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Posted by: larss Sep 24 2011, 10:49 AM

Took the cam sout of my spare engine and found this type of groove at top of both of the two middle lobes (not at the outer ones).The engine has some 150.000 km on it. The lifters looks wery fine.

Is this from wear or what ?
Should I dump this cam?

/Lars S

Posted by: Valy Sep 24 2011, 01:26 PM

That is excessive wear. See that recession in the middle of the lobe? The pressures on the lob concentrate in a point just below the lobe surface. That effect causes the lobe surface to collapse without any external signs of wear.
Newer cams have a black coating that helps lubrication.

I'm sure the lifters are done as well. Take 2 lifters, clean them and put them face to face and look against a light source. Their surface is round so they should touch like this )( and you should be able to see light between them. If they are worn out the surfaces will be || or worst () so you will see full contact between the surfaces.

Posted by: larss Sep 25 2011, 03:13 AM

Thanks!

The surfaces on the intake lifters are like () so those are bad to.

What is the most likely reason for this wear, bad oil, high milage or...?
Why did it happen only at the intake lobes/lifters and not at all at the exhaust ones?


/Lars S

Posted by: larss Sep 25 2011, 10:41 AM

What is the most likely reason for this wear, bad oil, high milage or...?
Why did it happen only at the intake lobes/lifters and not at all at the exhaust ones?

and also:

Is this a common and typical Type4 issue...?


/Lars S

Posted by: Dave_Darling Sep 25 2011, 11:23 AM

Tom Wilson's book tells us that this is the typical wear pattern. Not sure why it would only happen on the intakes.

--DD

Posted by: rdauenhauer Sep 25 2011, 11:24 AM

hi-mileage. actually pretty typical wear.