Camshaft bearings

[Morris_Gti]

just wondering how hard camshaft bearings are to change, fink the barings have colapsed in mine, its making loud squaling and rubbing noises fom underneath the rocker cover, next to the top cam pulley. im no mechanic so not really sure what the problem is. it was makng loud rubbing noises once i hit around +3000 revs for quite a while but it just went today after i started it up and im nt sure what it is?

[Rmachines]

hm you know if it is the journals there will be something more serious causing them to fail!  it could be allot more than a simple replacment,  if the bearings have gone, the camshaft journals will almost certainly be damaged so will need a new shaft and with that new followers to match the new surface.

Its very very rare for the camshaft to fail before anything at the bottom end, mainly becuase it runs at half the speed of the bottom end. 

Personaly i cant see it being the camshaft, but if it is, you almost certainly have blocked oilways or low oil/pressure

Unless of course the bottom end has been changed and the top left to do another 100K miles on top 

[saul79]

take the rocker cover off and check. oil pump would cause top end knock -low oil pressue

[Rmachines]

if it was knocking i could understand it, thats the lifters as said before, low oil pressure or just worn lifters/blocked oil ways can cause it.

What you describe does sound like rumbling journals?   Explain in further detail if you can.