i sent my head out to have it o ringed. scott at mass diesel called back and said it was cracked in 5 places. he had another head there off a running engine he would sell me but he called today and that one was cracked to. i was wondering if anyone else has had a 24v head crack on them.

 

Probably every head out there has cracks in the exhaust seat area. Have them pressure check it, if it doesn't leak there's no problem. My cylinder head has about 15 cracks in it, runs great. Did they say anything about the valve guides ?? They tend to wear out at very low miles. Thanks Steve B.

 

i guess my original head was cracked between the exhaust in 5 spots

 

Very true, this was the cause of alot of headaches for me with one I had bought that was rebuilt and o-rings. Couldn't get a good seat cut into it because the guides needed to be done first.

Mine at 87,000 miles had valve stems that were worn beyond reuse. And my original head as about 5 cracks in the exhaust seat area and it pressure tested out ok. Just needs to be rebuilt.

 

Well, not to complicate the matter, but it would be nice to know where the cracks are and what methods they use (magnaflux or pressure testing) to test the head. If there are cracks in the exhaust valve seats this is not good for performance as you risk losing compression not to menchon how critical that valve to valve seat seal is. With the heat of combustion you don't want to be leaking that combustion past exhaust valves or seats on the compression stroke. . Operating that way too long can gutter out the valve and then you have no compression on that cylinder. Then the head gets to come off again. Sounds like you may need to get more info from them. If the crack is in the combustion chamber or going into the water jacket then its a no brainer.

 

2 yrs ago w/ 300,000 miles I had my head off to replace leaking hg. Wanted to have the valves redone and had it magna fluxed. There was around 12 small cracks thru out the head around the valves near the seats. I just ended up buying a reman head form cummins.

 

I went through this when I had my head machined... The day I brought the head to Ray Macs he showed me 100s of heads from cummins that he would not even touch because of the cracks! From personal experience he told me that almost 75% of the time 3rd gen heads always came back cracked, 2nd gens were next and 1st gens were the best at coming in uncracked (marginally 2nd and 1st gen about the same).... These heads were checked by magnafluxing... Lucky (thank God!) my head came back uncracked... However a valve job couldn't be done until I replaced every single valve guide! The stock guides were wallered out in an oval shape! Was hideous to look at.. Could actually see where the valves would hit the side of the seat and then slide into it... Was painful to shell out the $$ formnew hardened steel seats, but it's done...

Head was decked, fluxed, new valve cut, new valve guides, new viton seals, .043 orings, modified marine gasket, F1 springs... Was an expensive couple of weeks!


SO ya these heads are BAD about cracking!

 

Most all heads have small hairline heat cracks, but if it passes the pressure check there should be no problem using it.

 

That why you get it pressure checked. Magna Flux shows the cracks. Pressure testing shows if the cracks LEAK. If it doesn't leak use it. Thanks

 

Lock-N-Stitch is supposed to be an effective repair for otherwise ruined cylinder heads.

 

You can reuse a cracked head if you want. I'll pass. Were talking about two slightly different things here. The micro cracks around the exhaust ports and seats vs. cracks due to jacket water loss and over temperature or jacket water overheating. If you have cracks due to overheating they're going to leak uder pressure. I understand the reason for magnafluxing and pressure testing. Thanks.

 

Yes you are, I'm talking about the cracks in the exhaust seat area. I don't think anyone would reuse a cylinder head that leaks combustion into a water passage. I'd pass on that also !! Thanks.

 

Old mechanics sales pitch that has been going on since Chrysler built the hemi in very early 50's. Think it out.
The valve(s) were or not burnt or damaged.
It did or didn't have a overheating problem.
It was or was not blowing coolant.
It was or was not hydraulic locking or losing coolant or blowing white smoke.
The combustion chamber is cleaner on suspect cly than others.
The head passes or fails a pressure leak test.
The cracks are superfical. Can you hang a fingernail in them? Are they open and you can see a crater.
The metal in the general area that cracks show is perhaps 1/2 inch thick.
A explination: As metal heats up it expands and creates extreme pressures since combustion area is hotter than rest of head. When it cools the metal tends to pull itself apart forming the crack. Do this a few thousand cycles and you get visible cracks.
Did you ever see a heat checked flywheel. Same thing. Not a real problem but can resurface and feel better with only few dollars spendt.
If you really had a crack, there are casting repair shops that heat the head to some very high temp and flow special welding material into crack. Then cool it very slowly to relieve pressures. Had a $6,000.00 JD head saved from junk by this procedure.
Just have to vent sometimes on good intentioned unknowing(?) shops for trying to make a living.