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Discussion Starter · #1 ·
My 1998 Saab 900s (130K miles) has been rattling on the timing chain side of the engine for several years but I didn't notice any performance issues so I let it ride. However, half way home from work yesterday it started coughing and nearly died at each stoplight. All the spark plugs are firing without pauses according to a timing light on each plug wire so I think the electrical is fine. I figured it's time to pull the valve cover and see what the chain looks like.

Here is a link to a short video showing the timing chain:
http://youtu.be/iWPl5qyQwKI

The chain links are each sitting at a slight angle to the plane of the cam gears. From what I've read on other threads here, this means the chain is stretching. The tensioner is fully extended but the chain doesn't seem that loose when I pull on it.

I have a new non-continuous timing chain on order and intended to replace only it (1 hour job). However, I'm wondering if I should pull the engine and replace all the guides and gears as well (3 day job).
 

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Discussion Starter · #2 ·
So I did the timing chain pull-on this morning. I started with the engine at top dead center (TDC). (first image)

I broke one of the old chain links with a Harbor Freight chain breaker and hooked in the new chain to the end of the old chain. My son turned the flywheel (clockwise) while I made sure to keep the chain tight the entire time. When the new chain end made it's way around to the top again, I verified that everything mated up correctly. The ends of the new chain matched up correctly (not off by a tooth) and the copper/yellow links sat right on the cam gear marks. However, after installing the chain tensioner and hand turning the flywheel through a few revolutions and stopping at TDC, the cams are now each a few teeth off. (second image)

Later this afternoon I'm going to simply break one of the top links and set the cams at TDC (12 o'clock on each cam gear mark).

Someone please let me know if there is an easier/better method to get the crank and cams aligned at TDC.
 

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Discussion Starter · #4 ·
Why turn the crank 90 past TDC and then turn it back at the end? Valve clearance?

Do I need to remove the tensioner to get some slack before removing the cam gears?
 

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Discussion Starter · #6 ·
Worked great. Thanks for the advice. For those needing detailed instructions:
1) Remove the tensioner spring assembly (12mm socket) and then the tensioner housing(27mm socket).
2) Using the bolts on the flywheel, turn the crankshaft about 90 degrees past TDC. Always turn clockwise. This assures that none of the pistons are at TDC so there won't be any concern about the valves hitting them when you manually turn the cam shafts later.
3) Remove the two cam gear bolts and cams. There are wrench flats on the righthand end of each camshaft to hold the camshaft steady when removing the cam gear bolts. Once the bolts are out, use a long flathead screwdriver and hammer to gently tap the back of the cam gears to remove them from the shafts. It doesn't take much.
4) Using the wrench flats at the righthand end of each camshaft, turn the cams to TDC aligning the marks on the shaft with the mark on the left-most bearing housing.
5) Now that the cams are at TDC, have someone turn the flywheel clockwise while you keep the chain tight so that it doesn't bind at the crank shaft gear below. Turn until the crank pulley mark lines up with the timing cover marks (looks like sights on a rifle barrel).
6) Reinstall the front cam gear first (closest to the front of the car) keeping the chain tight up the righthand side of that gear (standing on the passenger side of the car). You want to end up with all the chain slack on the lefthand side of the back cam gear so that the adjustable guide there can take up that slack. Use a hammer to gently tap the gear in place.
7) Reinstall the back cam gear keeping the chain tight between the two cam gears. Use a hammer to gently tap the gear in place.
8) Install both cam bolts.
9) Install the tensioner housing (without the spring assembly) making sure that the ratcheting extension is not extended.
10) Install the tensioner spring assembly.
11) Use a long flathead screwdriver to gently lift the adjustable chain guide to take up the chain slack. You should hear the tensioner click as the spring pushed the extension arm out to keep that guide in place.
12) Using the flywheel bolts, turn the engine through a couple revolutions and stop when the crank pulley mark lines up again. Double-check the cam marks to assure yourself that everything is still lined up.
 

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Glad you got it resolved. Does it sound any different/better after this install?..Did you only replace just the chain?. Did you check to see if the chain tensioner is still fully extended after the new chain was installed? Ive had thoughts on this before, so, im curious as to your results..
Thank You
 

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Discussion Starter · #8 · (Edited)
I have the valve cover back on but according to the instructions on the sealing compound, I hand tightened the cover bolts, waited one hour for the compound to film over, and then torqued them all down. I'm supposed to wait 24 hours for it to cure completely but I figure overnight will do.

Anyway, I was putting the spark plugs back in and one of them broke apart. Half of it is threaded tight in the spark plug hole and the other half came out in the socket drive. I bought four new spark plugs but cracked the ceramics on one of them while installing. I guess I wasn't torqueing it straight up and down. Therefore, tonight I was temporarily going to reuse one of the old ones and that is the one that broke in half. I'll go to the auto part store tomorrow and buy a new spark plug along with a "broken bolt remover". That should do the trick.

To answer your questions, I only replaced the chain using the "pull on" method. The guides looked okay. There were very small ridges in them but not deep at all. Going through the process of getting all of the timing marks lined up, I installed and removed the tensioner multiple times. Thankfully it is easy to get to. With the new chain on, it was extended approx. 5-6 clicks.

I'll post tomorrow after I get the spark plug replaced and try to start the car.
 

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So the threaded part of the plug break off below the flats? If so, I have never seen anything like that. Hopefully, the threaded part is not cross threaded in the head... Ron
 

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Discussion Starter · #10 ·
I used an "easy out" to remove the threaded bottom half of the broken spark plug. Yes, the entire ceramic portion from the upper electrode to the lower electrode came out as one piece along with the wrench flats.

With everything back together, it started fine (halleluiah!) and drove fine around the neighborhood. With the chain noise gone, I can clearly hear a loud ticking from the #3 exhaust lifter/valve.

The timing chain had to be replaced since the tensioner was completely extended so no regrets there. Now I have the 'opportunity' to learn how to repair/replace lifters.

The car sat idle for only 3-4 days while I waited for parts and worked on the timing chain so I don't think the lifters dried out. Any advice before I dig in like "wait a couple days to see if it quiets down?"
 

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The WIS says to let the engine run for 20 minutes or so to work the air out of the lifters (aka cam followers), so it will probably quite down in a little while... Ron
 

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Discussion Starter · #12 ·
I drove it gently to the auto parts store and bought some engine flush, new oil, and oil filter. By the time I got home the ticking was not nearly as pronounced but still there. I'm doing the 5 minute flush now and will add some Lucas oil treatment with the new oil as I've read in different threads here. I'll then give it a few days before I post the results of whether the lifter quieted down any more.
 

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For future reference, install the valve cover gasket without sealer whenever possible. As long as the gasket is fresh, it will be fine and you won't have to spend an hour or more carefully scrapping gasket sealer from the cover and head next time.

The only thing you need sealer for is to hold the gasket into the cover long enough to install without it falling out when you turn the cover over.
 
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