Thought I would cc a port in the cast iron heads I've been working on. Very first intake port I try has a leak. As seen in the picture, there is a very small pin hole in the casting. Metal thickness at the hole appears to be at least 0.140" according to my import ultrasonic gage. What are the options for leak repair? Braze? Drill/tap/plug? Or punt?
Pin hole in cast iron head
- Thread starter Earlie A
- Start date
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i fixed that same problem with splash zone epoxy 25 years ago and its still going .
that stuff is amazing . @pittsburghracer is the guy to ask maybe there is a better way to fix this now days .
Splashzone is some amazing stuff but I’m not sure it’s up to the task of holding up to water pressure over time. Is it possible it’s just a “void” or did you pressure test it??? Some of this nickel rod is amazing if the surrounding area is beefy and you can reach in and put a little “goonie” on it. But like a dear departed friend of mine told me. Don’t try to pretty it up to much after.
silver braze might be an option also .
No I’m talking welding. I’m not capable of doing anything in a port two handed like brazing or Tig welding. I just can’t devote enough time and practice to get good at it. Luckily I haven’t found the need. But like I said you have to have good surrounding metal and again like I said it’s a goonie weld to fill a void. If this was an aluminum head you could grind it out some, weld it with a spool gun, grind it again, weld it again, then pretty it up
Thanks. I have little welding skills so I'll have to look at braze/solder or tap and plug.
74 360 dart sport
Well-Known Member
Back in the day. I worked for a diesel head rebuilding company. I was the pressure tester on the assembly line. If I had a leak I took a round chisel and tap, tap, tap, retest and 99% of the time it sealed it up. Put my stamp on it and down the assembly line it went.
Now there's an interesting idea. Think I'll try that on a scrap head. Maybe a little splash zone forced into the hole before the peening?
i was just looking in my scribbler and where i fixed my head with SZ and it was further out in the port not the bowl like yours . That was 97 on a set of ported 308's lol .
30 minutes or 30 feet guarantee. Lol
jos51700
Green Bearing thread connoisseur
16psi times a hole .020" in diameter is like .005 pounds of force, if my math is right. There's not much force on that, at least from the coolant pressure with a 16psi cap. I would think most epoxies/bottle welds/brazes would seal that up.
Someone should check my math. I don't feel well today. Disclaimer, I'm just spitballing the hole diameter because OP doesn't say it.
Pour coolant on it and see if it drains out.
Someone should check my math. I don't feel well today. Disclaimer, I'm just spitballing the hole diameter because OP doesn't say it.
Pour coolant on it and see if it drains out.
Your math is spot on. I also think you are correct in the hole size guess. My concern with the epoxy is the long term. The force pushing on the epoxy would be 0.005 lbf if the epoxy stayed 100% adhered to the cast iron. If the epoxy lost contact with the cast iron, the 16 psi would be acting on a larger area. It is then a snowball until failure.
I like the thought of brazing/soldering but brazing especially would require high localized heat on a thin metal area. I have a buddy that's a great mechanic and fabricator, but even he is not that comfortable with cast iron.
I'm thinking of drilling a small diameter exploratory hole (in the existing hole) to try to decide if there is enough metal to tap/plug or braze. Seems like even brazing would want fresh metal.
Other thoughts - how big of a hole would radiator leak stop fix?
And it is a leak because my colored alcohol (that I use for cc'ing) slowly trickled from the port side into the water jacket.
I like the thought of brazing/soldering but brazing especially would require high localized heat on a thin metal area. I have a buddy that's a great mechanic and fabricator, but even he is not that comfortable with cast iron.
I'm thinking of drilling a small diameter exploratory hole (in the existing hole) to try to decide if there is enough metal to tap/plug or braze. Seems like even brazing would want fresh metal.
Other thoughts - how big of a hole would radiator leak stop fix?
And it is a leak because my colored alcohol (that I use for cc'ing) slowly trickled from the port side into the water jacket.
Newbomb Turk
Well-Known Member
There are several issues you will deal with.
One is cast iron. It’s problematic in its own right.
And then to that add all the scale and **** that is on that old cast iron. Even if you shot blast the head you will still deal with the remnants of that crap. Cast iron is dirty on its own. Used cast iron is nasty.
If that head was aluminum I would go in there with a grinder and clean out the area so I could get to the other side of the casting.
Then I’d weld it around, in and then out.
The biggest issue you’ll find is how thin the entire area is. You have to control the heat while still getting a clean weld.
You might get lucky if you can screw a pin into the hole and then weld the pin in place but that still takes heat.
You are between a rock and a hard place.
IMO I wouldn’t spend a second messing with it. You lose all your work BUT if you try and repair it and it fails you are out all that work too.
PRH
Well-Known Member
Belzona Super Metal will fix that right up.
Expensive, but it works, and holds up against ethanol blended fuels.
Expensive, but it works, and holds up against ethanol blended fuels.
Found it , this stuff will for sure do the job just pick the right kind for the job .
Belzona products - 1000 series
Belzona products - 1000 series
PRH
Well-Known Member
Two members on this board(that I know of) have ported factory heads that developed holes after they were put in service.
Both used Belzona to plug the hole.
One has been in service several years, the other only a couple seasons so far.
gzig5
Well-Known Member
Is there any access to the back side of the pinhole through the water passage? If there was, I'd try flooding the area with a thinned epoxy. You wouldn't need much to cover the hole and the material would be pushed against the wall by the water pressure. Should never leak. If I had to weld/braze it, I'd try blobbing some silicon bronze rod over that area with either oxy/acetylene or TIG. I recently repaired a broken cast iron part with a steel weldment to replace the missing parts. I used silicon bronze rod and TIG to join the steel parts to the original cast iron and with a bit of preheat and slow cooling, I was able to keep it from fracturing. The rod flowed well and doesn't require flux.
jos51700
Green Bearing thread connoisseur
That Belzona stuff is probably just as valid as JB Weld (I'd like to know what the differences are). I'm not sure how epoxy would hold up against fuel over time.
Maybe plain old plumbing solder? Water pressure in pipes is typically 55+psi, over a hundred if you don't have an expansion tank. Temp in the head should be less than 300 degrees unless you have other far more serious issues. Plumbing solder melts at 450+
Maybe plain old plumbing solder? Water pressure in pipes is typically 55+psi, over a hundred if you don't have an expansion tank. Temp in the head should be less than 300 degrees unless you have other far more serious issues. Plumbing solder melts at 450+
Drill it out to 1/16", then dress the area well to get fresh metal and all contaminants off then hit it with flux core wire in a mig welder and grind it back smooth.
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