cam tower

[solvent joe]

I just started looking into my other motor to get an idea on what kind of shape it was in to see what surprises in might be hidding for me when I rebuild it . The first thing I discovered was when I removed the oil pan I found the broken off end of a scew driver and a spring. So I figurede I better dig a little deeper . I pulled of the timming chane cover and discovered that the tensioner was destroyed, the screwdriver !. Then when I tried to slide the cam out it wouldnt come out, so I unbolted the cam towers the all slid off easily except the center one it spins but will not slide off the cam. This is the reason for my post , shouldnt it slide rite off? If I have to replace it will I need to replace all five ? Where could I find new cam towers? any help would sure be appreciated.

[Nissanman]

Nissan, in their FSMs, are very strong in their wording re cam tower removal.

Essentially they advise line boring the towers if they are ever disturbed.

However, in the real world where heads are welded, machined, ported, heated, pressure tested and whatever, the towers are usually the first thing to be removed.

The thing to do when re fitting them is to : -

1 put them back in the same order they were originally,

2 use head saver shims if the head thickness has been reduced too much by re-facing,

3 tighten them gradually whilst at the same time spinning the cam that will be in the engine when it is assembled.

The last point is certainly not line boring but it will ensure that the towers will be suitably aligned for the relevant cam shaft.

If the towers are torqued to the recommended value and the cam still spins when whizzed by hand, what more can you do??

As for the recalcitrant tower, I don't think there is any set screw or other reason why it shouldn't just slide off.

Try moving it to both the front and rear, there might be a burr on the tower preventing it from moving one direction or another.

Worst case, leave it on the cam and re-mount it to the head when required!

The tip of a screw driver:ermm::ermm:

Methinks there was an [vain] attempt, by the dreaded Previous Owner, to lever the cam chain tensioner back together:finger::finger:

[Z train]

Taking the above advice one step further,measure everything to ensure the cam sits where it "should" in relation to the head surface.Too many shops/POs will cut the head and NOT raise the cam towers back to the proper specs.This MIGHT be part of the reson for the tensioner issue.

[solvent joe]

thanks for the help guys . I will try again to remove the cam tower, I do not plan on reuseing any of the valvetrain components so I need to get the tower free from the old cam. So if I damage the tower I will need to replace it ,so back to the second part of my question. do you think I would need to replace all five. This is the N42 head will I need to get them from another N42 or will other castings work N47 etc.

[JimmyZ]

It would be easier to use another set of towers. It really depends on whether the factory did the final machining as an align bore. (Towers in head) If this were the case then you'd have to use a matched set. As a couple thousandths/in difference is to be found between heads.

If the factory used a jig to hold all towers in close proximity for boring then all towers should in theory be the same. (Towers machined outside head)

Heads are pretty cheap to come by and you will probably end up with a few spares in the end.

2c

Jim

[solvent joe]

This thing is really stuck and I can not get it off the cam , so I will be looking for another N42 head or a set of cam towers. If anyone has a head or good cam towers let me know Thanks for the replies to my questions