Help! Car ran for 4 min after timing belt replacement and now won't start.

[petrified.rabbit]

Don't want to hijack the thread, but I'm not understanding this. I have no experience with something like this actually happening, but would expect the engine to just start misfiring badly and quickly shut down because of it. Why would the valves get bent if it was just the balancer not in sync, but everything with the timing belt was still ok, maintaining proper valve/piston movement? What am I not understanding about this?

The keyway would be holding the timing gear in place, not the balancer. So if the keyway broke, the timing belt would not be turning in time with the crank = bent valves.

...I was thinking, does the aveo have a knock sensor? Is it possible that the knock sensor could be sending a signal to cut spark or fuel? The only reason I wonder is becuase when I haven't been cranking on the car for a while, when I go to start it, the car catches for a few revs before it seems to loose the urge to turn over. It's almost like some protective circuit is kicking in...

it does have an oil pressure switch on the back of the engine near the timing cover, this if oil pressure is not present it cuts spark (i believe).

about the backfiring on starting fluid, i think you need to do a cylinder leak down test, if you have a better compression tester that has the airline style fitting in it, then you can cheat and use that, put a cylinder at top dead center, put the line onto it and pump in some air (not 90lbs, start with just a little). listen to the intake, and exhaust for air movement, if the cylinder is sealed, then you should not hear anything. Where did you get the head and valves? 140 psi compression is good, but you should not be able to backfire.

the only things i can think of at this point are archaic at best, but could work, like pulling the plug and cranking the engine so see it gas blows out of the cylinder, pulling plugs and testing them against the block for spark, etc. Not that you haven't done those test proper. But sometimes the wrong way shows more. Im still leaning toward no gas, personally.

[Player1111]

If you can get a scan tool you can check for codes. I would be interested to see if there is a cam/crank correlation issue in spite of the new parts - electrical parts have a high failure rate right out of the box. The backfire out of the intake hints to an ignition timing issue, even if it only did it once. Bad or partially failed cam or crank sensors could (theoretically) scatter your spark.

Yeah, I'm with you on bad electronics right out of the box. However, what are the chances that the parts on the car were bad AND the new parts are bad as well? I've tried cranking the car with the cam and/or crankshaft sensors disconnected and the ignition doesn't spark at all.

[Player1111]

The keyway would be holding the timing gear in place, not the balancer. So if the keyway broke, the timing belt would not be turning in time with the crank = bent valves.




it does have an oil pressure switch on the back of the engine near the timing cover, this if oil pressure is not present it cuts spark (i believe).

about the backfiring on starting fluid, i think you need to do a cylinder leak down test, if you have a better compression tester that has the airline style fitting in it, then you can cheat and use that, put a cylinder at top dead center, put the line onto it and pump in some air (not 90lbs, start with just a little). listen to the intake, and exhaust for air movement, if the cylinder is sealed, then you should not hear anything. Where did you get the head and valves? 140 psi compression is good, but you should not be able to backfire.

the only things i can think of at this point are archaic at best, but could work, like pulling the plug and cranking the engine so see it gas blows out of the cylinder, pulling plugs and testing them against the block for spark, etc. Not that you haven't done those test proper. But sometimes the wrong way shows more. Im still leaning toward no gas, personally.

I bought the cylinder head from Odessa cylinder head off of their ebay store.
GM Chevy Aveo 1 6 DOHC Cylinder Head vals Springs Only | eBay

The backfire happened after I had sprayed quite a bit of starter fluid into it. The same thing happened when I pulled the injector manifold off the car so I could see if the injectors were firing any fuel. They are--but the car backfired at me again. Can't keep making fireballs under the hood. Things are getting scary.

[petrified.rabbit]

so, 140 compression. gas. and spark. should be running.


when you crank it over what does it do? is it a fast crank that tries to catch, a slow crank, a faster than normal crank?

i'm still concerned about the ability it has to backfire. that means there is spark while the valve is still open to the intake. which would point to timing being off.

[avguy]

The keyway would be holding the timing gear in place, not the balancer. So if the keyway broke, the timing belt would not be turning in time with the crank = bent valves.

That's not the keyway I was talking about. The keyway I'm referring to is the one on the back of the balancer, as seen in the Ebay ad below. If the metal tab fitting into that keyway somehow broke off, the balancer would spin independently from the timing loop, even though everything in the loop itself is still ok. Not saying that's at all likely to happen, but it's at least physically possible.
But I do agree that this sounds like a timing problem. Tho OP insists that the timing marks are on, so that's why I was asing about this remote possibility.
Auto 7 621 0062 Harmonic Balancer | eBay

[Player1111]

so, 140 compression. gas. and spark. should be running.


when you crank it over what does it do? is it a fast crank that tries to catch, a slow crank, a faster than normal crank?

i'm still concerned about the ability it has to backfire. that means there is spark while the valve is still open to the intake. which would point to timing being off.

