Replaced my timing chain tensioner today and now my car won't start. During replacement, the chain jumped teeth and my timing got off. Now, I think I have the timing back on track but it still won't start. Went through and checked all the fuses and none of them are blown. Did a check for a spark and found that the plugs are indeed sparking, there is pressure in the fuel line and fuel is coming out the exhaust, so I think the pistons are getting fuel and a spark. Does anyone have any ideas?

 

believe have to line up all timing "dots"(cams, crank, chain)

 

may have bent valves...ask me how i know

this exact thing happened to me...and i had to replace the head.
get a compression tester and test..if no compression then the head needs to come off

if you are building some then your valves arent seeling....
if its still high then look into other options

 

yeah, take your timing cover back off and check your timing before turning your engine over again! cobalts have interference engines which means the pistons WILL hit the valves. make sure your dots are lining up perfectly on the crank and cams, just one tooth off will mess everything up. and make sure your timing chain is seated well on the sprockets

 

If you turned it over with timing off start looking for a used head. The valves are probably bent and it will be cheaper than replacing them.

 

I dont understand how this tooth jumping is happning unless you are starting the car with no tension on the chain and using the chain slap of reving the car to reset the tensioner.
The procedure for the tensioner replacement specifies taking off the valve cover and reseting the tensioner with a long screw driver so that there is tension on the chain before starting the car.

Can someone elaborate on why this is happening to people!

Also Dont you guys think if the Valves got bent he would of heard something.

 

Thanks for the input, some buddies and I are going to take a look at the timing again and do a compression test after work today.

 

if you take the tension off the slack can drop around the crank and shift it one or a few links, it only takes 2 or 3 before the pistons meat valves...i have pics around here somewhere but when it happened to me all my valves bent 30 deg over and impacted into the combustion chamber on the head....


good thinking to test out today, be careful incase nothing has been damaged yet. make sure and take out the fuel pump relay in the under hood fuse box when doing the test...best to not flood out your engine...could get a REALLY nasty backfire with all that fuel in there.

 

Make sure the timing is perfect before you do the compression test. It would suck to bend a valve while running the test if it hasnt already happened.

 

Ok boys and girls results are in... intake valves are all bent. So, if you do decide to replace the timing chain tensioner please be aware that when replacing it your timing CAN jump and will cost you $$$.

Now, I also found a timing guide that screwed into the head was sheared off and created wear on the head so maybe the bad tensioner caused this to happen, or vice versa, I'm not sure.

 

Did you use the new style, or old style, tensioner?

Not trying to be a dick, but it was probably user error during installation, on your part. And if you got the old style that would have been another error.

Explain the steps you took when replacing it, and I can tell you, where you went wrong. It's very common that these tensioners are installed wrong, or with little care. Ignorance is bliss.

 

sorry to hear that...played that game before

 

that sucks dude

 

Im not sure, I just went to auto zone and told them I needed a new timing chain tensioner for a 2006 ss/sc cobalt. I not ruling out operator error, that's why I have to pay for a new head is because I didn't take the time to research proper installation. I just got onto a forum here and failed to realize my timing got off and try to start her.

As soon as I took the old one out it jumped. Apparently, it still was holding some tension but was still seized up upon inspection. I think it jumped so bad because I didn't notice the rattling right away and I was driving around for almost a week (I think) like that. I am betting the chain kept slapping up against the other guide (the one that screws into the head), sheared that off thus creating more slack. So, when I finally pulled the tensioner, the chain between the cams was nice and tight whereas the chain between the crank and intake cam was very loose.

Found a nice used head though, so some good news there.

 

Good, well I'm very glad you found one, [a head]. That can be really pricey.

Did your new tensioner look like this?



Or this?

 

The second is just an exploded view of the first correct? But, they both looked like that.

 

no, the second is the old style, the first one is actually hydraulic and does not come apart like that

 

For reference, if you take the valve cover off, you can turn the motor over by hand until the cams aren't holding a ton of tension on the chain. Where the motor stops may not be a safe place to remove the tensioner if you just shut it off and tear it apart. Bring it up to a neutral point where there aren't any valves open to take the pressure off the cams.

