Cam bearings

[Rawze]

(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.



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.