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Discussion Starter · #1 ·
My daughter has a '05 Cobalt with the 2.2 Ecotec and about 100,000 miles on it. My question is as the title states: what is the interval for changing the Timing/Balance Shaft Chains/Sprockets? I don't drive the car and as far as I know there aren't any problems as yet but to be honest she's fairly clueless about cars and I won't be notified of a problem until she's sitting beside the road.

So is this a concern? I can do the work - that's no big deal but it is a big pain (and rather expensive). If it's not necessary so be it - I'm not looking for extra work. I did have a '94 Skylark that lunched the valves at about 130,000 because the tensioner failed. I would like to prevent something similar if possible.
 

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You should not have to service chains like you do belts unless there is a problem. I would certainly consider replacing the tensioner since the 05 had an inferior model. Auto or manual?
 

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Does she still have the owners manual. I wonder if the maintenance schedule has any reference to the timing chain service intervals.
 

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Discussion Starter · #4 ·
You should not have to service chains like you do belts unless there is a problem. I would certainly consider replacing the tensioner since the 05 had an inferior model. Auto or manual?
It's an automatic. I had thought about going with just a new tensioner as well. I use Mobil 1 5W30 (or 0W30) and change it when the ECM says to change it. It doesn't really use any between changes. She bought it in '08 with about 38,000 on the clock so I would like to think it's been fairly well maintained. lol

The only serious problem we've had with it was a misfire that had me pulling my hair out for a few months but I finally got that straightened out.

---------- Post added at 04:13 PM ---------- Previous post was at 04:12 PM ----------

Does she still have the owners manual. I wonder if the maintenance schedule has any reference to the timing chain service intervals.
She has the owners manual but she's not here at present. I doubt it would be in there anyway. Perhaps I'm just being paranoid but I would rather be safe than sorry. I just don't know whether or not it's something I really need to be concerned about.
 

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All I know about these and timing chain is they don't like low oil levels. These engine prefer overfill than running low. The oiler at the top of the chain system will start to sludge up and eventually clog if engine is run low on old oil. So if yours runs good and doesn't lose too much oil between oil changes, you should be good for a while yet. But understand that with 100,000miles you should check the oil a bit more regularly.

---------- Post added at 05:41 PM ---------- Previous post was at 05:20 PM ----------

Just dug this up on tensioner concerns. Old tensionners weren't bad they just changed the design to eliminate "O" ring.



---------- Post added at 05:44 PM ---------- Previous post was at 05:41 PM ----------

Here's a funny little paragraph added at the end of that Bulletin.

GM bulletins are intended for use by professional technicians, NOT a
""do-it-yourselfer"". They are written to inform these technicians of
conditions that may occur on some vehicles, or to provide
information that could assist in the proper service of a vehicle.
Properly trained technicians have the equipment, tools, safety
instructions, and know-how to do a job properly and safely. If a
condition is described, DO NOT assume that the bulletin applies to
your vehicle, or that your vehicle will have that condition. See your
GM dealer for information on whether your vehicle may benefit from
the information.
 

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Discussion Starter · #6 ·
All I know about these and timing chain is they don't like low oil levels. These engine prefer overfill than running low. The oiler at the top of the chain system will start to sludge up and eventually clog if engine is run low on old oil. So if yours runs good and doesn't lose too much oil between oil changes, you should be good for a while yet. But understand that with 100,000miles you should check the oil a bit more regularly.
I appreciate the information. I guess I'll just leave it until I have signs of a failure.

Just out of curiosity, can the tensioner be replaced without removing the camshaft and timing chain covers? Looking at the diagrams it would appear that's possible but it's hard to say for sure.

Thanks again to everyone for all of the help.
 

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I don't think so, even if it just unscrews from the side, you are going to have to release the tensioner somehow once it's in place I assume. It is 72mm in full compression and 85mm extended. Let me check the server....

---------- Post added at 09:45 PM ---------- Previous post was at 09:26 PM ----------

As I suspected you need to remove the valve cover to release the tensioner from it's compressed setting. Here is the install litterature....

Installation Procedure


1. Inspect the timing chain tensioner. If the timing chain tensioner, O-ring seal, or washer is
damaged, replace the timing chain tensioner or O-ring seal as applicable.
2. Measure the timing chain tensioner assembly from end to end. If the timing chain tensioner
is to be replaced, a new tensioner should be supplied in the fully compressed non-active
state. A tensioner in the compressed state will measure 72 mm (2.83 in) (a) from end to
end. A tensioner in the active state will measure 85 mm (3.35 in) (a) from end to end.
3. If the timing chain tensioner is not in the compressed state, perform the following steps:
3.1. Remove the piston assembly from the body of the timing chain tensioner by pulling it
out.
3.2. Install the J 45027-2 (2) into a vise.
3.3. Install the notch end of the piston assembly into the J 45027-2 (2).
3.4. Using the J 45027-1 (1), turn the ratchet cylinder into the piston.
4. Inspect the bore of the tensioner body for dirt, debris, and damage. If any damage appears,
replace the tensioner. Clean dirt or debris out with a lint-free cloth.(Just replace it, original is no good anyways (my 2 cents))
5. Install the compressed piston assembly back into the timing chain tensioner body until it
stops at the bottom of the bore. Do not compress the piston assembly against the bottom of
the bore. If the piston assembly is compressed against the bottom of the bore, it will activate
the tensioner, which will then need to be reset again.
6. At this point the tensioner should measure approximately 72 mm (2.83 in) (a) from end to
end. If the tensioner does not read 72 mm (2.83 in) (a) from end to end, repeat steps 3-5.
7. Inspect to ensure all dirt and debris is removed from the timing chain tensioner threaded
hole in the cylinder head.
Notice: Refer to Fastener Notice in the Preface section.

Important: Ensure the timing chain tensioner seal is centered throughout the torque
procedure to eliminate the possibility of an oil leak.
8. Install the timing chain tensioner assembly.
Tighten
Tighten the timing chain tensioner to 75 N·m (55 lb ft).
9. The timing chain tensioner is released by compressing the tensioner 2 mm (0.079 in) which
will release the locking mechanism in the ratchet. To release the timing chain tensioner, use
a suitable tool with a rubber tip on the end. Feed the tool down through the cam drive chest
to rest on the cam chain. Then give a sharp jolt diagonally downwards to release the
tensioner.
10. Install the camshaft cover. Refer to Camshaft Cover Replacement .
11. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and
Connection .
 

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Discussion Starter · #8 · (Edited)
I don't think so, even if it just unscrews from the side, you are going to have to release the tensioner somehow once it's in place I assume. It is 72mm in full compression and 85mm extended. Let me check the server....
Thanks. It was a dumb question. As soon as I started reading that I remembered the whole "suitable tool with a rubber tip" part and thinking that was rather odd. I guess I'm just tilting at windmills here and I'll just let it go until there are actual symptoms of a problem. I appreciate all your help. God bless.
 

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don't wait until it fails to replace it, you can bend valves and screw up your pistons, then you're looking at hundreds of dollars to fix. tensioner is like 30 bucks and can save you 1000. simple to do, get it done
 

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Ya. Maybe I didn't make it clear. Don't need to fix the chain, its the tensioner that needs to be replaced.
 
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