Timing Chain Tensioner: The REAL How-To - Cobalt SS Network



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Old 03-20-2012, 09:50 AM   #1
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Timing Chain Tensioner: The REAL How-To

When switching to the new style tensioner, do NOT just plug and play the new one. Removing the tensioner creates enough slack in the chain for the engine to skip timing on startup. This can especially occur if the cams are resting in a position where they are sprung against each other. I tried this method because many on this forum have tried it with success, but they were very lucky.

If you want to do this right:
-remove the valve cover
-place a zip tie through one of the bottom holes on the intake cam sprocket around 7 o'clock
-wrap it around the chain under the exhaust sprocket, and tighten.
-then when you remove the tensioner, the chain is still in tension and will not skip timing.
-install new tensioner and remove zip tie
-install valve cover.

Perhaps this should be a sticky, because it seems to be the consensus on this forum that you can simply unscrew the old one and put the new one in. I just spent $500 in parts to fix my bent intake valves which was the result of using this method. A forum member suggested my timing chain may have possibly stretched, so I bought a new one. I measured the new against the old, and they were identical, so that is not the source of error here. It is the procedure. I hope others can learn from my mistake. If you lack the ability to do a head change yourself, this could end up costing you at least 3-4 times as much as it did me should you use the plug and play method.

Last edited by SaberD; 03-20-2012 at 09:56 AM.
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Old 03-20-2012, 09:53 AM   #2
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Nice write up, i've seen some crappy ones before
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Old 03-20-2012, 08:06 PM   #3
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^I agree...

After all the posts I read on here about"oh just take out the old one and pop in the new one"

I didnt believe it so I went to the local pick and pull and tried a few to see how the timing chain reacts when you take the tensioner out. 2 out of 3 fell off the bottom sprocket. One was tight enough it moved a bit but not enough to fall off. So those 2 engines could have been catastrophic failures.

I used a flat blade screwdriver on the tensioner guide and that worked to keep the tension but I like this idea.
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Old 03-20-2012, 08:10 PM   #4
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you forgot to add in that you have to press on the chain guide to release the new tens.
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Old 03-20-2012, 08:46 PM   #5
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?Thats if you have it in the locked position but you can leave i in the extended position just fine.
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Old 03-21-2012, 12:12 AM   #6
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Do you wanna do mine for me, Saber?
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Old 03-21-2012, 11:48 AM   #7
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Do you wanna do mine for me, Saber?
I can in a couple weeks. I have like half of my tools at a friend's house right now though. We are chainging out the clutch in his s2000, and waiting on parts at the moment. Send me a pm in a couple weeks if you are still interested, and I'd be happy to help you out.
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Old 03-21-2012, 11:53 AM   #8
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idk i just did it the simple way at least 8 months ago and nothing's happened. just unscrewed the old one... screwed in the new one! guess i'm one of those lucky few huh
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Old 03-21-2012, 11:59 AM   #9
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same here, but hell even my new CEd tensioner makes the same/simular noise my old one did, but just not as loud and it does go away. i only get the noise after its sat for more than 5-6 hours and it usually only last the first 3-5 miles you drive the car, its not a constant noise, just at idle. prolly just another "cobalt" thing lol.
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Old 03-21-2012, 12:02 PM   #10
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Old 03-21-2012, 12:29 PM   #11
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It depends on where the cams land and how much you move everything when you take it out.

I always pull the valve covers, it's too easy to remove and not worth it to skip and end up with bent valves. I usually turn the motor over by hand until I can safely back it off a tad and get some slack on the tensioner side of the chain. That way you know when you release it it won't jump. Even with the valve cover off, if it jumps the only fix is pulling the front cover and resetting the timing properly, which is much more time consuming.

