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  #1  
Old 06-25-2007, 02:01 PM
Brian Perkins
 
Join Date: Aug 2006
Location: Luanda, Angola
Posts: 135
Timing chain tensioner and rail replacement

In section 05-330 of the FSM (step 11), it says to remove the camshaft sprocket, but it doesn't say anything about removing the chain.

But... my question is this:
Is it possible to remove the sprocket without removing/unlinking the chain?

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  #2  
Old 06-25-2007, 02:56 PM
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Quote:
Originally Posted by PerkHouse View Post
But... my question is this:
Is it possible to remove the sprocket without removing/unlinking the chain?
Once you remove the tensioner, the chain has plenty of slack. Just remove the sprocket with the chain attached. Be careful of the thrust washer that lives behind the sprocket. It wants to take a fast trip to China if you're not careful........
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  #3  
Old 06-25-2007, 07:00 PM
Brian Perkins
 
Join Date: Aug 2006
Location: Luanda, Angola
Posts: 135
Thanks for the tip Brian!

Now, you're talking about the tensioner, spring, and "bolt" (aka thrust pin) - not the tensioner rail, right?

I'll strategically place a magnet back there to hold that thrust washer while I remove the sprocket, just to be safe! Oh, and maybe some vice-grips to hold the chain to the sprocket.?.

Thanks again!
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  #4  
Old 06-25-2007, 07:17 PM
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Quote:
Originally Posted by PerkHouse View Post
Thanks for the tip Brian!

Now, you're talking about the tensioner, spring, and "bolt" (aka thrust pin) - not the tensioner rail, right?

I'll strategically place a magnet back there to hold that thrust washer while I remove the sprocket, just to be safe! Oh, and maybe some vice-grips to hold the chain to the sprocket.?.

Thanks again!
Yep.

The problem is that the cam sprocket is the only thing that keeps the cam from moving rearward. So, once you pull the sprocket, next thing you know, the camshaft slides rearward and the washer falls off. The washer can't fall off the front of the camshaft unless the camshaft moves rearward. So, the safest bet is to put a block of wood or some device at the back end of the cam so it cannot move rearward. Then, you can't lose the thrust washer.

Do yourself a favor and paint a large white mark across the face of the chain and onto the sprocket. You'll be overjoyed that you did this upon reassembly. Trust me.
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  #5  
Old 06-25-2007, 07:41 PM
Brian Perkins
 
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Quote:
Originally Posted by Brian Carlton View Post
Do yourself a favor and paint a large white mark across the face of the chain and onto the sprocket. You'll be overjoyed that you did this upon reassembly. Trust me.
OK... it shows that in the manual. I had no idea why, but I had planned to do it anyway.
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  #6  
Old 06-25-2007, 08:02 PM
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You can use plastic zip ties to hold the chain on the sprocket.

Which rail are you replacing?

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  #7  
Old 06-25-2007, 08:05 PM
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Originally Posted by sixto View Post
You can use plastic zip ties to hold the chain on the sprocket.
With the painted white line, you can just remove the sprocket from the chain, if desired.
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  #8  
Old 06-25-2007, 08:07 PM
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Certainly wouldn't skip the mark. I just find zip ties less cumbersome than vice grips. Can't accidentally knock loose a zip tie either

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  #9  
Old 06-25-2007, 08:10 PM
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Originally Posted by sixto View Post
Certainly wouldn't skip the mark. I just find zip ties less cumbersome than vice grips. Can't accidentally knock loose a zip tie either
Personally, I don't see the need for vice grips or zip ties. Just remove the sprocket and reinstall it in the same position with respect to the chain.

The only reason to use the zip ties and/or vice grips is when you're rolling in a new chain and you lose the reference mark........naturally.
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  #10  
Old 06-25-2007, 08:51 PM
Brian Perkins
 
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Sixto, I'm replacing the tensioner rail; that's why the cam sprocket must come off.

Brian, I will be replacing the chain soon too (probably late July), but the tensioner pin and tensioner rail need immediate attention. (I wish I would've taken a picture while I was doing the valve adjustments.)
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  #11  
Old 06-25-2007, 08:54 PM
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Tensioner rail? The front cover has to come off for that (pull radiator, remove fan, remove crank pulley installed to 250 lbft, etc.).

Maybe you mean the upper guide rail?

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  #12  
Old 06-25-2007, 08:56 PM
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Oops, I see 82 300SD in your sig line. I thought this was a 603. Sorry about that.

Sixto
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  #13  
Old 06-25-2007, 11:18 PM
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Quote:
Originally Posted by PerkHouse View Post
Sixto, I'm replacing the tensioner rail; that's why the cam sprocket must come off.

Brian, I will be replacing the chain soon too (probably late July), but the tensioner pin and tensioner rail need immediate attention. (I wish I would've taken a picture while I was doing the valve adjustments.)
Are you sure the tensioning rail needs to be replaced? The surface of that rail is made out of unobtainium and it's almost impossible to wear through it to the steel backing material.

My 617 had a groove in the rail that was maybe 1/3 of the total depth of the material. I'm sure the rail is good for 400K miles.

Before you do all that work, take a couple of closeup photos and post them so we can comment.
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  #14  
Old 06-26-2007, 08:00 AM
Brian Perkins
 
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Quote:
Originally Posted by Brian Carlton View Post
Are you sure the tensioning rail needs to be replaced?
Yes, I'm certain, but not because of the "unobtainium" surface. It's fine.

It's the back side that's the problem - the protrusion which makes contact with the pressure bolt (aka thrust pin). They are misaligned causing significant wear to both the "bolt" end and the contact point. It looks like the rail might slip off toward the rear of the engine any moment, causing the chain to lose its tension and ... well, use your imagination.
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  #15  
Old 06-29-2007, 11:12 PM
Brian Perkins
 
Join Date: Aug 2006
Location: Luanda, Angola
Posts: 135
an idea for pin removal tool

What if I just used a bolt, nut, washer and a small piece of pipe?

=[ <\\\\\[=====]|[]\\\\\[]

=[ pin in engine
<\\\\\ bolt (6 or 8mm - FSM says two pins need to be removed)
[=====] pipe
| washer
[] nut
\\\\\[] bolt head

1. thread nut all the way onto bolt
2. slip washer onto bolt
3. slip pipe on bolt
4. thread bolt into pin head
5. tighten nut while holding bolt head, causing pin to be pulled from engine


(I realize pipe ID must be large enough for pin head.)

Do you think it will work?

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