Mid 70's 360 motor mysterious water leak

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carguy47

carguy47

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OK. Having an issue with my latest project. The motor is a 1976-78 date code 360 SBM. When it is running, water/antifreeze if leaking out of the lower passenger side water pump bolt. I pulled and cleaned the bolt. Put thread tape and sealant on bolt and threads. STILL leaking severly.
What could this be?
Thanks FABO for any help.

leak.jpg
 
Thread tape could be your problem. Thread tape is not designed for bolts. It is designed for pipe threads. It needs the taper of pipe threads to seal. No taper, no seal.

If you have luck with sealing tape and bolts, you got lucky. Period.

Either the tape is stopping it from sealing, or the timing cover is cracked. You should use only silicone RVT to seal bolts. It works best.
 
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I would get another good bolt of the right length & even a slightly longer one for more thread engagement wont hurt & coat it with some viscous cement such as Permatex #2 in the toothpaste like tube or even the brush on Permatex #3 aviation cement which is a bit thinner has worked well
 
And get rid of the splitwasher. They make bellevilles that work excellent as secondary back-ups. Do not use as a primary cuz the coolant will be trapped in the passage and eventually corrode it up so bad it will be impossible to take it apart. You will have to cut it apart, destroying the T-cover and probably the pump too.
 
  1. Remove bolt
  2. Chase threads with a tap
  3. Spray out threads with brake cleaner or carb cleaner, something like that, so it's nice and clean
  4. get a new bolt from the hardware store, make sure it's the right length, more thread engagement is good as long as it doesn't bottom out
  5. Use thread sealer on the threads and the install the bolt. You can find thread sealer at the autoparts store or on Amazon along with many other places, there are several brands. There's even high temp thread sealer

AJ/FormS said:
And get rid of the splitwasher. They make bellevilles that work excellent as secondary back-ups. Do not use as a primary cuz the coolant will be trapped in the passage and eventually corrode it up so bad it will be impossible to take it apart. You will have to cut it apart, destroying the T-cover and probably the pump too.
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On a related note splitwashers don't do anything other than cause problems. I always remove them.
 
70DusterBob said:
No one mentioned it may be the timing chain gasket, or water pump gasket. Could be either one of these if the above don't work.
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^^^ agreed & also a too thick of the cork supplied gaskets on each end (from head/deck/intake milling) can hold the intake up just an inperceptable amt when it is bolted on, enough to cause one or both of the front head to intake gasket water port interfaces to leak slightly. If needing to go thinner I use silicone instead. EDIT & they (the cork ones) might not leak right away.
 
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70DusterBob said:
No one mentioned it may be the timing chain gasket, or water pump gasket. Could be either one of these if the above don't work.
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I didn't mention it, because if it was mine, I would pull the entire front of the engine apart and fix it RIGHT. Once and FOR ALL. So it would get new gaskets.
 
RustyRatRod said:
I didn't mention it, because if it was mine, I would pull the entire front of the engine apart and fix it RIGHT. Once and FOR ALL. So it would get new gaskets.
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Sorry Rusty, I was just saying that it could be "just" the gaskets when everyone was pointing out what else it could be. Didn't mean to offend you. If it were not the gaskets, and say he was using the wrong thread sealant, or too short a bolt, and he pulled the entire front end of the engine off, replaced the gaskets and went back with too short a bolt, not the right thread sealant, or what have you, it would still leak. Everyone's input is valid and important. I just mentioned the gaskets because mine happened to leak right there before and I had to pull the entire front of the engine off and replace all the gaskets too. So I know what you mean. I just mentioned it because no one else had that's all.
 
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Wasn't offended at all. Didn't mean it like that. I simply meant that I didn't mention gaskets because I took them for granted, because my engine would come apart there, to assure the repair 100%. That's all.

