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What is the recommended intervals for changing the timing chain on a 1987 Saab 900s??? It seems to be fine now and i have like 115,000 miles on it now......Anyone? :)
 

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150,000 miles / 250,000km.

There is a tensioner, you check the measurement on that. At 150,000 there should be about ripe for a change, 11mm on the tensioner plunger.
 

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I just hit 200,000 miles today, still with the original chain.. I'm thinking of replacing it soon though, I don't want to push my luck too hard.
 

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As already said, the best thing is to check tensioner extension occasionally--every, say, 50k miles. Mine is still fine at 267k (last checked at 260k miles--extension was 9mm; 11mm permitted).
 

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Timing Chain

I have just heard from the young man who is taking over my 1980 900 Turbo (199500Km) that the timing chain had broken because the water pump which had just been fitted before the car broke down was badly fitted! The chain could have lasted twice as long!
 

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I am in the process of replacing the seals on my chain tensioner. The distance from the bottom of the body to the top of the plunger measured 19.25mm. The spec. is no greater than 11 mm? Anything greater requires timing chain replacement?

I am surprised as the vehicle just passed 100k miles and I've only used Mobil1 synthetic for the life of the car. There are no chain sounds and the engine runs very smoothly.

Am I missing something?
 

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I loosened the 13mm bolt to make sure I could unscrew it after I removed the tensioner. I didn't remove the 13mm bolt until after I removed the tensioner body.

I cleaned the tensioner and replaced both the seals. With the 13mm bolt removed, I made sure the plunger was working properly by pushing the indent and then pushing the plunger back into the body. I did this twice.

With the plunger in the body, I reinserted the tensioner into the block. I put the spring in, pushed down and then started to screw in the 13mm bolt. I heard the plunger click down as I tightened the 13mm bolt. I repeated the procedure a second time to make sure the plunger dimension depth was the same. I was afraid that if the plunger did not go back to its original depth, it could allow the chain to jump a tooth.

I'm just confused why my plunger depth of 19.25mm is so high.
 

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You need to fully remove the 13mm bolt before doing anything to the tensioner body. Otherwise the spring will continue to act on the tensioner, and force it out further as you unscrew it. Remove the 13mm bolt, release the cam, depress the plunger, put the tensioner back in the engine. For this purpose, finger tight is probably fine. Then install the 13mm bolt to set the tensioner. It would be a good idea to turn the engine a few revolutions by hand. Then, remove the 13mm bolt ENTIRELY along with the spring and THEN the tensioner body and take your reading.

If your tensioner was truly at 19mm, that engine would be noisy AF.
 

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Thank you for the clarification. That makes sense. I put the A/C compressor back on with the belt last night and drove it to work today. Runs so smooth. The biggest improvement is that the new belts make the car so quiet sitting at the light. No other noises to note. No oil leaks on the ground. Yay!

I will change the oil and filter tonight that I used with the Vaseline packed oil pump and put in some fresh Mobil1 synthetic.

I'll check the measurement correctly next time I'm doing work under the A/C compressor. With no abnormal noises, using synthetic oil for the life of the car, and only 100k miles, I'm not concerned.

The 27mm socket was a bit loose but did the job. Is that a US size hex on the tensioner body?
 

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27mm is the right size.

Hopefully you removed the bolt entirely before reinstalling the tensioner. If not, you're going to cause some problems.
 

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Initially, no. I was reinstalling the tensioner body by hand and felt it bind. I saw on the forum here the warnings about the potential for damage if not installed properly so I removed the tensioner body and then removed the bolt and spring before reinstalling the tensioner. I can see how this can cause problems if not done correctly.
 

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Yeah - you would break the tensioner or the timing chain guide. Either way, you'd be fishing debris out of the engine. No fun.
 
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