All in all, if this is something that you don't understand, i'd take it to someone who does. Too much risk if something happens to make it worth doing wrong. It's not a big job but carries a pretty big risk.
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Old 03-21-2012, 02:12 PM   #12
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Quote:
Originally Posted by advise View Post
you forgot to add in that you have to press on the chain guide to release the new tens.
wrong

Quote:
Originally Posted by cavfiredesire View Post
?Thats if you have it in the locked position but you can leave i in the extended position just fine.
wrong

the new tensioner dosent need to popped its a hydraulic tensioner

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Originally Posted by ItalianJoe1 View Post
It depends on where the cams land and how much you move everything when you take it out.

I always pull the valve covers, it's too easy to remove and not worth it to skip and end up with bent valves. I usually turn the motor over by hand until I can safely back it off a tad and get some slack on the tensioner side of the chain. That way you know when you release it it won't jump. Even with the valve cover off, if it jumps the only fix is pulling the front cover and resetting the timing properly, which is much more time consuming.

All in all, if this is something that you don't understand, i'd take it to someone who does. Too much risk if something happens to make it worth doing wrong. It's not a big job but carries a pretty big risk.
you do not need to pull the front cover to time a lsj there is a tdc mark on the front cover and a mark on the dampner

if you remove the old tensioner and it jumps time then you need to replace the timing chain and gear set because it is stretched beyond limits and the new tensioner will be 100% extended and not capable of doing its job properly by keeping enough chain tension not to mention the excesive loose chain will trow the cam timing off

Last edited by mrbelvedere; 03-21-2012 at 03:13 PM.
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Old 03-21-2012, 02:54 PM   #13
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if you remove the old tensioner and it jumps time then you need to replace the timing chain because it is stretched beyond limits and the new tensioner will be 100% extended and not capable of doing its job properly by keeping enough chain tension not to mention the excesive loose chain will trow the cam timing off
I bought a new chain, and the length of the old one was identical to the new. it was not because of a stretched chain.
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Old 03-21-2012, 03:12 PM   #14
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your gear set was worn which isent that common it mainly the chains that wear out but reguardless they should be changed as a set

Last edited by mrbelvedere; 03-21-2012 at 03:55 PM.
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Old 03-21-2012, 04:02 PM   #15
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you do not need to pull the front cover to time a lsj there is a tdc mark on the front cover and a mark on the dampner

if you remove the old tensioner and it jumps time then you need to replace the timing chain and gear set because it is stretched beyond limits and the new tensioner will be 100% extended and not capable of doing its job properly by keeping enough chain tension not to mention the excesive loose chain will trow the cam timing off
You can line up the bottom pulley, but how can you see the colored mark on the gear? You could easily be off a tooth on the bottom pulley and the top would still look right. Not worth the risk IMO.
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Old 03-21-2012, 05:06 PM   #16
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With the new chain on and the tensioner out, it hangs past the crank sprocket enough for the crank to rotate, and enough for the rollers of the chain to come unseated from the vallies of the crank sprocket teeth.

If the tensioner is installed when the chain rollers are above the teeth on the sprocket instead of above the vallies, when the engine is started, it WILL skip several teeth. It is quite obvious this is what happened.

I was even able to repeat this several times rotating the engine by hand without touching the chain. I even conducted the experiment with the old chain before i took it off. I had the exact same results with the new chain.

The sprockets looked practically new. If a completely stock engine needs a new sprocket set or timing chain at 65k, that is a serious design flaw, and I mean very serious. Timing chains typically last the life of the engine, and the sprocket sets should too. I'm talking 200,000+ miles.

