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360 Core Plug?

jumbreit

jumbreit

Well-Known Member
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Location
North Fond du Lac, WI
I have a hole in the bottom of my block, drivers side, rear, that looks like it could be from a missing core plug. I recently installed and put some antifreeze into the radiator after getting the engine together and I started to get a small amount dripping on the floor. I was about to pull the tranny to see if I had a leaking core plug and found this.

IMG_1901.jpg

Looking at my engine tear-down photos, it looks like this has been open since then. There's a corresponding plug in the front of the engine on the same side. I don't recall seeing any plugs for this in the ones I ordered.

DSC05499c.jpg

IMG_1901.jpg


DSC05499c.jpg
 
I may will be wrong on this but have always believed these to be casting holes used to lift the engine assembly will on the assembly line.
 
I hate to say this , but I think you have a crack in a water jacket . Those wholes are normally open . I don't remember , did you build this engine or did you send it to a machine shop ?
 
I rebuilt the block, sent the heads out. So does that mean I have to get a different block? Would a cooling system pressure test prove that this is the case?

I just figured it was closed since there's a similar thing in the front on the same side.
 
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Yes you can pressure check it . It might be kind of hard to see the crack . But I think you should anyways , just to be safe . How bad was it leaking ? Was it fully warmed up and under pressure ( Cap On ) or were you still in the process of warming it up and adding the coolant( Cap off ) ?
 
It's just a small drip. I had the radiator back off after running it this summer (see above video) and had just put the radiator back on and refilled it. I haven't run the engine yet and all I really did was spin the water pump.
 
I'm afraid that's not a good sign . If it's leaking now when the engine is cold with no pressure then it's going to leak even worse once you get it hot and build up pressure in the cooling system . I say if you can , Do a pressure check on it and try to see how deep the crack is in the whole and how bad it is .
 
Were it me, I believe the first thing I'd do would be to make absolutely sure that's where the liquid is coming from, assuming the photo of the block was taken during the rebuild. I'd wipe it clean, hoping enough coolant would be left for flour or talcum powder to stick to. If so, with close and patient observation, you might be able to see where the fluid is actually coming from. Capilllary attraction can cause liquids to creep uphill, defying the laws of gravity and fooling a person as to its origin. If the crack is in the hole itself, you might try cleaning it thoroughly and using epoxy.
 
Yeah, that's what I was thinking, that I should make sure the fluid is coming from that hole, and not a leaking freeze plug hiding in the bellhousing.
 
Possible , that would be nice if it was but the closest freeze plug to that area is about three quarters of the way up towards the middle in back of the motor . But like I said anything is possible . That's why you should do a pressure test and know for sure .
 
I pulled the thermostat and did a pressure test today and everything looks good for the most part. The manual says 14-18psi. I ended up leaving it at 16psi for about an hour and it dropped to about 14 over that period of time. The drip through that rear hole stayed steady and didn't really seem to increase. I did wad up a piece of towel and stuffed it in there, high enough so that I could be sure of no wicking. The area around the hole remained dry until the some antifreeze started to seep through the towel. There were no other leaks throughout that time.

Any thoughts?
 
Sounds like to me that you have an external crack in that area . The only things I could suggest is #1 If the crack is far enough up in the hole then you could try and plug it with either a sleeve of some sorts or find a freeze plug that would fit there . #2 Get another 360 block and start all over again . Sorry I don't have any other suggestions at this time .
 
bear said:
Sounds like to me that you have an external crack in that area . The only things I could suggest is #1 If the crack is far enough up in the hole then you could try and plug it with either a sleeve of some sorts or find a freeze plug that would fit there . #2 Get another 360 block and start all over again . Sorry I don't have any other suggestions at this time .
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If the leak is as small as it appears to be, can't I just drive it until it totally pukes and I get another block?
 
Run a wire hone threw it to clean it out and fill with epoxy. Crack sealed and hole filled.
 
jumbreit said:
If the leak is as small as it appears to be, can't I just drive it until it totally pukes and I get another block?
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Really ? After all this work your thinking " Run it till it blows" ? So far you've run the motor for what , about ten minutes or so ? What do you think is going to happen when the truck is all together and your out in nicer weather or sitting in traffic and the block is getting warmer and warmer and building up more and more pressure ? Well ? I say it's your truck and it's your call . Either run it till it blows or spend about 30 minutes and try and fix it . Even if you call it a temporary fix . You could even combine my idea and "7Mopar's" idea ( wire hone the hole , fill the area with epoxy or JB weld , and then tap in a small freeze plug on top of that ) and really have a better chance of sealing it .
 
I just meant that if I couldn't patch the crack and the only other option was to replace the block, is could I drive it until the leak became unmanageable. Not till the engine 'blew'.

I do like the idea of plugging the hole. Would I want to go in and drain it occasionally? I didn't know if allowing that area to fill with coolant that didn't circulate was okay.
 
Well if you drive it constantly leaking and running hot or over heating then your going to blow it up . And you "know" when that happens it won't be at a good time . That is "if" there is a good time . So I say , Hone it out like "7Mopar" said real good with a wire hone hooked up to your drill . Put some epoxy up in there all over in the sides of the hole and tap a freeze plug in the end . Once everything has sat for a while and dried then throw some anti freeze in the motor and see what you have . Personally I think it's worth a shot . And no you won't have to drain it afterwards , if this works . It will be just a pocket beside the water jacket and hopefully if the epoxy takes then there won't be any water in there anyways . The freeze plug will be added security to keep everything high and dry .
 
85Dodge360-4BBL said:
360 blocks are easy to find, and still relatively cheap...... I would get another block......
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So you don't think about $20 or less in parts and tools and about a half hour of his time is worth it to try and fix this motor ? Even if we call it a temporary fix ? And I only say temporary because some of my temporary fix's people have gotten ten years or more out of . But to me that's what they were supposed to be at the time .
 
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