Magnum cylinder head crack
- Thread starter R72Demon
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Looks more like casting flash. Can you get a better picture?
I agree.
If it were a crack, there should be coolant leaking into it because the other side of the port is the water jacket... If it were cracked all the way through, there would be an antifreeze leaking into the port because it has more pressure than the exhaust port... The higher pressure would win...
Scody21
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Take some better photos. It could have had a chunk brake off from using the wrong grip length bolts and when tightened/torqued, it broke off the chunk. But it’s hard to see with this photo
And of course you felt it necessary to not include this information in your original question. Ok.
Yeah, I'd say it's a crack from someone putting a bolt in that hole and tightening the hell out of it or maybe over tightening the stud. If that hole is open to coolant, time for another head.
I didn't know that information yet when I originally posted the first post, I just started to investigate. I was just inquiring if this is common with Magnum heads.
This engine is new to me in a truck that I just purchased and drove home over 200 miles. No signs of smoking or coolant in oil. I started pulling it apart because the RH side manifold had a exhaust leak. Someone has been there before, the manifold is a Dorman replacement and the bolts were not OEM.
The bolts were likely too long, resulting in the crack. That appears to be one of the bolts for the two middle ports. If that's the case, I don't believe those go into coolant, but only the outside two on each head. So I would probably take a die grinder and clean the crack up a little and let it ride.
It is for the middle and actually none of the bolts go into coolant on the Magnum heads, they are blind holes.
Well that's good news.
TrailBeast
AKA Mopars4us on Youtube
Scody21
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Could use some high temp epoxy over the crack…. Or buy a head or 2 from the junkyard and have them crack checked…
Ok, so it's not into the water jacket, it's a blind hole for the exhaust manifold that is cracked through to the exhaust port...
Threads are not perfectly sealed and some air/water can pass between the threads and leak... That may have also been making an exhaust leak noise...
Since exhaust gasses are not good to breathe and long exposure can kill you, I would recommend using high temp thread sealant to keep any exhaust gasses from passing through the threads into the engine compartment and possibly into the cowl and get sucked into the HVAC and circulated into the interior... Especially when it is cold and you are using the heat, the HVAC gets it's air supply from the cowl... Any exhaust that leaks from the engine compartment can enter the HVAC through the cowl...
I would recommend using a high temp thread sealant to keep exhaust gasses from leaking into the engine compartment and possibly into the interior and causing carbon monoxide poisoning... We're talking life and death, don't take any chances...
You need something that can handle high temp from the exhaust... I did do a google search and found a couple of sealers that are rated up to 1800°F, this first one is 2000°F and affordable...
Here's a link and it's not too expensive:
https://www.amazon.com/Vibra-TITE-1...ocker-Translucent/dp/B07XW2ZTZL?tag=fabo03-20
Then there is this Deacon 8875-Thin thread sealer... It doesn't list a price but is rated to 1800°F... You need a thread sealer, not a thread lubricant like some of the other products they offer... This is the one I would use if I chose this one...
Here's the link for that one:
https://www.jetlube.com/product/deacon-8875-thin-thermal-reactive-paste-sealing-compound
Permatex makes a hi-temp sealant, but it is only rated to 400° F... I included this to show you an example of what not to buy for this...
No good for exhaust temps...
Spend the money to seal it correctly, it's not worth the risk to you and your family...
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