My 1990 12 valve non IC head that i was originally told is good has a crack from the valve seat to the valve guide. Do any of you have any ideas what it would cost to get it fixed, or would it be cheaper to buy a new head and from where can i get a new head? I would appreciate any help on this.

 

Here's the scoop...

Assume that every Cummins head has cracks after 100,000 miles. Few Cummins heads have problems with those cracks before 1,000,000 miles. The majority of people who say that their head doesn't have cracks are people who aren't basing their statement on magnaflux results.

Cummins policy is that heads aren't reuseable during a rebuild. They don't even bother checking them anymore, they just spec a new one.

You will probably never notice a problem re-using the old head, even in a performance application. And if it does loose compression one day, all you're out is a head, gasket and the few hours it takes to change one.

Deck warpage is much more likely to cause problems than cracking between injector bores and valve bores.

 

My dads and I's company are one of 8 people in the world you can go threw and structurely weld cast iron and replease the guides with bronze guides

 

Exactly... Alot of people running around making good HP on "cracked" heads... They are surface cracks, they dont leak compression. Dont worry about it.

 

A new loaded 12v head is about $440 plus shipping.

 

Where from? i found one cast by cummins, loaded for $640. But its cast a little thicker in places where factory ones crack.

 

Again its most likly not an issue. If your worried do a compresion and leak down test.

 

www.rj-performance.

 

if you are infact getting a new one contact cummins_guy hes one of sponsors here he sells them for 398 loaded

 

umm, yes your head is ok, but some cracks are not acceptible, weather they leak compression or not, if the head is cracked around the seats ( if the head has replaceablr seats) it could cause the seats to loose the press fit, your 90 doesn't so your good there, and i have seen cracks on the top side of the head leak coolant, magnafluxing is a great tool, it can save you valuable time and money, however it will not tell you how deep the crack goes, just that there is one there. i would personnally get a new head or a good used one, i picked up a head for $50, had to bore and install exhaust seats cause they had cracks..... by doing that i removedd the cracks, and was vastly cheaper then a new head...... just my two cents