1st Gen R53 Cooper S Most liked posts in thread: What they DONT tell YA!! Issues....

.......but the engine blew. Not acceptable.

PS: Who's car was it that made 397 on an OEM head and what all else had been done to it? Details please?

 

Then why use it as an example?

How quick did this one blow?

 

A shroud on the oil pump cover prevents the timing chain from dropping far enough to skip from one tooth to another.



It cups the chain within a couple mm of the crankshaft sprocket.



When replacing a camshaft there is no need to remove the chain from the camshaft sprocket; just move the sprocket with the chain wrapped around it to the left after removing the camshaft bolt.

When removing the head, it is necessary to pull the chain guides out and lower the chain. As long as the chain has been marked to index corresponding teeth on the sprocket, there is no risk of losing original valve timing. I can see where the chain & sprocket could be muscled on the camshaft thereby moving the crankshaft or other installation errors, but not from losing the chain's position on the crankshaft sprocket.

 

Thanks for pointing out a gotcha... Best to learn these things before they bite you.

 

A good friend doing a headgasket had his timing chain skip a tooth or two when it sunk down far enough.

 

I guess i dont understand the point of this thread.
The chain will not skip unless you rotate the motor, that is explained in the directions quite clearly.
If your skipping the timing chain as they say

 

Which "directions" are you speaking of ?

Pretty sure Thumper has done more head swaps on the MINIs then almost anyone. Well, i would say he is in the top five atleast lol.

 

Oh sorry, the directions as outlined in the Bentley manual.

 

There is nothing wrong with taking extra precautions when performing critical procedures like changing a camshaft or replacing a head. I take extra steps that may be considered overly cautious, or unnecessary, when I do just about anything on a MINI. The OP had it right when he cautioned against rotating the crankshaft with the chain removed from the camshaft sprocket; assigning blame to lowering the chain, is misguided.

Unloading tension on the cam chain, removing the guide and tensioner, taking the chain from the camshaft sprocket, and lowering the chain, are unnecessary steps for replacing a camshaft. The only reason I can see this procedure is described the way it is in the Bentley, is because it is in the same section as cylinder head removal. The step of removing the guide and tensioner are omitted in the Bentley directions, but the chain won't release from the camshaft sprocket easily with those parts in the way. I view these two examples as technical editing oversights, something more benign than a faulty procedure, which would lead you dangerously astray.

I have a more streamlined approach to changing the camshaft that avoids removing the timing chain. I devote one whole sentence to keeping the chain on the camshaft sprocket and moving to the side. http://www.werkinmini.com/R50-R53%20Camshaft%20Installation.pdf

If the timing chain moves one tooth on the crankshaft sprocket, and the chain is returned to its original location on the camshaft sprocket, moving the chain one tooth on the camshaft sprocket to compensate, will be an over-correction. Breaking down the original story that led to this thread, the car in question entered the shop running, there is also an insinuation it had been on the dyno, because there is a report of a 15hp loss of power. What occurred at the "other" shop other than a head swap is unknown.

Please supply more information other than a vague anecdotal comment.

Paperback Bentley Manual 2002-2004 pages 113-36 and 116-9, Hardbound 2002-2006 pages 113-35 and 116-9. I have removed the timing chain cover and measured the clearance, and can verify there is not enough to allow the chain to drop away from the crankshaft sprocket; no technical editing oversight in this case. I don't even see how the chain could walk unless the crankshaft rotated quite a bit.