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s40rch

Camshaft lobes wearing round

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So on the weekend I was assisting with a cam belt change on an Alfa 156 2.0 JTS and the procedure starts by taking the cam cover off to lock the camshafts, however on doing so we found that the lobe of the second inlet cam of cylinder 1 had worn down to almost being round, the same with cylinder 3 exhaust valve. I've never seen anything like it, can anyone come up with an explanation for it? E.g collapsed lifter, bent valve, oil deprivation etc? It does miss on cylinder 1 when cold, after doing plugs and coils with no improvement this may explain some of it!
 
I think we will get some second hand cam shafts but should we be looking at lifters or complete overhaul of the cylinder head too? Wishing I took some pictures now!
 
I have read online that it could be fuel oil contamination due to a leaking injector (it's direct injection), sounds plausible!

Any advice would be appreciated.
 
 
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9 hours ago, s40rch said:

 

can anyone come up with an explanation for it?

 

because its an Alfa :whistling:

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Ah that'll be it!

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Insufficient oil film strength. This can be due to oil grade or infrequent oil changes. 

When changing a worn cam it's vital to also change its followers. 

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It runs 10w60 as specified in the handbook although we expect previous owners didn't, aftermarket camshafts are £350 each.  The current owner doesn't want to scrap the car and as we know second hand camshafts are hard to come by on their own, a complete engine would be easier.  I have a feeling that this old direct injection engine will cause nothing but problems!

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