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+--- Thread: Cam bearings (/showthread.php?tid=688)
RE: Cam bearings - simon999 - 07-28-2016
(07-27-2016 )gatow900 Wrote: The reason I ask is because my cam are starting to wear and the engine only uses 1/2 gallon between oil changes 15 to 18 thousand milesHalf gallon oil consumption is acceptable. How did you find out that your cam bushings worn? Do they show any copper? Does your cam has dents , is it scored?
RE: Cam bearings - snailexpress - 07-28-2016
You can replace cam bearings yourself but you need to have skills and
1 Special tool it lloks like camshaft without lobes to center all bearings in line and press them in head
2 Special tools to remove old bearings
3 Labor is equal for bearings replacement or head
Any bearings misalignment could cause camshaft or engine destroy
would you try?
RE: Cam bearings - Rawze - 07-28-2016
(07-27-2016 )gatow900 Wrote: The reason I ask is because my cam are starting to wear and the engine only uses 1/2 gallon between oil changes 15 to 18 thousand miles
and...
(07-27-2016 )jimeneztrans84 Wrote: So you should replace your cam bearings and head if your burning 1/2 gallon of oil between oil changes?
Although valve guides can sometimes leak and/or go bad, overall engine oil consumption is generally associated with piston ring wear and has not much of anything to do with wear in the head. Just because a truck is not consuming much oil doers not mean there is nothing wrong. Most of the time, when the bearings in the head wear out to the point of needing replacing, the valve seats are worn out too,.. and this puts the engine at higher risk of it snapping a valve with no warning. I have seen this many times.
Here is some pics of a couple valves from within the same cylinder. One of them snapped off due to the head simply being worn out.
[attachment=1767] [attachment=1769]
BTW: that truck was not using any excess oil either.
BOTH those valves came from the same cylinder. If you compare the shiny area at the bottom of the 2 valves, you can see the one on the left was barely hanging on because the valve seat in the head was so worn out. On the one to the right, the valve seat was not nearly as badly worn.
With the valve seat in the head worn out,... the valve had nothing much left to hang onto to hold back all the pressure from combustion. It finally gave way due to the stress,.. and the broken pieces scored the cylinder badly, then causing a piston failure and other problems when it got jammed.
The sad part is that I warned this guy 2 weeks before it actually happened. I pointed this out when I did an overhead adjustment on his engine. Told him that his head was in dire need of replacing. -- I guess he didn't believe me?. who knows,.. but he put the truck back on the road and in less than 2 weeks the valves failed and snapped off. -- He ended up learning the hard way.
RE: Cam bearings - gatow900 - 07-28-2016
Thanks guys for the input guess I need to save a little more money to replace all. Better than buying a hole other engine.
RE: Cam bearings - jimeneztrans84 - 07-28-2016
Is there a way to prevent wear on cam bearings and cam lobes?
RE: Cam bearings - Vin - 07-28-2016
(07-28-2016 )jimeneztrans84 Wrote: Is there a way to prevent wear on cam bearings and cam lobes?
Yes, properly done Overhead Set adjustments every 200 - 250k miles will help.
Regular oil change interval based on your fuel consumption.
Bypass Oil filter if you have EGR putting soot back in the engine.
1/2 to 1 gallon of gear lube in the engine oil every oil change.
Increase oil pressure by shimming the oil pump pressure regulator.
RE: Cam bearings - Wiseman - 07-28-2016
(07-28-2016 )jimeneztrans84 Wrote: Is there a way to prevent wear on cam bearings and cam lobes?
Yes ! There's way to greatly reduce cam and bearings wear .
Shimming the oil pump , using a gallon of gear oil , use of bypass oil filter , correct tune , overhead every 200k and much more .
There's extensive threads about it in here . Read and educate yourself. The sooner the better.
Ha ... Vin beat me ...
RE: Cam bearings - jimeneztrans84 - 07-28-2016
Is there a way or anyone done a oil bypass filter for cm2250?
RE: Cam bearings - yamajason - 07-28-2016
(07-28-2016 )snailexpress Wrote: You can replace cam bearings yourself but you need to have skills and
1 Special tool it lloks like camshaft without lobes to center all bearings in line and press them in head
2 Special tools to remove old bearings
3 Labor is equal for bearings replacement or head
Any bearings misalignment could cause camshaft or engine destroy
would you try?
I went thru this same problem earlier this year and did not want to believe that I needed a new head and camshaft.
http://rawze.com/forums/showthread.php?tid=43
I believe I could have accomplished the cam bearing replacement, but what if I scratched the area under the bearing trying to remove it...oil would go thru that scratch under the cam bearing and my cam lobe would starve for oil again. With all the labor and downtime involved with pulling a cam, it wasn't worth it to me.
That was before I got got educated on the worn Valve Seat issue...
REPLACING THE HEAD is the cheapest and most reliable LONG-TERM SOLUTION.
The price of that is, well more than most of us have saved up and I really wanted to just drive and not spend any $ to save for it, but borrowing now to get it fixed ASAP makes the most sense. Except for my pride, I run a trucking business but I can't even afford to fix one lousy cam lobe or bearing problem.