Single use cylinder head

[Rawze]

4 of 5 will fail a magna-flux, ex-ray, stress, and proper pressure tests by the time they get 450k miles on them. At even higher mileage, there is no sense in putting a single dime into all those proper tests and checks alone, nonetheless doing any machining work on it, I don't care what the quality of work they do it is.

More likely to fail than not, at high mileage, it IS going to fail one of these tests. Most shops cannot even perform these tests properly, do not have full methods meant for testing commercial heads, etc. nonetheless, could correct these types of problems successfully for long term use. it is a commercial engine,. not your grandmothers 454-chevy. The standards for commercial engines are nowhere near the same a they are for cars... Hence why they are expected to last a million miles instead of a hundred thousand miles.


-- Because BOTH OPTIONS are still in the several thousands of dollars range (if you did get it done actually right by some damn lottery-winning miracle),,.. There IS STILL the consideration of that fact that it costs the typical truck owner upwards of $10,000+ or MORE to replace the head if were not to last as long as a new one. -- It is a far cheaper, and wiser investment to just buy a certified OE reman or get a new one, considering there is not that much difference in price byt the time you get one in your hands again.


Lastly,.. I have yet to meet anyone who said their re-machined head lasted more than a couple hundred thousand miles before it had rto come off for injector cups, or excess valve seat wear, or some other thing that made an engine problem of some sort.

If you want a definitive, short answer then -- It is simply... the "before-1-million-mile failure" rate is consistently too high, even by top quality high-end machine/head shops vs new OEM and the cost/savings difference cannot justify the risk of a $10,000 repair, consiodering a machine head will typically only last about 25% - 30% of the time/miles of a brand new OE head would last.