Any one familar with Ecotec engines?

[MY FYN 79]

My Ecotec 2004 Cavalier (102k) has the occasional mega rattle when it starts. No rhyme or reason, just does it. Sounds like a lot of people have this issue with Ecotec engines, only I believe mine is louder. Just lately (within the last week) it randomly gets a rattling noise at idle. With my handy stethoscope I traced the noise (when its making it) as coming from the timing chain cover.

Tonight I pulled the cam? cover off and everything looked peachy. No slack in the timing chain, upper guide looked good, but the engine was also quiet when I shut it off to pull it apart. I zip tied the chain to both upper sprockets for safetys sake and pulled the tensioner out. From the reading I've done, it appears this engine has the old style tensioner because after I pulled it out the guts fell out of it. Supposedly the updated tensioners guts are held in with a snap ring.

I'd like to try swapping just the tensioner to see if it could have been an intermittently sticky tensioner.... but has any one ever heard of that happening? I've read lots of cryptic things on these engines in the timing department, but seeing as how this one is perfectly quiet a good percentage of the time leads me to that conclusion about the tensioner.

Does the theory hold water?

Much thanks for any thoughts.

[stealthy1ss]

The old tensioners are garbage. Here is a link to the one that you need.

http://www.crateenginedepot.com/Ecotec-Timing-Chain-Tensioner-12608580-P10722C665.aspx

[lilws6]

poopy tensioner ive heard plenty that sound like there gana blow almost all the time. Altho those ones have been neglected on oil changes and what not. I'd start with the tensioner bet it fixes it :)

[stealthy1ss]

If it is not the tensioner it may be a chain guide.

[MY FYN 79]

Thanks for the tips.

I put in one of the updated tensioners tonight. Put an extension down in against the chain/guide and gave it a couple whacks. Seemed like the tensioner released so I buttoned it up. Car ran rough and shut off. Doesn't start now. Assuming the tensioner didnt actually release, did I just create myself a ton more work with a jumped chain? Damn.

[stealthy1ss]

You might have. The best way to do it is to take the timing chain covers off then change the tensioner.

[lilws6]

as long as you didn't hear any nasty rattling and then a good whack when it shut off the motor should still be good :) there should be timing marks on that motor. Look up and print off how to set the timing and reset it. probably more work than you wanted but it should still run when your done.

[brotherbenn83]

There are two chains, the second one runs the balance shafts and water pump. Were they both slack free?

[MY FYN 79]

I actually never pulled the side cover off if that's what is being referred to. I can see the other chain, but cant check it.

I pulled the top cover off again to see whats going on. The new tensioner is in and released, but if I turn the engine over the chain skips on the intake cam sprocket so I'm sure the problem is in there.

I'd have no problem dropping 150 or so on replacing all the timing components, but if its got bent valves and stuff that really throws a monkey wrench into it. Any way to test how well the cylinders seal when I cant even turn it over?

[brotherbenn83]

I actually never pulled the side cover off if that's what is being referred to. I can see the other chain, but cant check it.

I pulled the top cover off again to see whats going on. The new tensioner is in and released, but if I turn the engine over the chain skips on the intake cam sprocket so I'm sure the problem is in there.

I'd have no problem dropping 150 or so on replacing all the timing components, but if its got bent valves and stuff that really throws a monkey wrench into it. Any way to test how well the cylinders seal when I cant even turn it over?

Thread an airhose into the spark plug hole and pressurize with the valves closed.

[MY FYN 79]

I have a leakdown kit, just ended up having to pull the chain off and rotate everything by hand to get the valves closed. Wasn't able to do a compression or leakdown test because the chain kept skipping and couldn't get both sets of valves closed.

Final word- Its junk.

[brotherbenn83]

I have a leakdown kit, just ended up having to pull the chain off and rotate everything by hand to get the valves closed. Wasn't able to do a compression or leakdown test because the chain kept skipping and couldn't get both sets of valves closed.

Final word- Its junk.

If you want to sell the car let me know.

[MY FYN 79]

If you want to sell the car let me know.

I'm not gonna risk fixing the top end of this engine because of the cost. So if I would end up buying a different car, I'll put a different engine in this one before selling it. Even considering a 3400 swap from a clapped out low mileage Grand Am GT that's available.