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Old 27th November 2010
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Default 16v Timing Chain Replacement w/ photos

Hello Comrades,

To skip to the how-to part, scroll down past this paragraph

due to the fact that this job caused me an insane amount of anguish, I just have to share my misadventures with you so someone benefits from this. This shouldn't be a big deal but it is a job that you may have to perform on your Saab at some point. My car really needed this done as this was the car's second timing chain and the car had 450,000 miles. This is the third timing chain on an original engine and transmission.
If you have done this before or have dedicated a significant amount of your life to cars and machinery maintenance in general, you shouldn't experience too much trouble with this. Since I am a man of Arts and other, more primitive and creative activities, I naturally had a lot of trouble with this. On one hand, I had the bug to get the car ready for winter so I wouldn't have to worry about breakdowns and such. On the other, I had terrible working conditions and a lot of stress.
Anyway, I could speak about this matter all day, but the bottom line is, be prepared and have a checklist of some sort like the one I will provide in this instructional.
The intention of this thread is to prevent the potential timing chain replacer from wanting to cause injury to the designers of both his own species and the car.

This is intended for a very inexperienced DIY-er who hasn't done anything like this before. This is supposed to be the fastest and least risky way of doing this job. Familiarize yourself with this mechanism so that you are clear on how it works:


..and the timing cover removed (not nescessary with this method):


Let's get started:

1.) Checklist

parts:
-a new timing chain with a master link (I used this).
-new valve cover gaskets (I used this)
-good weather (unless you have a garage..which I didn't)
-good vision
-something that helps you cope (singing/playing the blues worked great for me)

optional parts which you will tinker with anyway:
-spark plugs
-camshaft sprockets
-valve lifters/followers
-distributor connecting joint/ o-ring/ cap and rotor

tools:
-a good ratchet set obviously
-12 and 14mm sockets for removing valve cover and camshaft sprockets
-20-25mm socket for removing the chain tensioner(does anybody know the exact size?) if no socket, you can bend a pipe into a socket like I did
-depending on the method you use to connect and disconnect the timing chain, you will need something to grind off the crimped ends of the chain. I used a dremel electric tool. Maybe you could use a file, but I cannot confirm that
-to connect the chain I used two hammers: one large and one small, like one used for hammering copper
-vise grips of various sizes to lock the flywheel and cams (three)
-2 adjustable wrenches of reasonable size (they call them "French keys" in Europe)
-jack/jackstand
-some sort of a thin metal rod to check the tension of the timing chain where you can't reach it
-acetone and scotch-brite to clean head and valve cover surfaces
-metal wire of different sizes
-zipties
-different sizes of pliers
-other small general workshop tools

2.)Setting TDC

Top dead center is the point where a given piston has reached the top of it's travel during normal operation. To align the valves and pistons together so they don't hit each other and provide proper compression, you need to align the marks on the camshafts with the mark on the flywheel perfectly. This sets TDC for cylinder #1, which is the one closest to the firewall.

There is very small chance (one in 1,000,000,000,000,000) that the engine will be set to TDC when you begin working. So you might as well know how to do it:

-Pull the handbrake tightly and jack up one front wheel. Put the car in 5th gear. Rotate the engine only counter clockwise when viewed from the front.Rotate the engine only one way. Rotate the last few inches with a screw driver. Don't ever rotate the flywheel backwards as that creates slack in the chain!

-Remove the spark plugs to eliminate compression so the engine can be rotated easily. To find cylinder #1's top dead center, you can either use the timing mark on the flywheel, or mmoe's method which consists of placing a straw inside cylinder 1's spark plug hole and noting when the straw stops rising. The straw will make contact with the piston and that way you can see exactly when the piston is at its highest point. Obviously, make sure the straw is long enough.


If you are going to time it according to the flywheel mark, use mark "B" on the top of the clutch plastic shield:



And align it with the "0" mark on the flywheel (clutch shield removed for clarity):



Now, to lock the flywheel, you can use different methods. You can use the genuine saab flywheel locking tool, or the quick-grips. Any way of snugly locking the crankshaft will work. I used quick grips.

To lock the flywheel with this method (or the special saab tool method), you have to remove the plastic shield.
To do this, you have to remove the various turbo pipes (if you have one), the AIC-to-throttle body hose, and the air mass meter and hose to gain access to the shield. There are bolts holding it to the engine block. There will be differing bolt sizes depending on the year, and there are three bolts. Your car may have more. Just make sure you get all of them as some are tricky to see.
Now removing the shield can be tricky, but don't be afraid of twisting it. It won't break. Just rotate and twist until it comes loose.

Now you can apply the quick grips:



It's actually better to use the passenger side of the bellhousing. Make sure not to move the flywheel more than a few millimeters when locking.

