2005 Yukon Denali xl no crank loud thump

[Brisolle]

Hi all:
I have a head scratcher on a new to me Denali and hope one of you guys can point me in the right direction. My 05 has the LQ4. It was throwing p0300, random cylinder misfire. I replaced spark plugs, spark plug wires and starter. I also replaced three brake lines due to leaks(not related to this issue but…). It cranked and started before I changed the plugs. It cranked and started with a very rough idle after the new plugs and wires.

Checked for codes p0300 again. Tried to start it again and heard a loud thump. It would not crank after that so I bought and installed an Autozone starter. Same thing, no crank and loud thump every time. It seems like it wants to cranks but something is stopping the flywheel. I have a brand new battery. I checked fuses and starter relays on fuse block by the battery. All work fine. I manually turned the crank pulley clockwise using a wrench and it turns about 1/4 to a 1/2 turn with the plugs in. I had car towed to shop and am going there this afternoon to check on it but would like to hear what you guys think.

 

[ks03]

Why was the starter being changed?

 

[Brisolle]

Rookie mistake. I did not test it and made an ass out of me.

 

[ks03]

Was it replaced originally at the same time as plugs and wires, or only after plugs and wires?

 

[Brisolle]

it was replaced one day after plugs and wires.

 

[Doubeleive]

bench test your original starter, if it is good put it back in, otherwise you might need to adjust the replacement starter position with a shim, your description sounds like the starter is jamming up on the flywheel. as for the rough running after plug and wire replacement re-check your work make sure you didn't accidentally smack a plug and mess up the gap.

 

[OR VietVet]

I would be worried about, I worry a lot, a cracked or damaged flex plate and maybe the P0300 code is related to coolant in the cylinders and hydraulic lock if enough coolant is in there when cranking. Pull all plugs and crank over and see if you see any coolant shoot out. Maybe put a clean fresh towel just below at at the plug hole and see if spits anything on the towel. Run a compression test when plugs are all out.

 

[Brisolle]

Hi all:
I have a head scratcher on a new to me Denali and hope one of you guys can point me in the right direction. My 05 has the LQ4. It was throwing p0300, random cylinder misfire. I replaced spark plugs, spark plug wires and starter. I also replaced three brake lines due to leaks(not related to this issue but…). It cranked and started before I changed the plugs. It cranked and started with a very rough idle after the new plugs and wires.

Checked for codes p0300 again. Tried to start it again and heard a loud thump. It would not crank after that so I bought and installed an Autozone starter. Same thing, no crank and loud thump every time. It seems like it wants to cranks but something is stopping the flywheel. I have a brand new battery. I checked fuses and starter relays on fuse block by the battery. All work fine. I manually turned the crank pulley clockwise using a wrench and it turns about 1/4 to a 1/2 turn with the plugs in. I had car towed to shop and am going there this afternoon to check on it but would like to hear what you guys think.

Will post details on what happens at the shop. I should have the truck back tomorrow or Friday. Will keep you guys posted. Hopefully won’t have to start an engine replacement thread. Thank you all for the generosity of your time and wisdom to help out a stranger. Siempre Fi.

 

[Brisolle]

Damn auto correct. Siempre = Semper

 

[OR VietVet]

You do know you are averaging less than one post per year, right? Sit back and relax. You must be worn out!!!!!