Blowing out freeze out plug after start up

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ahlberg

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Hi All,
My sons and their friends and a machine shop rebuilt my 273 for me as a surprise gift. After about 8 minutes the engine blows the left back cylinder head freeze out plug, twice. I.m sure an overpressure situation.
The thermostat is out, top radiator hose hot, bottom cold. Water in the oil. Any ideas what could have gone wrong during the rebuild. Pulled the left head, no smoking gun. Suspect / troubleshooting ???
I would appreciate your expert opinions big time. Thank you,
Glenn
 
This is just a guess but...

You have a blockage in your cooling system, maybe a stuck thermostat. Then the engine over heated and you blew a head gasket or cracked a head. Where is your temp sensor located? Where you watching the temp during the break in? If your temp didnt go up then your temp sensor is broken or down stream of the coolant blockage, probably thermostat.

Since there is water in the oil, at a minumum the head gaskets need to be changed.

My guess, you got a cracked head, but it is just that a guess. and probably a stuck thermostat that cooked your block. If you popped a freeze plug things must have got pretty hot and caused some damage.

Have the heads checked for cracks.

Sorry dude
 
The thermostat is out. Best way to check for cracked heads ?????
 
Take em to a machine shop, its cheap. But if you can see the cracks your in bad shape.

Seems like there is a restriction somewhere in the coolant system that caused the whole issue. do you have compressed air by the car
 
I,m not to familiar with 273,s,but sounds like one of the internal plugs(removed at time of cleaning for rebuild)wasn,t put back in when assembled.Most engine places would magnaflux heads when rebuilding an engine.I believe you can check for the plug by pulling the dizzy?This is just a guess,but could be your problem.Others with more knowledge about the 273 will chime in.Hey ToolManMike!!!!Some help needed here!LOL
 
The 273 is just like all of the other LA smallblocks. Maybe a Magnum head gasket was used & blocked a water passage to the head? Just a wild guess as I know there are some differences there but I would think the wrong gasket would also block an oil passage & starve the top end for oil so I don't know if there's a chance they would have done this.
 
Water in the oil is not a good thing. Hopefully not for only a few minutes. I would suspect the wrong head gasket but a cracked head is a definite possibility. Coolant pressure is only around 15 pounds and unless the freeze plug was installed incorrectly it shouldn't blow out. It sounds like you're getting compression into the cooling system causing the plug blowout and the coolant in the oil. You should take it out and take it apart and look closely at the head gaskets and have the heads checked for cracks. Good luck and keep us posted.
toolman
 
Thanks guys for all your suggestions !! I'm going to bring the heads and gaskets to the machine shop tomorrow. I'll let you know what happens
 
Hi All,
We have pulled the heads. Head gaskets holes matching up where they should. P/N's correct. Well everything has gone to a dead end. I blew air through the heads and block. My 2 other partners said they feel there is better flow through block and head. Hopefully dislaged something. Changed oil and filter. Decided to spend the 100 bucks on the gasket set and time. The alternative sucks.
The person that did the machine work said we overheated it and I obviously did not know what I was doing. Not a good selling point for me to bring parts back to him. We all feel it got hot but not enough to do damage.
Should have know the story next weekend, hope to drive it to his shop tell him everything was good, he needs to take a class on customer service, and do a big old burn out up the street........
 
Nope, we pressure checked it the best we could Everything seems good enough to give it another shot. We have a bit of confidence in this.if it doesent look good. In this economy, looking for a deal. Mopars at the strip 56 days away...........clocks ticking.
 
Could not afford bring it back to the machine shop. Decided to go for it and replace the head gaskets. During that time I bought a bunch of rubber plugs and plugged off the block and blew the block out with compressed air. The air flow seemed to get much better like it blew something out. Did the same with the heads. Reassembled everything, no freeze out plugs blowing out, no, overheating. I was/ am ecstatic. Dialed everything else in, engine runs great. I feel it was something restricting the block coolant flow or the heads. Lesson
learned, when things look real bad and expensive, take a chance......
 
Glad you got it figured out.Obviously your builder didn,t do a very good job of cleaning the heads and block when it was apart for rebuild.(blockage)
 
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