Coolant leak, drivers side lower timing cover?

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dano

dano

Evil Handy Man
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Getting ready to fire the 340, threw some new antifreeze in and after several days sitting (no run time at all) I have a leak at one of the two lower most bolts on the drivers side of the timing cover. I have not take in apart yet but looking at pictures it looks like the very bottom one by the pan is blind and the one above it looks to go into the water jacket? I have yet to see in the pan has coolant in it, the dip stick is dry (I have not put oil in it).

I had this area apart to install my CVF power steering brackets so I may just need to remove, clean and seal the thread(s). There is no coolant leaking above this point that I can tell.

FYI motor is fresh, un-fired with new core plugs done by the machine shop.
 
Almost all of them go through to coolant. If it’s just the bolt leaking you can drain the coolant and seal the threads on the bolt.

If you get any water in the oil it’s probably a sign the timing cover seal has to be redone. And trying to seal the bolt without draining the coolant is a great way to end up changing your oil too.
 
Drained it last night as soon as I found it. $70 in new antifreeze wasn't going to go on the floor, plus its not the nicest stuff for the environment. The leak is very slow. I sealed all the upper long bolts that go through the water pump. Its a really slow leak. I'm going to pull the pan plug to be sure there isn't any inside in case it's a larger issue.
 
IIRC, the 2nd from the bottom for sure goes into the cooling jacket. That is the spot, where if a too-long bolt is installed, it proceeds into contact with the #1 cylinder wall and cracks it.
 
Just remove the bolt(s) one by one around the leak and teflon them. If it still leaks...
then proceed . 15psi of coolant will make a small leak big.
 
nm9stheham said:
IIRC, the 2nd from the bottom for sure goes into the cooling jacket. That is the spot, where if a too-long bolt is installed, it proceeds into contact with the #1 cylinder wall and cracks it.
Click to expand...

Good to know. Hopefully that is not the case or my block is now scrap...

I do recall it tightening up the PS mount just fine and not feeling like I had to overcome some friction to get it tight. But it probably doesn't take much to puncture cast iron.
 
66jim said:
Just remove the bolt(s) one by one around the leak and teflon them. If it still leaks...
then proceed . 15psi of coolant will make a small leak big.
Click to expand...

As of yesterday is was about 2 weeks of head pressure. I might have lost a 1/2 pint of coolant.
 
For sealing those bolt threads into coolant passages, I prefer Permatex #2(?). It comes in a small (white)plastic bottle with a brush applicator top. It's a thickish dark brown liquid, that is alcohol soluble. It never hardens, and can be reusable in a pinch. I'm not 100% positive, but I think that is what MA Mopar used back in the day.
 
dano said:
Good to know. Hopefully that is not the case or my block is now scrap...

I do recall it tightening up the PS mount just fine and not feeling like I had to overcome some friction to get it tight. But it probably doesn't take much to puncture cast iron.
Click to expand...
It does not mean you used a too-long bolt; I just mentioned that to show that some bolts holes do indeed penetrate into the cooling jacket. It just means the thread in the front of the block are not sealed. Back that one out, and if it is free with only about 1/4" or so of backing out, then is ought to be the right length. It ought to be easy to tell if it is the right length.

And you can stick a thin rod into the hole to go all the way back to the cylinder wall and mark it to see how deep it is back to that part of the casting.
 
rustycowll69 said:
For sealing those bolt threads into coolant passages, I prefer Permatex #2(?). It comes in a small (white)plastic bottle with a brush applicator top. It's a thickish dark brown liquid, that is alcohol soluble. It never hardens, and can be reusable in a pinch. I'm not 100% positive, but I think that is what MA Mopar used back in the day.
Click to expand...

That's what I used on the upper bolts, and all the gaskets. We use it on all the engines we've built. Good stuff.
 
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