Engine seized 2 miles after rebuild

I just finished rebuilding an engine for my 53 Merc. Had the new block magnafluxed - no cracks. Bored out to .60 over. Reused the pistons, rods, crank and cam. Had engine fully balanced. New rings, berings, and bushings. Fired it up last night and all was well. Took it out for a break-in run today and got about 2 miles and it seized. Oil pressure was 45 lbs at 30 mph. Temp was 170. Was running great until I came to a stop and then it just seized. Tried to turn it over by hand (2’ breaker bar on the front pulley bolt) with no luck. Drained the oil and nothing in the oil. Any suggestions....... before I pull the engine. <!-- / message -->

 

When you bore .060 you need .060 pistons.

 

nope, pull it. sucks, been there. although i got about 1000 miles on mine before it locked. sent it to a local machine shop. he found the bearing tolerances were to tight through out the engine and spun 2 rod bearings. the "reputable" place i got it from dodged my calls.

 

Yeah.... reusing the pistons was a big no-no.

 

What shineyside said.

 

The resused pistons were already .60

 

What did the rebuild involve?

 

Guarantee they arent .60

The way you said it we though you bored it out at rebuild.

 

You DEFINATELY need .060 over pistons if you did indeed bore the block .060.

BUT, that doesn't mean that is what locked up your engine. First, you need to make sure the engine is actually locked up. There are lots of other things that will keep an engine from turning over....flywheel bolts, torque converter/clutch failure, etc.

Maybe you could tell us more about your combination and the specifics of when it locked up and we might be able to get it figured out.

-Abone.

 

Is it possible the slugs are fine, but your crank and rod bearings too undersized?..including possibly the cam bearings ?Maybe all of it was too close in tollerance

 

Do both the upper and lower main inserts have oil holes in them? I have seen engines assembled in which only one insert is drilled for oil and needs to go in the block not the cap. Get it wrong and sure enough, a few miles later it stops.

 

Pull the plugs and see if it filled with water and hydroliced a cylinder.

 

Like others, I question you about your statements that the "new block"...."bored .060" over. Did YOU have it bored? Reading your words it sounds like you had the block bored .060" and then "REUSED the pistons". If that is the case, you have a basic serious problem. I am NOT trying to give you a hard time, but if this very basic error was made, it's a good bet that the rest of the engine specs/assembly are also incorrect. Please give us more information about the rebuild with more specific details.

 

What he said.

You did say YOU bored it .060 over, and then you said you reused the same pistons. Was it already bored??

 

Rings might be too tightly gapped, or possibly an incorrect bearing insert was installed.

Did you use different fasteners in the exhaust manifolds? If using bolts, and the bolts are too long, you can possibly deform the cylinder wall(s) when they're tightened. It doesn't take much to lead to a seizure. Front & rear cylinders are most susceptible.

 

By way of more detail. My old engine was already bored out to .60 +. I had a crack between an exhaust valve and the cylinder so I decided to get a new block. Found the block and had it maganaflux to insure there were not cracks. Decided to use the pistons (.60), rods, crank and cam. Had new cam bearings pressed in, used new rings, rod bearings and main bearings. Had the engine balanced. Cleaned up the heads with a .008 cut. Resized the rods. Cut all seats. Installed exhaust seats. New pin bushings. Polish crank. Drilled intake for adjustable lifters. New adjustable lifters.ffice
Stock engine except for the over bore with an automatic trans. I was test driving it up and down the road in form of the house. Did three laps (about 6 blocks)...came to a stop to turn around and the engine stopped and will not turn over.<O</O

 

how did it stop? sputter? sneeze? loud bang dead stop? Did you crap your pants?

 

No pants change was necessary.....came to a stop and it just stopped...no loud bang, no sputter, more like it just stalled. Tried to restart the starter engaged but would not turn it over. Engine is now totally cold and still locked.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
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If it just slowed down and locked up, my guess is the main bearings...my 400 Pontiac went from a 2k rpm rev to dead stop in a split second...I took the pan off and found strands of bearing material squirting out of the main caps...

 

When you tear it down , let us know what it is

 

Have you pulled the plugs and tried to turn it over?

 

I would disconnect the torque converter from the flywheel first...................after what Henry said...............

 

Lets put decimals in perspective for you. You still insisting .60 makes me wonder about the bearing tolerances.

 

what the heck are you talking about?

 

Read the thread bud.

 

.060 not .60

 

Yes I've been reading this thread. What does .060 cylinder overbore have to do with bearing clearances?

 

oh I get it, you are nitpicking on his use of .60 ...crist sakes.

 

Guarantee they arent .60

The way you said it we though you bored it out at rebuild.[/QUOTE]

 

Oil pump? Oil pump pick up? It takes bout 2 miles on assembly lube at low speeds before the bearing melt. Bet the oil was clean and cold.