[CHADGOSS]

Here the deal had a motor rebuilt, was supposed to have a new cam and crank. Well he decided the old cam with 350k miles was still good, less than .001 of wear. He is telling me the cam is billet steel and the cam is usually not replaced in these motors. Is that true? Thanks for any input.

 

[Aljay]

The cams do wear but usually if the truck has been maintained(oil changed regular) the cam should be ok I have only seen one with a bad lobe. It was not kept up rest of motor was gabage also.

 

[CHADGOSS]

Even with 350k miles on the cam it should be ok. Anyone know what material the cam is made from forged steel or billet?

 

[Dr.Evil]

Forged or steel billet really doesn't make as much difference as the heat-treatment applied after the lobes are ground & polished. These engines have roller cam followers so there shouldn't be much if ANY wear on the lobes. There's no sliding friction...

 

[Roger Scraggs]

Oops! Camshaft [journals and lobes] are ground AFTER heat treatment. Do it the other way and you could end up with a nasty distortion.

Just being picky... but that's me! /ubbthreads/images/graemlins/wink.gif[Ex universal grinder/toolmaker]

Cheers! Roger S.

 

[Garbage_Mechanic]

In my experience with diesel engines with roller cam followers it is the roller bearing that is the fail point. The only cam I have lost in a similar motor as this was a 6.9, 290,000 miles, roller siezed, took out cam. Also another 7.3, same issue. If it were me I would replace the lifters. That is a lot of revolutions on those little wheels! There is not a cam/lifter worn in to each other/ don't swap or replace/ type situation on roller lifters since there is only rolling contact.

 

[danjreed]

[ QUOTE ]
Oops! Camshaft [journals and lobes] are ground AFTER heat treatment. Do it the other way and you could end up with a nasty distortion.

Just being picky... but that's me! /ubbthreads/images/graemlins/wink.gif[Ex universal grinder/toolmaker]

Cheers! Roger S.

[/ QUOTE ]

Well, sometimes there's a 'green' (preheat-treat) grind, and a hard grind on rotatives. I'd suspect this to be the case given the eccentric and non-uniform cross section nature of the cams.

I can't ever remember hearing of a roller cam failing, but if you're in there for a complete rebuild, it'd me worth it (at least to me) just for the security to replace the lifters. But that's just my $.02

Daniel

 

[CHADGOSS]

The lifters have all been replaced. The motor was supposed to have a new cam, but the builder decided not to put one in, not me. I found out after I got the truck back. Thanks for the reply's