I just repaired an engine in an '86 non-turbo that had had a fire. Finally got all the hoses back and replaced needed parts. On the first attempt at starting, the started turned it over for about a second and then it locked up. Started wouldn't turn it and so I tried rocking it back and forth very gently, but no go. Plugs out, no go. What could cause it to lock up? I don't THINK I dropped anything down into the intake, but... Any ideas would be appreciated.

 

is the battery fully charged? rebuilds tend to need all the help they can get to start.

also try pouring a little oil in the leading spark plug holes to help build compression.

and get the starter checked at autozone or something

 

Time for the ATF treatment.
If rocking it back & forth in 4th gear will not free it up, then something got into the chamber.

 

carbon lock if your talking about an old engine that has been sitting for a while

 

yep, carbon lock.. if the engine had sat for any decent amount of time with the plugs out of it or the manifolds off. pump a few ounces of MMO into the intake runners, leading plug holes and into the oil injector ports if you can, let it sit for a few hours and then continue rocking the motor to see if you are making any progress, if not then something probably got dropped into the intake while it was apart.

 

Thanks! You guys are not only smart..... you're very kind!

 

Speaking of MMO.... when I was in college in the 60's I worked at a foreign car repair shop in Santa Barbara owned by a Brit and he swore by Marvel Mystery Oil! I've used it off and on for the last 40 years in a number of machines, but I think I'll just go out and buy a gallon tomorrow! Thanks for your help!

 

i buy it by the gallon as well.

 

On a lot of fire engines I see rust and corrosion inside, even if the intake was sealed during the fire incident. If it's been sitting a while during these repairs, it could be seals that are rusted or stuck (carbon locked) in place. Try the lubrication and turning a few times daily for a few days...if it doesnt start moving on it's own, it'll have to come apart. Sometimes you can save them, sometimes not.