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RB25 Neo valve/lifter shim replacement in vehicle, without removing timing belt

CowsWithGuns

By CowsWithGuns,
in Tutorials / DIY / FAQ

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CowsWithGuns Enthusiast

CowsWithGuns

Posted
Posted (edited)

I was looking through old posts and got the impression that you have to remove the camshafts entirely (and hence the timing belt) to replace the shims. Can confirm this is not the case and I saved myself a mountain of f**king around.

If you need to measure your bucket shim diameters, you can unbolt the cams but keep them attached to the timing belt so they float up on an angle. You should have enough space to pull out three to four cylinders worth of shims (will have to rebolt cams and rotate to access the other cylinders) using a very strong magnet on a stick and a pick to keep the bucket depressed. Cylinder 1 is a bugger and needs some patience, massage, and masochism. They all sucked and my back hurts.

Remember that the very first camshaft retainer needs gasket schmoo on its tips (scrape and reapply), and follow the order of tightening and torque specs in the manual. Similarly, apply sense when unbolting the cams so they do not have excessive bending load applied along their length. Keeping the belt on makes this more difficult and I wouldn't be surprised if it's, strictly speaking, incorrect procedure. But it's an RB so - she'll be right ;)

I'm ordering my new shims from Precision Shims in melbourne per another forum members recommendation. Hopefully they aren't $30 each like you find on 'RB25 specific' shims lol!

 

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Edited by CowsWithGuns
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GTSBoy Grand Master

GTSBoy

Posted
Posted
20 minutes ago, Dose Pipe Sutututu said:

Great guide!

Yes, but....surely it is easier to just lift the cams? It's not as if it takes a degree in massage therapy to re-time the cams, especially if you put effort into constraining the belts so it stays put at the bottom.

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joshuaho96 Veteran

joshuaho96

Posted
Posted

Isn't the RB25 NEO a shim over bucket engine? In every shim over bucket engine I've seen you use a special service tool to depress the outer rim of the bucket and then use a magnet and a thin plastic spudger or something similar to pull the shims without undoing the cams precariously like you did. When I check the R34 service manual that's also what it depicts:

image.thumb.png.3342f14352651e75dedd0c5b19613aef.png

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GTSBoy Grand Master

GTSBoy

Posted
Posted

Yeah. Nissan manual for Nissan dealer workshops to minimise labour costs on services.

Mind you, they were planning for an evantuality that wasn't needed on about 99% of all Neo engines ever made. Like all Jap engines of the era, valve train components don't wear.

You can put a file on the cam lobe of a typical Toyota engine from the 80s and 90s and metal just melts away. Yet they never wear in service (provided they are, in fact, serviced!).

I still think it would be easier to just lift the bloody cams.

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CowsWithGuns Enthusiast

CowsWithGuns

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  • Author
Posted (edited)
1 hour ago, joshuaho96 said:

Isn't the RB25 NEO a shim over bucket engine? In every shim over bucket engine I've seen you use a special service tool to depress the outer rim of the bucket and then use a magnet and a thin plastic spudger or something similar to pull the shims without undoing the cams precariously like you did. When I check the R34 service manual that's also what it depicts:

image.thumb.png.3342f14352651e75dedd0c5b19613aef.png

Ah man this forum is something special. It never occured to me that I could depress the buckets with pliers a conveniently 30+ mm spaced tool. Will probably be heinous with stiffer valve springs but I'll fabricate something and try it out when my new shims arrive (I have reassembled the car).

Where do I get my hands on that document? I only have the short 'essential info' R34 manual that is in English - no pictures no joy.

1 hour ago, GTSBoy said:

Yes, but....surely it is easier to just lift the cams? It's not as if it takes a degree in massage therapy to re-time the cams, especially if you put effort into constraining the belts so it stays put at the bottom.

GTSBoy I was actually halfway through to lifting the cams until I realised I'll have to dump some coolant and pull my fan shroud at minimum to have any access to the tensioner. Also, I saw a risk that I don't restrain the timing belt to the lower sprocket correctly, which means the radiator and the harmonic balancer are coming out (or even worse - I don't realise it moves on the sprocket). Hell no, no thank you, god forbid, etc.

