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Discussion Starter · #1 ·
I’ll do my best to describe the details as I recall. Just bought this 2005 Enviy with the 4.2. Needed the frame welded for inspection but I got a deal. Drive it around for 10 minutes, went to the title place and signed the papers. Then drive it for about 25 minutes to my brother-in-law’s garage. Was overheating but I didn’t know it as the gauges don’t all function. Lost power and misfired pretty badly and wouldn’t start once I got it parked. Next day it starts and he fixes the frame. No idea how it was running. I went to pick it up and it’s misfiring badly. Filled it with coolant/water to get it the 20 minutes home and made it (barely). Still has fluid boiling up and out of the cracked overflow tank when I got there so at least I know it wasn’t dry.
Checked for codes with my cheap tool. Got a P0301 cylinder 1 misfire. Changed only that plug. P0301 code. Swapped coil 1 and 2. P0300 code random misfire.
Swapped coil 2 to 3. Same. Swapped everything back to original spots (with the new plug in 1 and I’m still getting the P0300 misfire.

Biggest current concern: I cooked the engine and blew a head gasket. No evidence of coolant in oil. Plug 1 was dry, no coolant in that hole.

Any ideas of what to try next?
It’s acting very similar to my old 09 Traverse when the catalytic converter was clogged up. Anything that could have happened when it overheated to cause that? Worth a check?
 

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'05 Chevy TB EXT
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Nobody's answered you so far --- maybe 'cause you've created an almost monoparagraph and most people don't like to read between all those lines ... and some of the others are saddened by what has happened here ..... your choice ....



Let me help you sort this out into coherent sentences and questions ... .

I’ll do my best to describe the details as I recall.
Just bought this 2005 Enviy with the 4.2.
Needed the frame welded for inspection but I got a deal.
Drive it around for 10 minutes, went to the title place and signed the papers.
Then drive it for about 25 minutes to my brother-in-law’s garage.
Was overheating but I didn’t know it as the gauges don’t all function. THAT'S MISTAKE #1
Lost power and misfired pretty badly and wouldn’t start once I got it parked.
Next day it starts and he fixes the frame.
No idea how it was running. ME NEITHER --- BUT GO ON .....
I went to pick it up and it’s misfiring badly. SEEMS LIKE A LOGICAL HAPPENSTANCE SO FAR ....
Filled it with coolant/water to get it the 20 minutes home and made it (barely). THIS WAS A VERY BAD IDEA --- YOU'VE PROLLY GIVEN IT IT'S DEATH NOTICE BY NOW.
Still has fluid boiling up and out of the cracked overflow tank when I got there so at least I know it wasn’t dry. NO YOU HAVE NO REAL IDEA OF WHAT YOU ARE SAYING --- THIS COOLING SYSTEM DOES NOT WORK LIKE YOU THINK IT DOES.
IT ONLY MEANS THE COOLANT TANK HAD SOME COOLANT IN IT --- BEHIND THE RADIATOR CAP YOU HAD NO IDEA!
Checked for codes with my cheap tool. FROM THIS POINT ON, YOU'LL NEED A REALLY GOOD BI-DIRECTIONAL SCANNER THAT CAN 'SEE' REAL TIME FUNCTIONS.
Got a P0301 cylinder 1 misfire.
Changed only that plug. P0301 DOES NOT MEAN A BAD PLUG IN ANY CYLINDER, LET ALONE #1.
P0301 code.
Swapped coil 1 and 2.
P0300 code random misfire. P0300 IS A SYSTEMIC CODE THAT NEVER REALLY MEANS ANY OF THE PLUGS OR INJECTORS ARE AT FAULT. IT MEANS THERE'S A LOT MORE DIAGNOSIS REQUIRED TO FIND OUT WHY THE P0300 POPS UP.
Swapped coil 2 to 3. WASTED MOTIONS AND LOST TIME.
Same. TOLD YOU SO!
Swapped everything back to original spots (with the new plug in 1 and I’m still getting the P0300 misfire. SURPRIZED? NOT ME!
Biggest current concern: I cooked the engine and blew a head gasket. YES YOU DID.

No evidence of coolant in oil. THAT'S NOT WHERE IT'LL GO UNTIL THE VERY END.

Plug 1 was dry, no coolant in that hole. DON'T LET THIS ALLOW YOU TO THINK #1 IS OK --- DON'T DRAW TO A WRONG CONCLUSION WITH JUST ONE SAMPLE!

It's time to fess up to the truth --- you've damaged the head and/or gasket and all you can do is remove the head and send it out to re-machine after it gets dye-checked for cracks.

Be prepared for lots of negative cash flow --- out of your pocket.
 

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Discussion Starter · #3 ·
Apologies for the run on paragraph.

I’m a backyard mechanic at best and I’m just trying to get this runnable. I’m aware I don’t know a lot, which I why I came here to ask questions.

I appreciate your feedback. Is there anything else I might try? Care to address the catalytic converters possibility? I’d hate to waste time, but I’d rather “exhaust” some of that before throwing more money at it.
 

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'05 Chevy TB EXT
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Lessee .............. uhm ...............................

You had to get some structural repairs from severe rust?

HOW severe?
Bad enough that it won't pass inspection next time?
Will you have to patch more frame in the near future?
Is this rust-chasing gonna pencil-out at a decent price point .... acceptable ........ or a lot of money?

I ask because repairing these engines is never cheap and since the frame is of questionable integrity --- well ... you can see my point ... right?
 

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2003 chevy trailblazer_ltz
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Does the cooling fan engage when the engine got hot?
Does the cooling system hold pressure when pumped-up using a parts-store-rental pressure tester?
How old is the thermostat assembly?
How old is the radiator? Any obvious scale visible when the rad cap is off?
How old is the A/C condenser? Plugged with dirt/mud/cardboard/sparrows? Fins folded-over?
 

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'05 Chevy TB EXT
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OK ... when are you gonna start ripping the head off?

That's your next move.

I'd stop diagnosing at this point since it's kinda-fer sure obvious .......

@ Shurkey:

Does the cooling system hold pressure when pumped-up using a parts-store-rental pressure tester?
Any obvious scale visible when the rad cap is off?
There is no radiator cap on my '05 TB 4.2 radiator --- just the radiator surge tank has one ... but ...

The OP stated the surge tank was cracked so I doubt he can pressure test anything at all.

I'm pretty sure since there's no actual radiator cap on the radiator tank .........
......................... viewing the interior is nigh-on to impossible without disassembling the radiator itself.​
 
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