Hey guys, looking for some real-world advice from people who’ve actually dealt with this.
R53 with a Newman PH2 cam. Adrian did the tune — runs fantastic now that I found the reason for my misfire (Cylinder 4 wasn’t firing due to a bad coil pack).
The car has always had a tapping/ticking noise that never went away, so I pulled the valve cover, removed the rocker assemblies, and checked the lifters.
Here’s where the problem hit:


When I removed the cam caps, several cracked.


I torqued them previously to 22 ft-lbs in the correct sequence, so I don’t believe this was an over-torque failure.


Picked up a full set of caps from a junkyard R53 head.


Now the conflicting info begins:


Majority of Facebook comments say cam caps can’t be swapped because the caps are line-bored to their original head.


One person said the opposite — that I can install the junkyard caps, torque them down, and as long as the cam spins freely with no binding, it’s usable.


So before I replace the entire head or hunt for another one:
Has anyone here successfully run swapped cam caps on the W11?
If so, what measurements or checks did you do?
If not, is the “line-bored only with the original head” rule absolute on these motors?
Appreciate any insight from people who’ve been deep inside these engines.

 

I did have the camshaft locking tool in place when I tightened the lifter assembly bolts. Is this the reason They might have cracked?

 

To me i would think it may be over torque but I am not a mechanic . Not sure how large of a torque wrench you used but from.previous experience i have learned that for low torque spec bolts it is a good.idea to.use a 1/4" or 3/8 torque wrench .

Did you use the cam caps in the same order and.orientation as you took them out? I do believe that they are machined with the head. Hopefully you also used assembly lube to help.with friction on the original startup.

Also a general observation but did you " gently ding:" the spark plug tubes where the lobe comes close when you spin the cam ? I remember having to do that when I installed my ph2 cam due to the tolerance being quite close . With expansion if the lobe starts to hit the plug tube I wonder if it would add stress to the cap .

Like I said i am.no mechanic and these are only suggestions so we may try to pinpoint what the issue was that caused it in the first place .

Also unfortunately feom what I have heard the head is machined with the caps togiether so I dont think a cap from a donor car would work .

 

Ngtphantom, thank you for your comments. I used a 3/8th inch torque wrench and asembly lube. Samer order for the cam caps as well. I didn't have to ding my sparkplug tube although I did know about the issue. They don't look to have come in contact with the cam at all. At this point I'm leaning towards a remanufactured cylinder head. I did notice that the exhaust lifters were easy to push down, however the intake ones are rock solid.

 

Sounds like u were on the corect path when u installed it .

On picture 2 of the camshaft it definetely looks like material was eaten away by being in contact with something , was that under one of the broken caps ?

 

They all looked good. The marks on the cam wiped off. I'll check again tomorrow in the day light. Just pulled the head. Looks like one of the cylinder 4 exhaust valves is partly gone. The bore and piston look okay.