How to replace a chain? - Makita UC4030A 16" Electric Chain Saw

pull the chain clutch back towards the handle
it is not a chain lock but a clutch release that stops the chain from turning
pulling it back engages the clutch to drive it

replacing timing chain???...Costs??? - Ford Explorer

www.explorerforum.com > ... > Stock 2002 - 2005 Explorers

Mar 20, 2008 - 8 posts - ‎5 authors
Stock 2002 - 2005 Explorers. ... What is the reccommneded time to replace the timing chain in a '02 Explorer 4.0 ... Costs inc. mechanics labor? Timing chain replacement cost on 2003 Ford Explorer ...
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Sounds like the chain is worn out and needs replacing if there is no more adjustment!

A good idea is to replace the sprockets at the same time, as they wear along with the chain, and will cause a new chain to wear out sooner.

May be its problem with timing chain and it has to be inspected and replaced.Or its possible that timing chain is got misaligned.

There are few help,links provided related to timing chain assembly and dis-assembly. Go through it and confirm proper inspecting of timing chain.

Click the required help link below:----How to Replace Timing Chain Cover & Seal on Audi A4 ? http://repairhelpcenter.blogspot.com/2011/11/how-to-replace-timing-chain-cover-seal.html
----------1982 Toyota Pickup: Set ignition timing, engine overheating, timing chain issue, dist off? http://whatisbyme.blogspot.in/2012/05/1982-toyota-pickup-set-ignition.html
----------How to Remove Timing Chain Cover and Seal on Toyota Previa?

http://technoanswers.blogspot.com/2011/12/how-to-remove-timing-chain-cover-and.html

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How to Remove Timing Chain and Gears on Toyota Previa?

http://technoanswers.blogspot.com/2011/12/how-to-remove-timing-chain-and-gears-on.html

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Ford Mondeo ST220 camshaft Timing specifications? http://technoanswers.blogspot.in/2012/02/ford-mondeo-st220-camshaft-timing.html
------------Replacing Timing Chain Cover For 2009 Ford?

http://repairhelpcenter.blogspot.in/2012/03/replacing-timing-chain-cover-ford-2009.html

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Timing Chains & Front Cover Removal on 2008 Ford Taurus? http://repairhelpcenter.blogspot.in/2012/03/timing-chains-front-cover-removal-on.html
----------How to Replace Timing Chain Cover, Chain, Sprockets, & Seal On Ford Taurus? http://repairhelpcenter.blogspot.in/2012/03/how-to-replace-timing-chain-cover-chain.html
---------How to Replace Timing Chain & Sprockets on Ford Windstar? http://repairhelpcenter.blogspot.in/2012/03/how-to-replace-timing-chain-sprockets.html
---------Timing Chain & Sprockets Replacing on Ford, Mercury and Lincoln? http://fordrepairhelp.blogspot.in/2012/03/timing-chain-sprockets-replacing-on.html
----------How to Replace Timing Chain & Sprockets on Ford Edge and Lincoln MKX? http://howtobyme.blogspot.in/2012/03/how-to-replace-timing-chain-sprockets.html
------How To Replace Timing Chain, Sprockets & Front Cover on Ford Expedition and Lincoln Navigator? http://repairhelpcenter.blogspot.in/2012/03/how-to-replace-timing-chain-sprockets_356.html
---------Timing Chain, Sprockets, Front Cover & Seal removal for Ford Mustang? http://schematicsdiagram.blogspot.in/2012/03/timing-chain-sprockets-front-cover-seal.html
---------How to Replace Timing Chain on Buick LaCrosse? http://howtobyme.blogspot.in/2012/03/how-to-replace-timing-chain-on-buick.html
---------These details will help.For more help keep updated.Thanks.

If you replaced the bar AND the chain, you'll need to make sure the chain is the correct chain for the particular bar you've used. If you're only replacing the chain, you need to make sure the chain has the same # of drive links as your old chain (maybe one or two more, if you've had some removed because of chain stretch).

On that particular model, for a 20" chain, you could have a 78 OR 80 drive link chain (drive links being the part of the chain that rides in the groove of the bar). The correct drive link count is determined by the bar you've installed and should have been made clear by whoever you purchased the bar from. Some brands use an 80 drive link chain, but MOST use the 78 drive link chain.

If the bar you purchased uses the 78 drive link chain, but you have an 80 drive link chain, then no matter how far out you adjust the bar, you may not get the chain tight enough. PartsBuggy shows a listing of which bars use the 78 drive link chains here.

The timing chain keeps the major componants in the engine alligned. A new chain will allign the engine componants better than an old chain that is sagging... and will thusly make the engine perform better and get better fuel milage as well as last longer.

I would replace the chain and not even consider the tightening of a chain that is that worn out...

You are lucky not to have the chain skip and cause the valves to come into contact with the pistons... ( read ; Interference engine)

I am familiar with that vehicle but generally with timing chain replacement, the engine needs full access for pulley and cover removal and in some cases the cylinder head requires removal.
Generally timing chains last so that they only need replacement at engine overhaul and it is not an economic proposition to have to replace a chain unless some relative degree of engine work is also required at that time. 

Engine timing chains generally have a tensioner on them which maintains tension, but some chains can wear significantly and cause timing cover to be "ground away" because of "slop".

If the engine is making the noisy rattle of the timing chain against the cover etc, I would schedule a top overhaul (head, machine, test and valve grind) with the chain replacement dependent on mileage with the degree of action.

Some simple simplex timing chains (type of chain similar to motor bike chain) may be replaced without dismantling the engines but I would expect your chain would be a "duplex" dual sprocket type, these are most common. 
These chains are not generally expensive but replacing them can involve a fair amount of work. 

Good Luck and hope this helps, Others will have different ideas.

Timing chains do need to be replaced but they can typically go much longer between being serviced than can timing belts. The chain will stretch out over time and can 'jump' timing. If you have an interference engine then that can prove disastrous as the piston can crash into the valves.

Its not terribly common for a timing chain to jump timing but not impossible. I have a vehicle with nearly 120k with a timing chain and its never been replaced and is still in good shape, I have another vehicle with 170k also with a timing chain that has never been replaced.

If it were me and I was going to be doing some work in that area and had easy enough access to the timing chain, and the mileage was getting up there, I would replace it. Timing chains typically also have a tensioner, so if you replace it, dont forget this item.

The McCulloch ProMac 600 series (610/650) doesn't recommend a saw chain replacement part because you can get differently-sized bars for it. This one came with a 20" bar.
According to an Amazon.com search tonight, the Oregon company makes a replacement part stock number D70. I have got an Oregon H78 replacement chain at my hardware store and it's a hair too small. Not all 20" saw chains are created equal!!

If you have a chain, there is NO replacement interval. ALL 4 cylinder Highlanders have timing chains.