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Discussion Starter · #1 ·
Well, I've got a cracked injector seat/orifice in the head on the #1 hole and maybe a tiny one on #4. I talked to a head guy and he said it was hard to tell. I can see the crack and felt it with a dental pick (barely).
I have the older 9mm orifices and just had my injectors redone so my questions are as follows? Are these heads usually repairable? What do repairs typically run? Should I just look for a new motor seeing as my injection pump needs a going through (reman is $795) and the turbo does to?
I have great compression and oil pressure. My thought at this point is to pull it and take it down and have it checked out. With many used motors I still might find some gremlins so I ought to see what needs to be done as I want to have a solid motor that won't need much tlc after a swap.. Your input is greatly appreciated and if you have a head in excellent shape for my cpl 593 motor with 9mm injectors let me know, thanks, kief.
 

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Your cylinder head is probably still usable and/or repairable. You need to review the guidelines in the service manual starting on page 7-56. If the crack extends into the valve seat you will need to install a replacement valve seat in the head.
 

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All early 9mm heads with any time on them will be cracked. I would just run it.
 

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Discussion Starter · #4 ·
Really?

All early 9mm heads with any time on them will be cracked. I would just run it.
I am getting some substantial leakage around the #1 injector, and a trace around #4, Won't it just get worse?
My thinking that after being swapped into a 5 to 6,000 lb. rig with a 5 speed this rig is going to have a much easier life, subjecting the head to a lot less overloading/lugging. ( the van had a sm420, 3 speed with a granny 1st and the spacing between 3rd and 4th is BAD. If I can get 100k out of it vs. 20 to 50k it seems worth fixing but it may just stay the same and not grow(?).
 

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I am getting some substantial leakage around the #1 injector, and a trace around #4, Won't it just get worse?
My thinking that after being swapped into a 5 to 6,000 lb. rig with a 5 speed this rig is going to have a much easier life, subjecting the head to a lot less overloading/lugging. ( the van had a sm420, 3 speed with a granny 1st and the spacing between 3rd and 4th is BAD. If I can get 100k out of it vs. 20 to 50k it seems worth fixing but it may just stay the same and not grow(?).
My 6BT had cracks, and as my machinist pointed out it can certainly only get worse with time. I just bit the bullet and replacedit while it was apart.
 

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If at all possible I'd at least try to pick up a spare head now if you're able.

There's a few fixes for cracked heads. Normally the method is to 'stop drill' it. This is to define the absolute extent or ends of crack, either sonic or magnaflux, and then drill down entirely through the very end of the crack at each end. These holes then relieve pressure/stress [stress riser] and stops the continuation of cracking.

Some will then fill the drilled holes with a soft steel dowel. It's best to heat the head very hot, as per standard cast iron welding, then either weld or braze the crack with it hot. After welding the head may then be thrown into a fire of coals and covered, and left to morning. This slow cooling prevents further stress risers from occurring and 'tempers' [not the right word] the iron.

After welding or brazing it is then resurfaced to level. There are a few types of high nickel content arc welding rods specifically for cast iron, or TIG may be used, but I prefer brazing. With so much mass in the head and the need for maintaining the surface true it's just as well to braze and heat treat as to attempt 'cold' cast iron arc welding.

With part of the crack extending into the injector bore it's still possible, as per above, to prevent any further cracking. In fact the injector hole may also be welded shut, redrilled and tapped. The cost of some cylinder heads is in the 10's of thousands of dollars, and you just don't throw them away when they crack! Yes, you can do this job at home, if you have the equipment.
 

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Discussion Starter · #7 ·
yup

Replacement seems like a viable option, especially if repairs run over $300+, not that they would, then I would think it would be wise to go to 7mm inj, buy new injectors and sell my recently rebuilt ones..
I don't think it want to attempt repairs myself. There is a machinist in town who has a good reputation for fixing heads.
 
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