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2005 cobalt start no start
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Hammer Time
Ultimate Carjunky
/ Moderator
Jun 20, 2021, 6:39 AM
Post #26 of 37
(1274 views)
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Re: 2005 cobalt start no start
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We have been approaching this all wrong by simply trying to guess at a solution. We are just spinning our wheels this way.
It's time to go back to basic "Crank, no start" diagnostics.
All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.
Every engine requires spark, fuel and compression to run. That's what we have to look for.
These are the basics that need to be tested and will give us the info required to isolate a cause.
1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.
2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.
3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.
Once you have determined which of these functions has dropped out,
you will know which system is having the problem.
You may also have to use a scan tool to examine sensor data to determine if the computer is getting correct data from all sensors.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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straightclaw
User
Jun 26, 2021, 3:32 AM
Post #27 of 37
(1211 views)
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Re: 2005 cobalt start no start
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Yesterday after testing all the ignition 1 circuit voltage and finding no short to ground. We pulled the valve cover and just as we had suspected timing chain. The chain drops about 3/4 of an inch between the two cam sprockets. Until we pull the cover we don't know for sure but we suspect it's jumped time. We'll pull the cover today and do a leak down test to see it the head needs to come off.
Thank you Tom looks like we may have had it from the start.
Also Hammer thank you for your help.
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Hammer Time
Ultimate Carjunky
/ Moderator
Jun 26, 2021, 3:57 AM
Post #28 of 37
(1205 views)
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Re: 2005 cobalt start no start
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We'll see. I still doubt that is your main problem.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jun 26, 2021, 4:38 AM
Post #29 of 37
(1201 views)
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Re: 2005 cobalt start no start
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3/4" drop think how high it could go too. Enough to clear sprockets? Trying to figure this out for you - for now HT and me.
It's a project was a given. I'm sure you care a lot that it someday isn't just a constant pest of a car. What else noticed when inside valve cover - anything? If there was even a hint of rust in there this could be lots more trouble. Wet rust now it's been run if still off check that perhaps scrape off anything that will and see if a magnet grabs it?
If run enough (time wise I guess) can you see 'pocking' on anything that should be smooth? Not good so hope not.
Lots of learning going on was freaked out from the get go "sat for 4 years" is tough,
Carry on,
Tom
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straightclaw
User
Jun 27, 2021, 3:22 AM
Post #30 of 37
(1175 views)
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Re: 2005 cobalt start no start
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We pulled the head today every intake valve is bent Not Bad but bent. I don't understand how the thing ran at all. They are about 1/8 inch open on one side. Could be more or less. Pistons seem fine. Just a few marks on them where the valve had hit. I have the head at my house now and will wait on parts to build it. We have no issues under that valve cover nothing a good cleaning can't fix. The car was kept under cover for the 4 years it sat. So other than this it seems to be in good shape. ill remove the cam's and valves today if I have time and see about getting the head surfaced. Thanks again Tom & Hammer and God Bless for taking the time to try to help someone. Ill be sure to keep posting until were complete. Thanks Again
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jun 27, 2021, 4:03 AM
Post #31 of 37
(1171 views)
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Re: 2005 cobalt start no start
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How is your Grandson doing with this so far? I feel the frustration.
If this takes some time now keep this > http://autoforums.carjunky.com/...h=-1;t=search_engine < so you can dig out this thread I/we would like to know how it came out.
At this point I would give up on this car but no fun in that, understood. If a ton of miles and a redone top end the older lower end can be an issue - oil burner or other surprises.
Now that you can see real well, what do sides of cylinder walls look like and showing my age the "ring ridge" up top? If excessive re-think this.
IDK what it would cost for a known, fresh exact match, used but low mile documented engine for you or are but might check.
That just cost wise not all the fun(?) this is being and some wild learning on this car.
Either way good luck with this part hope the rest of the car will behave,
Tom
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straightclaw
User
Jun 28, 2021, 3:38 AM
Post #33 of 37
(1137 views)
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Re: 2005 cobalt start no start
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Tom I appreciate you Sir the cylinder walls look fine and no ridge to speak of not for the miles anyhow. I don't know your age but years ago you would have seen more to be concerned about. Engineers have come a long way. Other than this issue with the timing this car is in excellent shape. That being the main reason for wanting to go ahead this way. Thanks Again and as always God Bless
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straightclaw
User
Jun 28, 2021, 3:54 AM
Post #34 of 37
(1133 views)
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Re: 2005 cobalt start no start
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Well Hammer the 1/8 is only a guesstimate may be less. As for how it ran I can't answer that . I'm still scratching my head over it. I really don't care at this point. Just glad to find what we suspected all along. In my 77 years I have seen a lot of weird things going on fooling with a circle track car. So nothing Suprises me about the function of engines. I'm a dummy when it comes to all the new electronics in cars today. But the basics are still the same. Fuel Compression Spark. But you have to have Time included in that. Here for Compression I just can't answer that one. Thaks Again Hammer and God Bless
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straightclaw
User
Jul 2, 2021, 4:08 AM
Post #35 of 37
(1087 views)
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Re: 2005 cobalt start no start
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My grandson has been going through classes for his License to sell Insurances. Having health issues he had to give up his CDL. So this is taking a bit to complete. Can anyone tell me what the two Allen head pipe plugs at the rear of the 2.2 Ecotec head are for. Thanks
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straightclaw
User
Jul 14, 2021, 10:28 AM
Post #36 of 37
(1037 views)
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Re: 2005 cobalt start no start
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Well this past Saturday I returned the Cylinder Head to my Grandson and he called me yesterday. Says it's running great and even still has the AC working. After sitting 4 years that's pretty cool if you ask me. The only problem he says he has now is an exhaust leak it may be the first section of pipe its a flex pipe and as old as it is could be. I just wanted to let those who tried helping me with this one last Thank You. God Bless
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 14, 2021, 10:39 AM
Post #37 of 37
(1033 views)
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Re: 2005 cobalt start no start
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Thanks for the follow-up and hope there's good life in this now.
Hate to say fix that flex pipe now but I just did. It's up front don't add an exhaust (monoxide) problem to a part that doesn't like flexing but what it's job is.
Do make sure motor mounts are good that stresses those out too.
Tap on muffler also see if it's full of flakes of rust even can look like new, it's water sitting in them doubt too much to do whole thing.
Cheers to hopefully a very happy grandchild with a car it's hard out there costs are way up,
Tom
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