The only reason why the chain would stretch excessively or excessive sprocket wear occuring would be due to modifications:
-stiffer valve springs
-higher lift cams
-higher rpm
-basically anything that allows the rpms to accelerate faster like an aluminum flywheel for instance
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Old 03-21-2012, 05:19 PM   #17
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I pulled out the old, put it the new. It runs great.
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Old 03-21-2012, 07:19 PM   #18
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I can in a couple weeks. I have like half of my tools at a friend's house right now though. We are chainging out the clutch in his s2000, and waiting on parts at the moment. Send me a pm in a couple weeks if you are still interested, and I'd be happy to help you out.
If you're being serious, I'll throw like $50 your way for your time.
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Old 03-21-2012, 07:29 PM   #19
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I pulled out the old, put it the new. It runs great.
ditto x 100 installs.
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Old 03-21-2012, 11:49 PM   #20
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You can line up the bottom pulley, but how can you see the colored mark on the gear? You could easily be off a tooth on the bottom pulley and the top would still look right. Not worth the risk IMO.
spin the intake cam to its install postiton aka as the relaxed positionspin the exhaust to its relaxed position ensure the the tdc markd are lined up pull the chain around to where the colored links need to be for the cams install intake cam gear with refrence marks line up then do the same for the exh cam and rotate the exh cam back into the cam gear thats the only way i do is with the cover on never had a problem but the more you do the easier it is to do i actulay seen how to do it in the gm sportcompact build book 3rd edition ive even had to time a couple of them by counting links because the anodized color on the refrence links was gone its 16 links between for the cam gears

Last edited by mrbelvedere; 03-22-2012 at 12:06 AM.
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Old 03-22-2012, 12:02 AM   #21
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With the new chain on and the tensioner out, it hangs past the crank sprocket enough for the crank to rotate, and enough for the rollers of the chain to come unseated from the vallies of the crank sprocket teeth.

If the tensioner is installed when the chain rollers are above the teeth on the sprocket instead of above the vallies, when the engine is started, it WILL skip several teeth. It is quite obvious this is what happened.

I was even able to repeat this several times rotating the engine by hand without touching the chain. I even conducted the experiment with the old chain before i took it off. I had the exact same results with the new chain.

The sprockets looked practically new. If a completely stock engine needs a new sprocket set or timing chain at 65k, that is a serious design flaw, and I mean very serious. Timing chains typically last the life of the engine, and the sprocket sets should too. I'm talking 200,000+ miles.

The only reason why the chain would stretch excessively or excessive sprocket wear occuring would be due to modifications:
-stiffer valve springs
-higher lift cams
-higher rpm
-basically anything that allows the rpms to accelerate faster like an aluminum flywheel for instance
i have seen the gears worn and the chain been just fine or the chain stretched and the gears are just fine on 60k engines a couple of them were never driven hard either ive pulled coveres on 110k plus engines and poped the tensioner out and there be very little slack in the timing set i think it is more luck of the draw on that but i do know that if the chain hangs off the crank gear far enough that either the chain is shot or the gears are shot and the stuff needs to be replaced and if the chain is hanging off the the crank gear far enough for it to jump time the tensioner will be extended all the way and wont be ably to keep propper tension on the timing set and that will cause problems when you install a new chain and gears the there is very little slack in the timing set so little that it can a pain to get the tensioner back in
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Old 03-22-2012, 03:44 AM   #22
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My Chilton manual gives some fairly explicit prep and install instructions, to each their own but I'll be doing this one by the book.
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Old 03-22-2012, 09:23 AM   #23
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If you're being serious, I'll throw like $50 your way for your time.
lol yeah im being serious. is it so uncommon for people to help out other forum members here? but like i said, i wont have my tools for a while, so send me a pm in a couple weeks.
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Old 03-22-2012, 12:26 PM   #24
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So overall on the average start to finish how long does it take to change the tensioner
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Old 03-22-2012, 01:10 PM   #25
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So overall on the average start to finish how long does it take to change the tensioner
I am assuming that this link would cover all the ecotec motors?
http://www.crateenginedepot.com/pdfs/12608580INS.pdf

http://www.crateenginedepot.com/pdfs/12608580INS.pdf
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So overall on the average start to finish how long does it take to change the tensioner

Last edited by bigjacksauto; 05-03-2012 at 09:28 AM. Reason: Automerged Doublepost
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