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'95 993 / 2011 F150 Raptor SC / Land Cruiser D4D V8 / 500 SEC
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Discussion Starter #1
So I've got this question.

I've been looking at several threads on how to acomplish things.

The 'easy way' if you have a workshop and all the tools is extract the lump. I'd like to avoid this due to a temporary lack of space in the shed.

So all thes threads seem to revolve around an elaborate scheme with clamps, tie-wraps or grip pliers to secure the chain to the cam cogs, splitting the old chain, attaching it to the new one and then slowly and painstakingly threading the new chain around untill it emerges from the opposite side you started from.

Why is this ?

My MO would be : set everything to it's respective check marks, split the chain, thread it through with the old chain on just the crank, check the cams and crank positions and then reattach it without using the elaborate tooth-by-tooth approach.

So why was this inch-by-inch approach concoted ? What am I missing ?

Thanks,

Pete
 

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Moderator
1991 500SEC 55K mi. 1987 560SEC Now 153K mi. 2020
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4,526 Posts
Hi there Pete,

" ...split the chain, thread it through with the old chain on just the crank... "

If that were possible I am sure that would be the conventional method, however on our cars the valves hit the pistons if the valve timing is not correct... Interference Engines sustain much damage when this occurs.

The inch by inch method ensures this correct valve to piston relationship known as " Valve Timing ".

I hope this sheds light..

Cheers Good Luck, MBL
 

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1983 380SL, 2000 S430, 1991 420SEL (retired) - RHD
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5,526 Posts
Loading timing chain

If you're not really careful you can drop the chain and jam it like I did.The "tooth by tooth" description is really a bit of an exageration- it's more like 45 degrees at a time. You have to disconnect/ connect the new chain and, using the crank, advance it and maintain constant pressure so as not to drop the chain off any teeth on the sprocket, changing the timing position. Cable ties or visegrips are commonly used to hold the chain in position on the sprocket, hence the slow progress- turn, release cable (or visegrip), tie new one (or move visegrip), turn and so on. Use of a chain loader obviates this as it will not allow the chain to release from the sprocket as you rotate the crank.
If you get the sprockets disengaged from the correct link it is a risky business rotating the cams unless you remove the lifters. Again, been there, done that.Care pays dividends here.
Good luck
BTW if you remove the tensioner first- it's a lot easier to work with (but also easier to drop).
 

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'95 993 / 2011 F150 Raptor SC / Land Cruiser D4D V8 / 500 SEC
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Discussion Starter #4 (Edited)
Hi there Pete,

" ...split the chain, thread it through with the old chain on just the crank... "

If that were possible I am sure that would be the conventional method, however on our cars the valves hit the pistons if the valve timing is not correct...
It would not matter an iota. If you take the chain tension off the cam sprockets they will all default (possibly with a little help) to the 'closed' position. I.e. as long as you put them back on the marks before reconnecting the chains all will be well.
 

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1989 560SEC, 1989 560SEL, 1995 E420
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Peter,

Just make sure you've removed all the rockers first. Otherwise you may not be able to rotate the cams to where you want.

Mike
 
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