FYI, Precision Shims quoted me ~$12 per shim for 16 and $15 express shipping. Great price compared to the alternatives I saw.

Edited by CowsWithGuns
joshuaho96 Veteran

joshuaho96

Posted
Posted
24 minutes ago, CowsWithGuns said:

Ah man this forum is something special. It never occured to me that I could depress the buckets with pliers a conveniently 30+ mm spaced tool. Will probably be heinous with stiffer valve springs but I'll fabricate something and try it out when my new shims arrive (I have reassembled the car).

Where do I get my hands on that document? I only have the short 'essential info' R34 manual that is in English - no pictures no joy.

GTSBoy I was actually halfway through to lifting the cams until I realised I'll have to dump some coolant and pull my fan shroud at minimum to have any access to the tensioner. Also, I saw a risk that I don't restrain the timing belt to the lower sprocket correctly, which means the radiator and the harmonic balancer are coming out (or even worse - I don't realise it moves on the sprocket). Hell no, no thank you, god forbid, etc.

FYI, Precision Shims quoted me ~$12 per shim for 16 and $15 express shipping. Great price compared to the alternatives I saw.

https://www.ozwidetools.com.au/nissan-toyota-valve-lifter-bucket-shim-adjusting-t

Not sure if there's better options but this is what I found with a quick search. I found the full R34 service manual here: https://www.facebook.com/groups/gtrusa/files/

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CowsWithGuns Enthusiast

CowsWithGuns

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Posted
3 minutes ago, joshuaho96 said:

https://www.ozwidetools.com.au/nissan-toyota-valve-lifter-bucket-shim-adjusting-t

Not sure if there's better options but this is what I found with a quick search. I found the full R34 service manual here: https://www.facebook.com/groups/gtrusa/files/

Downloaded and bought. What a gamechanger, that is awesome!

CowsWithGuns Enthusiast

CowsWithGuns

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Posted

Following up, the special tool obliterates lifter buckets. I assume this happened because I have heavy duty valve springs. didn't realise how much damage it was doing because... I'm a total idiot. FWIW, I translated the japanese workshop manual page and followed the procedure as described. Also possible that this tool is different in shape to that recommended by Nissan, I had a very difficult time handling it compared to videos on youtube (on toyota engines using a similar tool).

Ironically, this forced me to remove the timing belt to pull out this fried bucket- the one thing I wanted to avoid - and it is serving to be as much of a pain in the ass as I expected. In conclusion, I recommend the method in the original post to handle this task.

Fortunately I was able to rescue the bucket with some very careful fine sandpaper 'machining' :)

380346619_1060669971578333_9030007012721792797_n.jpg

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joshuaho96 Veteran

joshuaho96

Posted
Posted
On 10/27/2023 at 7:11 AM, CowsWithGuns said:

Following up, the special tool obliterates lifter buckets. I assume this happened because I have heavy duty valve springs. didn't realise how much damage it was doing because... I'm a total idiot. FWIW, I translated the japanese workshop manual page and followed the procedure as described. Also possible that this tool is different in shape to that recommended by Nissan, I had a very difficult time handling it compared to videos on youtube (on toyota engines using a similar tool).

Ironically, this forced me to remove the timing belt to pull out this fried bucket- the one thing I wanted to avoid - and it is serving to be as much of a pain in the ass as I expected. In conclusion, I recommend the method in the original post to handle this task.

Fortunately I was able to rescue the bucket with some very careful fine sandpaper 'machining' :)

380346619_1060669971578333_9030007012721792797_n.jpg

That really sucks. I was a little unsure about the tool set but checking the actual tool listed in the manual it’s the same general idea:

image.thumb.jpeg.9b142840a9e0219fdf20315b618b5bee.jpeg

I suspect the valve springs are part of the problem but it seems kind of shocking that you could so easily mar the bucket with the pliers like that and also damage the edge. It’s not like dealer techs are particularly careful either. 

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