Engine Break In Mishap

Ok been working on my motor swap making everything pretty painting brackets/engine/ engine bay frame/exhaust manifold was gonna post all the pics when done
Finally found tdc since balancer mark wasn't lining up
Got her started sounded great warmed up to break in cam @ 2k or little more varying little bit through out.
Well 10 mins later BOOM!! Steam everywhere. ..my read end cap blew off ..panic cleaned the engine and assessed damage engine still runs fine thank god. But wondering what went wrong I filled the block then radiator BUT forgot to take of cap when initially starting up so im thinking just air in the system..
Buying new rad tomorrow with me luck

HeavyChevy77 wrote:

ouch

Looks like a faulty radiator. Unless it overheated or something else that would cause too much pressure in the cooling system. I've had those aluminum/plastic radiators fail there before, but not at initial startup.

No overheating but maybe it cause I didn't remove the rad cap to purge air in the system?? Or a bad rad all I do know is that it scared the shit outta me when it happened.

As rule the last thing I would do is put on the radiator cap. Usually fill then run motor then check level while engine is

running and fill again. You def could have had lots of air in there to cause that problem. Sometime you even

have to burp them few times to get it out.

replace the cap for piece of mind as well.