bscott66

So I bought an 04 Denali (LQ4) as a rescue. It needed a trans, brake lines, gas tank, but it ran good. It sat for 3 months, then I made all the repairs and went to start it for the first time. It turned over once, maybe twice and came to a hard stop. I tried turning it over by hand and the engine turns normally in both directions but will not turn more than about 90% before it hits the same dead stop. Things I have checked: torque converter disconnected, removed belts, transmission bell housing unbolted and moved back from the engine, heads removed, timing cover removed. Still no change. The bottom end seems to rotate normally, the cam still moves freely. Any ideas on what the obstruction could be? When turned by hand, it makes a metallic clang, sounds like its coming from the rear of the engine. My next step is to pull the short block and drop the pan. I'm stumped.

Ls7colorado

iTrader: (3)

very curious to see the answer to this, bent rod is about all i can think of but it would have had to been hydro locked or something to do that upon startup.

G Atsma

Pull the heads. You WILL find the problem from what you just said.

bscott66

Damage in the bottom end is the likely culprit, just not sure how it happened.
Heads are off. cylinders look good.

brandon6.0

iTrader: (32)

Maybe a bent rod hitting bottom of piston. Maybe engine had water on cylinder and hydrolocked when u tried to start it. I always remove plugs on a engine tht set up and spin it over by hand. Just to be safe and blow out any water or trash in the cylinders.