The T I just sold has developed a small hairline crack on the top of the head running from the outlet water neck straight back to above # 2 plug. I told the new owner I would repair it
It is a small seeping crack.
I am considering grinding down 1/8" along the crack line and then
1. either filling it in with mighty putty or
2. have a welder weld (iron) crack shot then grind weld down smooth
3. finally replace the head if all else fails
any other ideas? Since this is not a pressurized head I am thinking trying number 1 first and see what happens also what in the heck could have caused a hairline crack in the top of the head????
I don't think you can have this head welded for less than the cost of a replacement head. I have several cleaned, magnafluxed to verify crack free and surfaced to verify flatness high heads on my shelf and cannot find a buyer for $35 each. The shipping cost from WA to Indiana would be prohibitive. Perhaps some of the plastic fillers like JB Weld is your best bet. I would guess some sort of thermal stress caused the crack. Perhaps the engine was run while low on coolant and over heated or perhaps the coolant temperature dropped below its' freezing point. These are just long distance guesses though. I suppose a spark plug could be tightened enough to cause the head to split, tapered pipe threads are used on the plugs, but this seems rather far fetched to me.
A mechanic once told me to "Press steel wool into the crack and drive the car until the steel wool rusts enough to plug the crack"
Not sure if that was good advice though
A hairline crack can develop for a couple of reasons, the most notable being run without water and that extra thermal expansion causes internal original stress in the back to try and move too quickly on cooling.
Actually, you are on the right track, it is a non-pressurized head, so...just stop the crack from spreading by drilling a hole at each end, not too big but do use a sharp drill. Some plug the ends buy press fitting a chunk of copper rod and filing smooth to contour.
The crack itself will eventually rust itself shut provided it is a real hairline and not an open crack...but you probably don't want a weeper on your rebuild until it seals. In that case dremel or die grind it out a bit, and you can try a filler....but...the best would be what is called a rust joint where you can make that rust seal in about 24 hours.
Get a sal amoniac block at a solder supply store...lifetime and then some supply for about 3 bucks.....buy some near pure sulphur tablets at a health food store for about 2 bucks...also a lifetime and then some supply.
The proper mix is 80 parts iron filing, 1 part Sal amoniac, 1 part Sulphur. That works out to be a nice pile of iron, a pinch of Sal Amoniac, and a pinch of Sulphur Mix it up, wet it enough to be a putty, and then pretend it is bondo! In about a day it will be as solid as a rock and water tight! Grind/Sand it out smooth to profile and good to go!
Sound crazy? You'll be amazed at how well it works!
David: first the material in the top of the head in not thick enough to grind it down 1/8 inch. You are lucky to find it 1/8 inch thick.
I suggest you widen the crack by grinding with a thin cut off blade or a mounted stone ground to a sharp edge. I have had good luck using 50/50 solder. The crack you describe is a hard water crack. (ice). No need to do any drilling. The stress that caused the crack is gone. Tin the ground crack well, using acetylene torch for heat and Ruby fluid for flux. Propane is not hot enough for cast iron. Fill the ground crack with solder, file smooth if you like and after painting the repair will not be noticed. As long as you keep coolant in the engine the solder will last forever. No coolant your engine will self distruct and you won't care about the soldered crack.
If its in the spark plug threads, replace the head. If not then v out the crack and fill with JB weld or similar quality epoxy. Do a little body work and paint the head.
If I sold the car and had assured the new owner there was no crack, I would replace the head.
If I had the option, I would give them an uncracked head. Then use the cracked one myself. Those cracks are usually nothing to worry about. FIRST, drill, tap (about #8 or #10-32), short screw, cut off and peen the surface at both ends of the crack to keep it from growing. George's suggestion may be the best. I know of it, but have never done it. OR Dremel tool a small "V" in the crack, and use the thinner "two-ton" epoxy, it is best for a water jacket cracks as it soaks into the crack better.
Welding the crack is an expensive proposition. Welding it there WILL warp the head requiring having the head resurfaced also. Been there, re-broke that.
Drive safe, W2
A friend of mine rapaired a small crack in his head (that didn't sound right) with JB Weld about a year ago. No stop drilling, just ground a small V and filled it up. So far, it is holding up well.
If you are coming out to The Denver Area soon I will give you a high head, I have about 25 of them. Cecil Paolietti is right not many sell. I use them for weights on my tubes when I irrigate in the summer.
Dave, if your going to be in Indianapolis area I have a head I'll give you.
A friend recently tried to repair a head by arc welding and the heat (although it was not a lot) just made the crack grow as he tried to weld the crack he could see.
I did sell a high head last year for $50, but that was after it was sand blasted and magna-fluxed, which cost me $35. I still have several too.
Thank you all for the superb advice
I did not know that welding would warp the head and did not know how thin the head was at that point
Thank you for all the offers
Superb advice from this forum
Get the crack absolutely clean. Under-cut the crack a little with a dremel tool and fill it in with regular JB-Weld (the stuff that takes 24 hours to cure). This is General Motors repair procedure for dealership technicians to fix Oldsmobile Aurora 4.0 Liter aluminum blocks with water jacket cracks under warranty in the 1990's. As far as I know, none ever failed. If it works on a modern aluminum engine with a pressurized cooling system that probably has at least two heating/cooling cycles every day for a decade, it should work fine on a Model T head (especially since a head is so easily replaceable even if it does fail).
I have no experience with this system.
James, they can be arc welded very easily, I've done it when I didn't have a good head handy. The trick is to preheat the head to where it is uncomfortable to hold your hand on it. I used gouging rod to chamfer the crack, this helps burn out rust and other foriegn material, where grinding tends to imbed it. I also had the head bolted down on a block. Now, the thing to do is, backstep weld it, start in the middle of the crack, weld about a half to three quarters of an inch, stop pien the weld. Then go back the other direction and weld TOWARDS the first weld using the same procedure. By welding towards the center, alternating from each side, as the weld cools it tends to pull the crack together instead of spreading it apart. Just go slowly making sure not to get the weld area too hot to quickly touch it after piening. That being said, finding another head would be my first choice, but this method also works well on many other things. Dave
You could always get one from ebay!
Nice little profit "old fart" is going for! Hmmm... could be a good retirement plan... ebay... Valuable old Ford parts...Heck this could be better'n Amway!
Wow, I'm rich! And to think, I was going to give one away. OK, I'll only take $150 for mine.
I've had good luck with JB Weld on heads and cracked water pump bodies. The key is to put it on plenty thick. Thin applications won't hold up. I speak from experience here.
V out the crack really good and big, clean it well with solvent and apply the slow drying type of J B Weld. I have used window screen mesh embedded in the J B Weld for added strength and to hold the J B Weld in place while drying.
If you can reach the area, place tape underneath the V to hold the J B Weld in place.
The repairs I've done this way have held.