Is this wear pattern caused by the valves not being adjusted enough? Causing the? Rotocap not to spin I replaced the Adjusting nuts that were bad but not the rotocap. This is a 1980 300sd picture of nut attached thanks.

OUCH.....
Did it harm the cam lobe surface ?

No it did not good god you get fast responce on this board!!!

On some subjects it is more like IM....LOL

Replace the rockers, too -- if the nut was worn improperly, so was the rocker lower surface.

Make sure you get the correct ones -- some nuts have chromed tops, and must be used with the correct rocker.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I did replace rockers on the four that were like this. The main reson I want too know about the cause is I have seen 2 low milage motors at picknpull $245 complete but both had several nuts that were worse than mine. I just wonder what I might be getting my self into if I bought one.

I would replace the rotocaps if the nuts were slotted or worn unevenly.

It can be hard to tell if the wear is uneven, though -- once the hardened material is worn off, the softer stuff underneath will wear much faster than the hard stuff left....

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I guess I am trying to understand how the valve train works to know why they would wear like this. Am I correct in assuming that the valve and therefore the nut rotate at sum rpm? I can not see how the nut would wear like these unless the valve wore too fail to rotate’ thus causing the uneven wear on the side of the nut. If and it is a big if I am correct. Would this not be indicative of damage to the valve or valve seat too? Can I use the nut, easy to see to tell if there’s potential valve or valve seat damage, cant tell without taking head off. Am I making any sense am I correct in my assumption of how it works. If not what is the rotocap’s function?

rotocap rotates the valve fractionally each cycle to keep it from wearing oval. Easy way to check is to check the valve clearance and then manually rotate the valve about 45 degrees. If the clearance changes, the valve and seat are worn out of round.

The nut, on the other hand, can wear funny even if it rotates. They are surface hardened and/or chrome plated, so if the plating goes or the hardening wears off, the wear will accelerater on the soft spot. This may in fact prevent the valve from turning.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Thanks now I understand and know how to check for hidden damage. You may well save me some bucks when I buy motor I really appreciate it
DHS