Engine/Transmission (1994 - 1998) Cracked Head.

[JTroiano]

Has any one seen a 12 valve head crack on the outside between the exhaust port and the injector? It is about 1/2" long and only seems to leak a little when cold. There is no water in the oil and its does not loose any water so it has to be loosing a very little. I just got this truck on the road and the head has quit a bit of money in it, so I would like to keep running it if its just a casting flaw. I inspected very closely between the intake and exhaust valves and did not see any cracks.



The other question is if I do need to change it. Can you put a 24 valve head on a 12 valve block? Do they flow better and crack less? I know I will have to get custom lines but what about the injectors?



Any input would be great.



Jon T

 

[Forrest Nearing]

stick with the 12v head. I say run it till it becomes a problem.



I've seen them crack at the exhaust ears from the manifold pulling on them. is it on the #1 or #6cyl?

 

[Bandit1]

mine did it.

 

[JTroiano]

I going to keep running it for now. I had the head surfaced and "O" ringed, so I don't want to spend the cash again. I can get another head free and get it surfaced for free but the $400. 00 for the "O" rings I can't afford right now.



Thanks for the reply's



Jon T

 

[KDHannink]

cracked head fix

My brother's 97 12v head cracked at the ears on the #1 and #2 exhaust ports. One ear was completely off. The crack happened during some "fun" on a dry lakebed when trying to get a 4th gear donut going and killed the motor at full heat. The fix was to braze it with simple copper brazing rod after about 2 minutes of moderate heat under an oxy-acetelene torch, and it is holding so far. Permatex Cold Weld actually worked until the exhaust manifold bolts were retightened after it set for a week. I would try to braze it if possible. Make sure to grind out the crack as much as possible, as if you were going to weld it. If we could do it over again we would practice on an old cast iron head or something to get the feel of how the brazing rod will act under heat. The copper will actually flow uphill if it is hotter above where you apply the brazing rod to the heat. Also will have to get the fuel return lines out of the way. Good luck

 

[JTroiano]

I haven't brazed anything in 20 years. I remember people brazing cast iron. I think it helps to pre heat the cast iron and then try to cool it slowly.



If it get worse I will give that a try. What to I have to loose.



Thanks for the info.



Jon T

 

[Dieseldemon]

24V head will not work on the 12v block unless you change to the 24V pistons and injectors and Ex manifold and you would need the inj lines from Schied diesel for the P7100 to 24V engine conversion + misc parts in the fuel sys. Not worth it