly does work as advertised. Even cheap oil.
The rod bearings were absolutely shot, worn into the third layer, into the steel backing. I believe this was because rod bearings are not well lubricated, only squirts when oil holes line up and that they are smaller and subject to centrifugal forces that mains are not.
It was an interesting experience, easier than changing spark plugs, simply an exercise. Pan removed easily after turning #1 counterweight to North position. Actually great fun. Project only took 3 hours of very reasonable work after raising the vehicle including appropriate imbibation of prescribed aero beer.
Engine still sounds like a box-of-rocks but I'm glad I did it. Still annoyed that oil pressure gauge is driven by a switch and could not be used for analysis.
I wonder if I did any actual good by changing the rod bearings.
Ken
Post Fiend
Joined: Apr 2005
Posts: 5,720
Likes: 5
From: Washington state
ken,
how is the timing chain in that 4L, betcha that is the noise u are hearing, Mr Slapply timing chain rattling around getting ready to turn into a ball of worthless steel. 180k is the max they last, had a small block Chebby that I got lazy with, 200k miles, the chain was so loose, I could jump gear teeth by hand, it started life as an upgrade double roller set.
these oversquare engines put less strain on the main bearings and even the rod bearings than the undersquare long stroke engines they are going to now to reduce quench chamber size. the Aero 4L piston has decent skirt length so reduces crank and rod loading. Ford does a good job of factory balancing the V6 family, the rods are selected and balanced to within a couple grams... just a good basic engine design, less than 30 hp per hole so light loading on reciprocating parts , tightening pollution regs killed it.
could you imagine NASCCAR or INDY ran under EPA vehicle polution regs, 100 mph top speed and takes half lap to reach 60 mph.
how is the timing chain in that 4L, betcha that is the noise u are hearing, Mr Slapply timing chain rattling around getting ready to turn into a ball of worthless steel. 180k is the max they last, had a small block Chebby that I got lazy with, 200k miles, the chain was so loose, I could jump gear teeth by hand, it started life as an upgrade double roller set.
these oversquare engines put less strain on the main bearings and even the rod bearings than the undersquare long stroke engines they are going to now to reduce quench chamber size. the Aero 4L piston has decent skirt length so reduces crank and rod loading. Ford does a good job of factory balancing the V6 family, the rods are selected and balanced to within a couple grams... just a good basic engine design, less than 30 hp per hole so light loading on reciprocating parts , tightening pollution regs killed it.
could you imagine NASCCAR or INDY ran under EPA vehicle polution regs, 100 mph top speed and takes half lap to reach 60 mph.
Last edited by 96_4wdr; Nov 18, 2005 at 09:28 PM.