3.)Remove valve cover

Loosen all of the 12mm bolts on the valve cover, unplugging the spark plugs before commencing. Don't drop the bolts as the c900 is notorious for its appetite for bolts. I have lost many things in the various caverns, finding them months later.
If the valve cover hasn't been removed for a while, you will have to tap it off the head. You can use here either a rubber mallet or a wooden block and generously sized hammer. It will come off. Hit hard.
If you are going to reuse the gasket, then be careful when lifting it off. Remove the half moon rubber pieces first.
Be careful not to nick any camshaft parts when you are lifting it off.



4.)Removing the tensioner

I had the new style timing chain tensioner. This is the source of numerous problems with these cars. There is a tricky step in the reinstallation which I will explain later on. What it does is it basically puts tension on the plastic guide which tensions the chain. It consists of a pushrod and a ratcheting mechanism. There is a good guide on this site on how to deal with it.
Remove the small bolt, which I think is the same size as the valve cover ones.
Don't lose the plastic insert and spring, even though they are kind of useless.

I personally think the design of the tensioner is not very logical. The hex portion of the body is too close to the block. That way it's impossible to use any sort of wrench in there. I don't understand why isn't the whole body "hexed"...A very large socket is needed to remove this. Make sure it's the right size or you will might round the bolt off, making it difficult to break loose. If you can't find a right socket, but you have one that is relatively close, you can place a thin copper segment in the socket to aid in the good fit.
Unbolt the tensioner.

5.)Splitting the chain

Place a reasonably sized rag in the timing chain chasm and cover any sensitive objects nearby with towels. Tie some secure wire to both sides of the chain so you don't lose it down the engine. Tie the tensioning guide on the drivers side with wire so it doesn't get in the way:



Choose a link between the two sprockets and grind its crimped ends with a dremel tool. You might have to separate them with a knife. Please don't drop the knife or the flange down the engine, or I will strangle you.

6.)Camshaft Sprocket and camshaft removal

After separating the old chain between the sprockets, you have to connect the new chain to the old one so you can roll it through the engine. This way the new chain will be in the place of the old one. If you leave the sprockets and camshafts on, you will definitely bend valves. I don't see how you can keep the chains properly tensioned when you are rolling it through.

Therefore, you have to loosen the camshafts so that no valves are open and you can rotate the engine as much as you'd like without worrying about valve to piston contact.
This sounds like a big deal, but it really isn't. All you have to do is loosen all of the bolts on the camshaft bearing caps so that the cams aren't holding any valves open. Remove the sprockets first, so that you can access the leftmost bearing cap bolts.
To remove the sprockets, hold the camshafts still with a wrench and loosen a sprocket bolt on the other side. Don't move the camshafts too much, or you will make a valve contact a piston. They are very tight, and its better to use one brisk motion to break the bolts, rather than trying to press on the ratchet using your body weight.

Here are the flats on the camshafts where the wrenches go, and keep track of the dog on distributor drive. Don't let it get out of position or you will have your ignition timing 180 degrees off:



You don't need to remove the camshafts or bolts completely, unless you want to inspect the caps and surfaces, but loosen the bolts enough so that there is vertical play in the cams and none of the lifters are pressed. Make sure, again, that you don't drop any bolts in the spark plug holes (which should be covered with a rag by the way!), or in the frame cavities.
No need to completely remove them:


Last edited by nuclear944; 28th November 2010 at 01:58 PM.
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  #2  
Old 27th November 2010
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7.)Rolling the new chain in

This is where things got buggered up for me. When connecting the new chain to the old one, make sure that whatever you use to connect them is very strong.
DO NOT USE A ZIP TIE!!!
My zip tie broke exactly at the crank shaft sprocket so I ended up with a chainless engine. Contact me or member 900t if you find yourself in this situation.

Using good secure wire to connect the chains together is your best option. Unlock the flywheel and rotate the new chain through slowly, making sure that its not binding and such. Use the wire method again to anchor the new chain to the engine once it has taken the place of the old one.
Disconnect the old chain, but don't discard it yet.

Lock the flywheel at TDC again, rotating it only one way.

8.)Connecting the new chain

Hopefully your chain came with the master link and a new flange (credit to godol):



Mine didn't. So I used the flange from the old chain. If you buggered up the old flange, grind off a new one.

You can use the approved chain connecting tool, or the hammer method.
The hammer method consists of a large hammer serving as contra and a small one to squash the ends. You might a need a helper to hold to large hammer while you hold the chain against it. This gives you a very strong link, perhaps stronger than a regular one.

8.)Putting the chain on the sprockets

Now remove all the metal wire and make sure the cams are at TDC before you tighten them down (picture taken after cams and sprockets were tightened):



Tighten them down in stages, starting from the center. Tighten them enough but not too much (correct torque anyone?).
Now place the chain over the exhaust side sprocket, making sure that it engages with the camshaft. There is a notch on the sprocket, which should point at twelve o' clock:



You can ziptie the chain to the sprocket while you are tightening the bolt:



Don't torque it just yet.

