Technical question: options to test head with cracks

Hi, Neil.
I YAIN'T a mechanic or mechanical engineer or any of those expert-type people but it is my understanding that if a head is not leaking either water or compression into places where it oughtn't and will seal to the block, it ought to be serviceable - given that all else is still O.K. - like rocker mountings, etc..

Since your post on 'Highway Alert' yesterday, I have been racking my tiny brain trying to dredge up a 10-plus-year old memory. Back about then, I became aware of a welding company on your side of the puddle and, I think, close to your neck of the woods, that specialised in difficult and 'tecker-nickel' welding jobs. The bit that I found really interesting about them was that they would send the 'how-to's' out to people who could not get the job into their workshop. I am fairly sure that I posted the information on the old forum either just before or just after the 'melt-down' when South40 stopped running the forum, back in about 2000-2001. I have just submitted a 'HELP' request asking if it is still possible to access those old posts. I hope that it is still possible 'cos there was also a LONNNGGGGG list of service providers that I posted back then, many of who may well still be around.

Fingers crossed, both for the retrieval of the information and for your heads.

Just my 0.02.

[quote="Deas Plant."]Hi, Neil.
I YAIN'T a mechanic or mechanical engineer or any of those expert-type people but it is my understanding that if a head is not leaking either water or compression into places where it oughtn't and will seal to the block, it ought to be serviceable - given that all else is still O.K. - like rocker mountings, etc..

Since your post on 'Highway Alert' yesterday, I have been racking my tiny brain trying to dredge up a 10-plus-year old memory. Back about then, I became aware of a welding company on your side of the puddle and, I think, close to your neck of the woods, that specialised in difficult and 'tecker-nickel' welding jobs. The bit that I found really interesting about them was that they would send the 'how-to's' out to people who could not get the job into their workshop. I am fairly sure that I posted the information on the old forum either just before or just after the 'melt-down' when South40 stopped running the forum, back in about 2000-2001. I have just submitted a 'HELP' request asking if it is still possible to access those old posts. I hope that it is still possible 'cos there was also a LONNNGGGGG list of service providers that I posted back then, many of who may well still be around.

Fingers crossed, both for the retrieval of the information and for your heads.

Just my 0.02.[/quote]
Was it perhaps in Greenville, Mississippi?

Can't remember a name but shipped some heads there for repair 40 years ago and they did an excellent job. The heads looked like new and gave good service when I got them back.

Thanks guys, and I've been having conversations with the engine rebuilder about those shops that weld the heads up, and from my understanding, they can fix pretty severe issues (not just cracks but whole broken out pieces) with satisfactory (i.e. will last) results. As you'd expect though, the price is commensurate.
What I'm trying to figure out is, is there any way, other than reinstalling the head and running the engine, to find out whether it leaks? Reason I ask is because the heads are both off and if I could tell, then if one of them doesn't leak, I'll get the valve seats, guides, etc. done on it. My head has pretty bad valve seats so I don't know if it would run well enough on that cylinder to be able to check for leaks, and John's head has a couple of the seats out already.
Of course, if Ken's head tests ok on the magna flux, then I'll take that option. I suspect though, that the engine rebuilder will find cracks and assume that the head is no good. But I wonder if all D3400 heads that have seen some service have cracks, and it's just a matter of whether they leak or not.

Depends on where the cracks are.
Typical test methods are magna-flux, die penetrant, and pressure testing.

Welding is not always the best repair but the old art of stiching seems to be lost. Any significant cracks into the valve seat area need repair and inserts installed.

Fine cracks can be sealed with Sodium Silicate (water glass). Works best on super clean water jackets.

Obviously the final test is on the engine where you get the temperature/expansion influence.

Thanks OM, could you elaborate on dye penetrant and pressure-testing. For the latter, am I close that a jig would have to be set up to simulate combustion pressures on the combustion surface of the head? Not familiar with the dye penetrant method but would guess that we're looking for dye to show up places it shouldn't, under pressure?

Stitching is still popular East of the Mississippi.
A engine rebuilder in Olean, NY does it routinely, we here in WI get it done locally also.

Die/Penetrant would require the penetrant spray on one side, then the die on the opposite side.
Its a visual thing where the die changes color in contact with the penetrant.

As far as pressure testing, It works but I have always been of the opinion it works even better when Thermal Expansion is involved.
You figure that part out, then go for it!

If it was me, I had a running head, I would use it.
I don't believe you will ever find a head that won't have at least one crack in it.
(not saying "Won't)

The stiching I'm referring to is done with tapered threaded cast iron plugs done with tapered drill and tap, intersecting each other along the crack. "Irontight" is the product name if I remember correctly.

The die penetrant is a two spray can process. The die (usually red) is sprayed on a clean surface and allowed to soak, then wipe off the excess and spray with the light colored developer. The remaining red leaches through and indicates the crack. Commonly used on aluminum where magnetic particle testing doesn't work but works fine on other metals as well.


Pressure testing requires plating and sealing the head surface, usually with 1/2" to 3/4" thick polycarbonate plastic. Also various water connections need to be covered. Pressure is preferably done with normal operating temperature hot water. Air pressure can also be used and the whole head submerged for bubble check or a soap/water solution sprayed on accessible areas. Pressure for either test usually does not exceed 3 X normal cooling system pressure.

[quote="Old Magnet"]The stiching I'm referring to is done with tapered threaded cast iron plugs done with tapered drill and tap, intersecting each other along the crack. "Irontight" is the product name if I remember correctly.

The die penetrant is a two spray can process. The die (usually red) is sprayed on a clean surface and allowed to soak, then wipe off the excess and spray with the light colored developer. The remaining red leaches through and indicates the crack. Commonly used on aluminum where magnetic particle testing doesn't work but works fine on other metals as well.


Pressure testing requires plating and sealing the head surface, usually with 1/2" to 3/4" thick polycarbonate plastic. Also various water connections need to be covered. Pressure is preferably done with normal operating temperature hot water. Air pressure can also be used and the whole head submerged for bubble check or a soap/water solution sprayed on accessible areas. Pressure for either test usually does not exceed 3 X normal cooling system pressure.[/quote]

A fixture is made to hold the head, and has numerous discs covered with rubber, on adjustable swinging arms, and attached to screws to apply pressure, to seal all the water passages. Then the water passages are filled with solvent, and pressurized. I have seen one used, but don't remember the name of the manufacturer. Maybe some company like Lisle, Van Norman, or one of the other companies that specialize in the automotive machinery field.

I went through this on my D4400 went through a number of heads before we ended up taking the best one to a shop that does this work (Rettig Brothers, Modesto, CA) On the D4400 all of the cracks were on either the #2 or #3 exhaust port area.

The shop put in a series of pins that overlapped. Then they pressure tested and re pinned until there were no leaks. Last thing they did was ceramic coated the water jackets to prevent any small leaks.

I want to say fixing the cracks was in the $300 - $400 range. All told after guides, valves s and seats I am probably into it $1000.