 

x2

I don't know if it's correct or not, but i also used the hex on the cam to roll the motor over and set the tensioner (I sucked at getting it to release by tapping on it..lol)

 

Thats what those hex's on the cams are for, to hold or turn them. You don't just tap the tensioner, you have to whack it pretty well to get it to pop lol. It's not a subtle release either, you'll know when it engages. I also installed one already released, but that was with the motor out of the car so it was easier.

 

Is there any chance you can replace the valves themself and not have to but a whole new head? Or did it mess up the head itself?

 

Heres the Procedure ,right out of the manual.
When some ones having trouble could it be from not setting the tensioner and starting the car?
the procedure is pretty straight forward!

1. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection .
2. Remove the camshaft cover.
3. Remove the timing chain tensioner.
4. Remove the seal from the tensioner.

Installation

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.
8. 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.
9. 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.
10. 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.
11. 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.
12. Install the timing chain tensioner assembly.
Tighten
Tighten the timing chain tensioner to 75 N•m (55 lb ft).
13. 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.
14. Install the camshaft cover. Refer to Camshaft Cover Replacement .
15. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection .

 

You can remove the spark plugs, and take the valve cover off. When you remove the tensioner, the motor is going to go where it is most "comfortable" anyway. There is no compression so there would be no reason for it to jump teeth at all.

Another thing is because people unscrew the old tensioner like a freaking mad man, which you are NOT supposed to do. All you need to do is break it loose from the block, and unscrew it SLOWLY. You can visually see the chain SLOWLY losing tension. I suppose if you unscrewed the thing real fast it could jump but while you're unscrewing it, there should be indication whether or not the cam is going to move, in which you should probably stop and assess the situation by turning it by hand [the motor] a little bit. So if the cam shows no signs of moving, then keep going, but if you see it wanting to move, stop. It really shouldn't though. Not with the plugs out. You're not trying to fight compression so I don't see how this is happening. Nor have I ever heard or seen it personally. It's 99% user error.

That would be the old style. The new one does not require being "set".

Incorrect.

Correct.

 

For the millionth time. That is for the old tensioner. I got the same information from AllData. For the new tensioner, there is no guide lines, per say. Everything I put in BOLD is not needed with the new tensioner. I have went over this with GM techs multiple times for accuracy.

 

A timing guide screw sheared off and wore the head a bit. So, better safe than sorry and buy a new (used) head. I was quoted 600 for all new intake valves and 500 for the used head with the valves included, so cheaper to buy used. I am assuming that I will send off for a valve job on either choice.

"Another thing is because people unscrew the old tensioner like a freaking mad man, which you are NOT supposed to do. All you need to do is break it loose from the block, and unscrew it SLOWLY. You can visually see the chain SLOWLY losing tension. I suppose if you unscrewed the thing real fast it could jump but while you're unscrewing it, there should be indication whether or not the cam is going to move, in which you should probably stop and assess the situation by turning it by hand [the motor] a little bit. So if the cam shows no signs of moving, then keep going, but if you see it wanting to move, stop. It really shouldn't though. Not with the plugs out. You're not trying to fight compression so I don't see how this is happening. Nor have I ever heard or seen it personally. It's 99% user error."

What I did to remove the tensioner:
1. Take off valve cover
2. Remove spark plugs
3. Unscrew old tensioner, (and no, not like a "madman"),

This is all that caused my timing to jump. My chain was extremely taut between the cams, and extremely taut between the exhaust cam and crank, buy very loose between the crank and intake cam. Thus, when I unscrewed the old tenioner (which was still holding tension) the chain jumped to equalize the slack between the crank and intake cam (or between the cams not really sure which way it jumped). My car could have been in gear at this point I don't remember, so maybe that's why it jumped. So, I would disagree to say its 99% user error that my timing jumped. However, it was my fault that I bent my valves, I should have been more careful when I suspected the timing jumped.