This is where you can lock the camshafts using this rather primitive method:



Make sure everything is at TDC for cylinder #1 and lock everything. This is where you take off the slack from the exhaust side, one tooth at a time. Use the metal rod to poke the chain below and make sure it's tight.

Now use the same method to put on the intake sprocket. Tighten the bolt hand tight.

9.)Distributing the slack

At this point make sure that all of the slack is on the tensioner side of the engine. If you are one tooth off it will be very noticeable in the cam marks if you haven't locked them. Remember that the valve lifters can "pop" the cams around so you might have to keep tension on the cam with a wrench while you tension the chain.
Now place and tighten the tensioner body, making sure it's reset first.
Screw on the spring and plastic insert assembly and tighten.

Check to see if there is still slack at the tensioner side of the chain, above the guide.

Skip this step if there is no slack:

The tensioner may stick, causing slack in the chain, and therefore screwing up the timing.
If this happens, remove the spring and plastic insert again, carefully remove the tensioner again and very gently extend it one more tooth.
Screw on just the tensioner again and check for slack on the intake side.
Repeat this procedure until there is no slack. Tighten down the tensioner and spring. Don't forget the sealing ring!

10.)Final check

Now unlock everything, and make sure that there is:

a.) no slack between the crankshaft sprocket and exhaust side sprocket, no excessive slack between the cam sprockets, and no slack between the intake side sprocket and crankshaft sprocket
b.)that all of the marks are well aligned- no more than 5-7mm departure
c.)that the distributor rotor points towards cylinder #1 at TDC
d.)that the sprocket bolts are tightened/torqued

Rotate the engine, watching the camshaft markings. Rotate counterclockwise viewed from the front. Pray. When the camshaft marks meet, make sure that the flywheel marking is right.

If things are off, lock the flywheel at TDC once again, remove the spring and tensioner, and repeat step 9. It's easy to move the chain between teeth. Do one tooth at a time per every final check (step 10) you do.

11.)Magnifico!

If step 10 was successful, you are sincerely awesome.

Now you can put back the valve cover, using a good anearobic sealant. Place the spark plugs and wires. Put back the clutch cover and all the piping and make sure the air mass meter and AIC hose is on.

Assuming that the car starts and runs smoothly, congrats, you are a winner.



Sincerely, Rado Borisov

Credits to: euromobile900, 900t, Jeff Cullen, Jim Mesthene, peva, and others.

Last edited by nuclear944; 28th November 2010 at 04:53 PM.
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Old 28th November 2010
James Bond James Bond is offline
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Brilliant, many thanks.
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Old 28th November 2010
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Very nice writeup, Nuclear! It will be the definitive c900 timing chain post on the internet. I like the pictures of the head with cams loosened. Never seen pics of this before, even though I've seen it in person. Well done! We need this in the FAQ thread.
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Old 28th November 2010
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This is a nice write-up indeed and a good candidate for a sticky. You can't beat some good photos. Well done. Come on you Mods.
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Old 28th November 2010
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Thanks mates, I ironed out some of the messy bits and added my name. I hope this meets the FAQ standarts!
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Old 30th November 2010
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And to think I ready messy tits.

That made me put the coffee cup down and read again.

Great writeup! It makes me want to go and try checking my timing again and see why my white Saab does not want to fire up.
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Old 30th November 2010
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I don't understand the parts about locking the Flywheel or Camshafts.
I've replaced dozens of Chains and it never occurred to me to lock any parts in place. What's the point?
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Old 30th November 2010
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Quote:
Originally Posted by Jim Mesthene View Post
I don't understand the parts about locking the Flywheel or Camshafts.
I've replaced dozens of Chains and it never occurred to me to lock any parts in place. What's the point?
That's because you've done it so many times...when you are a beginner you have to eliminate the possibilities of potential processes that are out of your control.
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Old 30th November 2010
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Again, what's the point?
What problem are you avoiding by locking those parts in place? If it's a step-by-step guide, what's the point of that step?
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Old 30th November 2010
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You are preventing them from moving when you are positioning the timing chain.

When you are distributing the slack, the cams or crank can move, setting you away from TDC. It makes everything more positive and eliminates the risk for slack developing in the chain.
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Old 2nd December 2010
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The DOHC Honda engines I messed with had a hold on the front cam cap and the cam itself. The idea was once you had the head at TDC, you could drop a 5mm pin to hold cam in place while you played with the belt. I think the Volvo whiteblocks do the same. I think my Renault had something similar, but it would lock the crank.

An experienced mechanic probably would laugh at that (and think timing marks are for babies), but an amateur one like me really appreciates to have something like that to help setting things up right.
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