70DusterBob said:
Sorry Rusty, I was just saying that it could be "just" the gaskets when everyone was pointing out what else it could be. Didn't mean to offend you. If it were not the gaskets, and say he was using the wrong thread sealant, or too short a bolt, and he pulled the entire front end of the engine off, replaced the gaskets and went back with too short a bolt, not the right thread sealant, or what have you, it would still leak. Everyone's input is valid and important. I just mentioned the gaskets because mine happened to leak right there before and I had to pull the entire front of the engine off and replace all the gaskets too. So I know what you mean. I just mentioned it because no one else had that's all.
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You know how we all learn from our mistakes! This happened to me about 20 years ago when I had just started driving the Barracuda. It has a 340 and it was leaking slowly from somewhere around the same place; couldn't tell exactly from where. So like RRR said, I took it all apart to fix it right. When it was all back together, I poured the antifreeze in nd it just gushed out from the bottom of the water pump. After taking it all apart again, I saw that somehow the WP gasket got a fold, or crimp in it and left a nice little hole. That was when I learned to double check all gasket alignments one last time before mating pieces. I can laugh about it now, but it wasn't too funny then.
 
RustyRatRod said:
Wasn't offended at all. Didn't mean it like that. I simply meant that I didn't mention gaskets because I took them for granted, because my engine would come apart there, to assure the repair 100%. That's all.
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Oh, I have always been told that all caps meant yelling in text online. To emphasize something I will "Put Quotes" and only capitalize the first letter. Seems to get the point across well enough, and people don't think I am yelling anymore, lol!
 
70DusterBob said:
Oh, I have always been told that all caps meant yelling in text online. To emphasize something I will "Put Quotes" and only capitalize the first letter. Seems to get the point across well enough, and people don't think I am yelling anymore, lol!
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Yeah well, everybody does it different. lol
 
harrisonm said:
You know how we all learn from our mistakes! This happened to me about 20 years ago when I had just started driving the Barracuda. It has a 340 and it was leaking slowly from somewhere around the same place; couldn't tell exactly from where. So like RRR said, I took it all apart to fix it right. When it was all back together, I poured the antifreeze in nd it just gushed out from the bottom of the water pump. After taking it all apart again, I saw that somehow the WP gasket got a fold, or crimp in it and left a nice little hole. That was when I learned to double check all gasket alignments one last time before mating pieces. I can laugh about it now, but it wasn't too funny then.
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Man oh man. Frustrating is the word for that!! I have to replace the timing chain soon, I will be double sure to check all gasket alignments and that they haven't folded, or what have you before I bolt everything up tight. Thanks for the Word of Warning.
 
Every time i replace or adjust a v belt i dread seeing the leak. Twice i moved a bolt to adjust a belt, and had to do the gaskets. Im thinking better gasket adhesive next time and anti sieze to coat the bolts,also seals bolt threads.
 
Tooljunkie said:
Every time i replace or adjust a v belt i dread seeing the leak. Twice i moved a bolt to adjust a belt, and had to do the gaskets. Im thinking better gasket adhesive next time and anti sieze to coat the bolts,also seals bolt threads.
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Another option is to use long studs in the holes that go all the way through. That way, you are not disturbing the stud, but only breaking the nut loose. Just a thought.
 
RRR,thats a great idea, but i havent seen studs that long in my travels,t-rod is unacceptable.
Guess long grade 8 bolts and cut head off and thread.
 
Tooljunkie said:
RRR,thats a great idea, but i havent seen studs that long in my travels,t-rod is unacceptable.
Guess long grade 8 bolts and cut head off and thread.
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I'm not sure, but I know a manager of a bolt ware house that I can ask about finding a long stud like that, but yeah, that would be great. Do you suppose using the red thread lock would be required, or should blue work?
 
Could be the gasket but that bolt goes into the water jacket apparent. Mine leaks every time I loosen the bolt to tighten my a/c belt.
 
I'm sorry but I don't get all the hoopla about these bolts leaking. Since 1970 I have almost never been without an SBM, and I can not remember ever having trouble with leakage at these bolts. Maybe it has something to do with the 7# caps that I almost always run............ They make pretty good block drains tho........................ I mean to open the ones Ma gave us, are a real pita to remove,in frame.
 
Hey Carguy47,

Had the same problem with my 340. As some of the other's noted, I just picked up a new, slightly longer bolt and hit the threads with red Permatex. Let it sit/cure overnight before firing it up. Did the trick. Hope you get her sorted out easily and cheaply!

Pat
 
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