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Dripping water behind header plate

Jay Williamson

Jay Williamson

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i recently purchased a 67 RT with a freshly rebuilt 440. When I first received the car, I pulled it in the garage and shut it off. I immediately heard liquid hitting the exhaust but didn’t think anything of it because it was raining like crazy out. The next day, I took it down the road and back and again pulled it in the garage, shut it off and heard the liquid dripping on the exhaust. Upon further inspection, I saw what looks like clear water dripping from between the third and fourth bolt and behind the header plate. I unbolted the header and saw there was a freeze plug in that area behind the plate. Just to be sure, I started the motor and let it warm up. I fully expected water to leak from the freeze plug or from around the manifold bolts, but it stayed perfectly dry. No dripping. I put the header back on and the next time I started the car, it dripped again. Could this just be condensation?
 
All of the header bolt holes are tapped into the water jacket. Threads are leaking. ( I Hope)!
 
zyzzyx said:
All of the header bolt holes are tapped into the water jacket. Threads are leaking. ( I Hope)!
Click to expand...
So they are tapped all the way into the water jacket and that’s normal? If that’s the case, can I isolate the leaking bolt, try to back it out and put sealer on it?
 
Jay Williamson said:
So they are tapped all the way into the water jacket and that’s normal? If that’s the case, can I isolate the leaking bolt, try to back it out and put sealer on it?
Click to expand...
In my opinion, to really have a good chance of getting a leaking factory exhaust manifold stud out without removing the heads would be to take off the exhaust manifold and heat up the head around the leaking stud with a torch & back the stud out. I've had bad luck with those studs & have broken several of them and had to pull the heads off.
 
yes, but don't use Silicone sealer. It'll only cause more problems. The factory uses studs
because the body of the stud is larger than the threaded portion. so it seals pretty good.
when using bolts, you have to use a good sealer like a Permatex product. I'm not sure
exactly which one. There's another thread just recently about this problem.
 
PurpleBeeper said:
In my opinion, to really have a good chance of getting a leaking factory exhaust manifold stud out without removing the heads would be to take off the exhaust manifold and heat up the head around the leaking stud with a torch & back the stud out. I've had bad luck with those studs & have broken several of them and had to pull the heads off.
Click to expand...
Hopefully it will come out easy since the motor is fresh
 
Here is a video of what I’m dealing with. Keep in mind that you are looking in a mirror facing up. There is a freeze plug behind the header plate right where the water seems to be dripping from, but when I removed the header, I could not see it leaking anywhere
 
I think I found the culprit. It took some work getting to it. First I had to remove the header. To do this, I needed to remove the spark plugs, unbolt the left motor mount and jack up the engine on the drivers side so the header plate would clear both the steering gear and header bolts. Once I got the header off, I found this. A freeze plug that has been leaking. The logical place for the leak would be around the outside rim, but it looks like it actually has a pin size hole in the center. I hope it comes out easy. My question is...should I put sealant around the outside rim before installing the new freeze plug? And if so, what kind of sealant would irk best?
Thanks!

9CFDC62E-F656-49B5-9239-EBB991FE88F1.jpeg
 
They NEVER leak around the rim.. other than initial install weep. They rot/rust through from too much water and not enough antifreeze. Permatex non hardening around the outside flange and knock the new one in with a socket the correct diameter. Do ALL of them on that head while you're in there.. worth checking the block with the headers already out as well.
 
WoW! You said it was a fresh 440? I don't know about that! Now you have me worried!
 
A habit I got into, on my engine builds, was to use Indianhead Shellac on the freeze plugs. I 'paint' a coat of it, on the sealing edge, but also on the inner surface. That seals, and protects the freeze plugs, from water corrosion. These days, I always use brass freeze plugs, but still do the same thing.
I suppose Permatex could work, too.
 
Problem solved. Freeze plugs replaced and leaks stopped. Now onto the brakes and parking brake
 
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