When I first start cranking it, the first few revolutions always sounds like it's going to start. The tach moves off of the zero RPM mark. Then, the engine just goes lifeless. The car will crank and crank at normal speed but not do anything. If I keep cranking, for like 15 or 20 seconds, the car will start catching sporadically, with RPMs are faster than a normal crank.

[Player1111]

That's not the keyway I was talking about. The keyway I'm referring to is the one on the back of the balancer, as seen in the Ebay ad below. If the metal tab fitting into that keyway somehow broke off, the balancer would spin independently from the timing loop, even though everything in the loop itself is still ok. Not saying that's at all likely to happen, but it's at least physically possible.
But I do agree that this sounds like a timing problem. Tho OP insists that the timing marks are on, so that's why I was asing about this remote possibility.
Auto 7 621 0062 Harmonic Balancer | eBay

OK, so even if this balancer was broken, why would that affect starting of the engine? The alternator, AC compressor and PS pump are hooked up to this pulley (from memory, not looking at the car right now). I would think that you would be able to start the car with no belt on this pulley.

[avguy]

OK, so even if this balancer was broken, why would that affect starting of the engine? The alternator, AC compressor and PS pump are hooked up to this pulley (from memory, not looking at the car right now). I would think that you would be able to start the car with no belt on this pulley.

Well frankly I don't know if the balancer not turning in synch with the rest of the timing loop would have that type of an effect. I only mentioned it as something for you to check, because it sounds like you have already done everything else related to the timing. With all the marks in line, all the sensors replaced, and good compression, it doesn't seem possible for your to have a timing problem. But OTOH, that backfiring just doesn't seem like it could be anything else but a timing problem. You have a really weird thing going on there. When you finally figure it out, please post the outcome and answer to what's going on with your Aveo - inquiring minds want to know!

[Olethro]

OK, so even if this balancer was broken, why would that affect starting of the engine? The alternator, AC compressor and PS pump are hooked up to this pulley (from memory, not looking at the car right now). I would think that you would be able to start the car with no belt on this pulley.

Install an old fashioned vacuum gage on a fitting that has manifold vacuum and check cranking vacuum value. If the gage shows 5-7 inches of vacuum gradually dropping to zero, or shows zero straight up, you may have a clogged exhaust system. You can try to start the engine by disconnecting the exhaust pipe at the manifold and letting it hang loose. Always have a fire extinguisher at hand, just in case! Remember that if you do not have a good exhaust cycle, you will not have a good intake cycle as well. Let us know what resolved the issue.

[Player1111]

Well, problem solved.....

Two weeks ago I got a code reader from a friend and hooked it up to try to diagnose any problems. The reader came up with a crank angle sensor problem, so I replaced it with the original--the code went away. It would also come up with other problems intermittently, ignition bank A not firing, ECU error, etc...but nothing that would stay once I reset the code from the ECU. I decided to pull off the timing belt cover and look at the crankshaft/camshaft position one more time. I cranked the car over for a minute or so and then the timing belt slipped off. Talk about an oh s**t moment!

I pulled the head, and sure enough, two of the intake valves were bent. I crafted up valve puller out of some steel that I had sitting around the house, pulled the bent valves and replaced them. I bought a new head gasket and reassembled the car this weekend. During reassembly, I noticed that the little studs on the camshaft which act as a key for the cam gears had came off with the cam gears--i.e. they would let the gears rotate without rotating the camshaft. I put locktite retaining compound (680) on the studs and gently tapped them back into the camshaft with a hammer.

Went to crank up the car and sure enough, it fired right up! Let it run for 15 minutes or so in the garage before daring to take it out and drive it around the block. Seems to work fine. There's a bit of valve train noise (i.e. you can hear the valve lifters clicking / tapping) but I gather from other threads on this forum that it might be normal or might go away with time. You really can only hear the noise when you are standing by the hood. Can't hear anything from inside the car. It's not one or two valves--from the frequency of the noise, all the cylinders are making the same noise. I replaced the oil with new 5W-30 when I first replaced the head.

Anyways, just wanted to post what I found. I've read though too many threads where people posted a problem and never followed up with what fixed it. I appreciate all the help/suggestions that I received from you guys.

Next up: Replacing and repainting the cracked front bumper. After that, the car should be good as new.