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It appears I have a slow coolant leak coming through a crack in the block a couple of inches above where the oil pan bolts on.

It’s on a 67 318.

What would y’all do? Put some brand of crack repair in the radiator?

Something rotated this pic so you have to turn your head to the left to visualize it but this crack is just above a freeze plug and below the serial numbers.
Jeff

there are no coolant passages in the lower block( below the crank level), however, there are soft plugs higher up on the side of the block, rear of block also, these plugs sometimes leak with age. Check for your leak again, is it on the side , back or front.

Ditto Jeffc57. I had a similar leak with my 318. When a previous owner had the engine rebuilt, they did not paint the engine block. The expansion plug above the starter motor rusted through. A month or so later, another on the right side began to leak, also. I haven't had any issues since and I did spray some paint on the replacements and the remaining existing.

If that is your issue, it is a good opportunity to flush the cooling system, when you have the expansion plug removed.

67D100Pickup wrote: ↑

Thu May 25, 2023 4:59 pm

It appears I have a slow coolant leak coming through a crack in the block a couple of inches above where the oil pan bolts on.

It’s on a 67 318.

What would y’all do? Put some brand of crack repair in the oil?

Jeff

Got to ask. Why would you put crack repair in oil if its leaking coolant.

jeffc57 wrote: ↑

Thu May 25, 2023 5:58 pm

there are no coolant passages in the lower block( below the crank level), however, there are soft plugs higher up on the side of the block, rear of block also, these plugs sometimes leak with age. Check for your leak again, is it on the side , back or front.

I’ve added a pic to my original post. Does that help?

dodgeboykim wrote: ↑

Fri May 26, 2023 8:30 am

67D100Pickup wrote: ↑

Thu May 25, 2023 4:59 pm

It appears I have a slow coolant leak coming through a crack in the block a couple of inches above where the oil pan bolts on.

It’s on a 67 318.

What would y’all do? Put some brand of crack repair in the oil?

Jeff

Got to ask. Why would you put crack repair in oil if its leaking coolant.

Um, only a moron would try to stop a coolant leak by treating their oil. I was hoping to fix that before anyone noticed :-)

hate to say but there are only two fixes i know of are
cast iron welding ...have to remove engine ,take it apart .heat the block then an expert welder could possable weld it
the other is remove engine supper clean it ,remove the freeze out plugs and if you can get enough heat ,and clean can braze it
coolant sealant dose a better job clogging the rad and heater core then it does sealing cracks

67D100Pickup wrote: ↑

Fri May 26, 2023 9:32 am

jeffc57 wrote: ↑

Thu May 25, 2023 5:58 pm

there are no coolant passages in the lower block( below the crank level), however, there are soft plugs higher up on the side of the block, rear of block also, these plugs sometimes leak with age. Check for your leak again, is it on the side , back or front.

I’ve added a pic to my original post. Does that help?

YES, NO EASY FIX, sealer leak fix in the radiator may decrees some of leak, but it is not a real fix. As described pulling block and welding is the only real fix, or live with it and keep a eye in fluid levels, or engine replacement with another block.

This Uncle Tony video might be helpful:

Attempting To Repair A Freeze Cracked Big Block With A Cheap Flux Core Welder

https://www.youtube.com/watch?v=NWO0dgcKcZ4

67D100Pickup wrote: ↑

Thu May 25, 2023 4:59 pm

It appears I have a slow coolant leak coming through a crack in the block a couple of inches above where the oil pan bolts on.

It’s on a 67 318.

What would y’all do? Put some brand of crack repair in the radiator?

Something rotated this pic so you have to turn your head to the left to visualize it but this crack is just above a freeze plug and below the serial numbers.

image0.jpeg

Jeff

Do you have a ton of money in this engine?
I’m not sure how it works in Oklahoma but we have a hard time selling a 318 here in New York.

ha yeah ....thing i scraped a few back in the day .....but a lot of work to start fresh ...but the best way to go