Please Help freeze plug popped out do to block freezing

[chrisperanio]

i have a 75 440 block in my race car i had drained the water out from the radiator before winter like i do every year this year i guess it did not completly drain and a freeze plug popped out on the passenger side front.....what are the chances that the block is damaged and how or what is the best way to thaw out the block, i currently have to heaters running to warm up the block....Please help.

 

[DetMatt1]

Hopefully the freeze plug did its job. In the future I think you should use antifreeze in the system or make sure you drain the block and the radiator. Warm it up like you are and pull the drain plugs on the sides of the block.

 

[jimynick]

You can buy aerosol two part crack detector spray if you really think you need to, but I'd put a new freeze plug (with a smear of sealant around it's edges) back in and when I re-filled the system with real coolant in it, I'd pressure test it via the rad and watch for either leaking down pressure or an actual leak from the block. You may have dodged a bullet, as mentioned. Good luck

 

[moparleo]

After you defrost the block, check the oil. It could also crack internally. Remember that they are misnamed freeze plug. They actually are core plugs. The block uses basically a 2 part mould when it is cast. It has an exterior mould and an interior mould, for the waterjackets, oil passages etc... When the block is cast, there has to be a way to drain the mould sand material from the internals of the block casting. That is what the holes are actually for. Heavy duty and racing applications will thread the holes and install actual threaded core plugs to stiffen the block.

Since you said that this is a race block. If you only use it for racing purposes, you could save the block by doing what the racers do. Install core plugs and then fill the block with a block filler material. Since most of the heat is generated in the upper cylinder area of the block, just fill the lower half of the block. This can help increase horsepower by stabilizing expansion and flexing of the lower block, helping to stiffen the lower cylinder and main bearing web area.

 

[DetMatt1]

Leo couldn't be more right, well said. I have seen one block recently that cracked from freezing in the valley under the intake about mid stroke. If you have to replace it you should hold out for an earlier block as they had higher nickle content and are stronger as a result but let's hope it doesn't come to that.

 

[Daves69]

....... I have seen one block recently that cracked from freezing in the valley under the intake about mid stroke. ......

Yep, that's where I've seen several cracked over the years. That's not to say freeze cracks are limited to that area. I'd pull the intake and valley pan off and check it.
IMO, when you're popping expansion plugs in winter you hope for the best but expect the worst.

 

[Kez]

Just thought I would share some good news on cracked blocks. My heart sank when they found a crack in the valley on my numbers matching engine block (71 Challenger RT). Did lots of searching, with horror stories on trying to weld repair. Then I found Lock N Stitch out of Turlock, CA. THey just finished the repair on my block today and it looks GREAT!! I will report back as the build goes, but it may be a while getting this car back together. But I am a happy guy (if a bit poorer).

 

[jimynick]

Was this fixed by the old drill and thread a hole, thread in a plug, cut it off and drill into it's side repeating the process until you do the whole crack method? If so, that's really old school machine shop work and I've seen it done a few times. It seems to work pretty well. Just don't overheat or freeze it again or all bets are off. Hopefully, they pressure checked it for you, too.

 

[Kez]

You are correct, they drill a series of holes (drilling every other one, so that all of them will overlap) - after installing the first set, they come back and drill between each one, then install another set of bolts, machine off, then use a needle descaler to pound it all together and get the casting look. The bolts they use have a specialized thread - they show it on their web site. Yeah, I had thought I better be careful not to reheat or freeze, but don't plan to let that happen!