Need Help - Engine Seized ot Not? Please Read.

Hi everyone - I have searched many forums and can't find the answer I need. I recently purchased a 1994 Grand AM GT 3.1 L Automatic V6 for $500. 1 owner - said they parked it when they found water in the oil - Lower intake manifold gasket - right? So I pulled it home on a trailer and tore down the top end of the engine. Yep LIM gasket was bad - I went ahead and took of the heads and had them re-built and replaced head gasket, LIM gasket and so on. Pistons looked normal, shop said heads looked fine.

So I put it all back together and tried to start it - CLUNK - no movement. Tried new battery and starter - same thing. I took the plugs back out and tried turning the crank with a socket and breaker bar - no luck - would not move. I noticed the harmonic balancer was moving slightly when I tried to start the engine - so I put penetrating oil in the cylinders to soak overnight - next day kept bumping the starter and finally (after about 20 bumps) it started to move more - then finally turned over like normal - great right?...wrong- I put things back together and it started fine - next day started fine again - ran for about 20 mins - decided to take it for a test drive - drove about 500 feet to end of driveway. Car died - I restarted it fine - drove another 500 feet died again and now it's back to doing the same thing - clunk - engine not turning over - can't move crank.

I need help - trying to decide my options and next step(s).
1. Do I assume the engine is seized and junk it (I have about $1200 in the car total as of now).
2. If it is seized - why did it start and run 20 mins?
3. Is it better to fix (what is broken? I don't even know at this point).
4. Is it better to put in a used engine? How hard is it to pull an engine? I am comfortable tearing an engine down to remove the heads - but that is as far as I have gone.

This forum has given me excellent advice in the past and I look forward to everyone's ideas and guidance - thank you!

Coolant in the oil is not good, because you have no idea how long the coolant was mixing with the oil.......when that happens, you have potential bearing problems .....

1200 is a lot of money for a head job......you did the work yourself? No way there is 1200 in parts......

The horse is out of the barn so to speak......

You should have started the engine, to check it out.......should have dropped the oil and filter(don't circulate any more coolant), and replaced......then started the car before any work was done......you would have found the engine was seized before doing all this work.......

There are a ton of these motors in the boneyards.......could easily get a low mileage one for under $400......but there is no guarantee you would develop a lower intake problem down the road....

You bought a car that is over 20 years old.....1200 is more than the car is worth.......

I'm sure you had your reasons, and tried to fix it yourself........but unfortunately, you are now in a hole.......

You never mentioned the mileage or condition of the vehicle....vehicles this old, and if you live in a "Salt Zone" in the winter time, usually are rusted up badly underneath......suspension, brake lines, fuel lines, exhaust, etc.......

Plus, you had no idea what condition the tranny was in........

I'm sorry to bring you all this bad news......buying a used vehicle that runs, is a gamble, even if checked out.....buying something that doesn't even run, is just asking for trouble, unless of course, you have money to burn and plenty of time on your hands......but you are not the first person to have this happen to.....one of life's lessons.....

If still adamant on fixing this, a boneyard engine is the way to go......engine easily removed from the top with the hood removed.......just have to block up the transmission pan, to keep it level(it will want to drop when the engine is removed....and makes alignment better when reinstalling the engine......basically remove the flex plate bolts....tranny to block bolts(there is a hidden one you have to access from the passenger side with a long extension).......then disconnect harnesses, coolant lines and mounts, and then with an engine lift, remove the engine.....

Sorry you went through all that work without good results.....

I won't make any excuses - I know I took a gamble on a family member's car that was not running. $1200 is the total I have in the car (price of the car and all parts). $500 for the car, Parts (gaskets, new water pump, power steering pump, coolant, plugs, oil, etc.) $500, head job $180 for both heads. I did the work myself (not my first time replacing head gaskets).

I agree that I took a chance - but as the saying goes - no sense crying over spilt milk.

That being said - I value your and others opinion on if I should continue to chase the problem for install a junk yard engine. I have never pulled an engine so I need the groups input on if this is a recommended.

And ultimately I would like to know what is causing the engine to not turn - Piston against cylinder wall? Crank bearing? Cam bearing? The fact that it was "seized" then ran and now seized again is a puzzle. Thanks again.

A rod could have been bent if it was hydrolocked when the water got in the oil the first time. You may have just gotten lucky to get it to turn over when it did.

if something like the timing chain is broken it can seize the engine. might not even be the pistons seized. but without taking it apart you'll never know.

I'd pulled the oil pan and checked the mains and a couple rods. that give an idea of how long it was ran with coolant in the oil.