I've been a Proto-type R&D and Commercial O&R precision machinist/fabricator in both Military and Commercial aerospace for well over 20 years now and can tell you the following...
1. That crack is more than likely the result of "thermal casting stress" and most likely occured during "cool down"...at the point of original oem casting process and has always been there but you just recently noticed it.
2. It was not the result of "Over-Torquing The Bolt"...as if it were?...the crack would eminate from the threaded I.D. (hole) outward...and not "from the external surface inward" as depicted in the photo's.
3. IMNSHO...weld repairing such a crack would only be a last resort as welding it will just induce more heat and more stress increasing the chances that another crack may appear elsewhere's...and if I did choose to weld it?...it would be done with that cast component removed from the engine and completely stripped down and properly weld preped.
4. My suggestion for concern/repair would be as follows....
If it's NOT a "Through Crack"?: Use some high heat RTV as a thread sealer, re-install the bolt and forget about it.
If it IS "Through Crack"?: Consider a small isolated area "Low Heat Braze Repair"...as low heat braze is far more suitable for castings and induces far less heat related stress....and for bonus points?...you don't hafta worry about frying any internals or electronics.
5. And I'd only attempt to braze it if it were leaking...otherwise?...just apply a liberal coating of high temp RTV to the bolt, replace it with light torque (so as not to make it any worse) and then just forget about the crack you just noticed that's probably always been there and...
L8R, Bill.
1. That crack is more than likely the result of "thermal casting stress" and most likely occured during "cool down"...at the point of original oem casting process and has always been there but you just recently noticed it.
2. It was not the result of "Over-Torquing The Bolt"...as if it were?...the crack would eminate from the threaded I.D. (hole) outward...and not "from the external surface inward" as depicted in the photo's.
3. IMNSHO...weld repairing such a crack would only be a last resort as welding it will just induce more heat and more stress increasing the chances that another crack may appear elsewhere's...and if I did choose to weld it?...it would be done with that cast component removed from the engine and completely stripped down and properly weld preped.
4. My suggestion for concern/repair would be as follows....
If it's NOT a "Through Crack"?: Use some high heat RTV as a thread sealer, re-install the bolt and forget about it.
If it IS "Through Crack"?: Consider a small isolated area "Low Heat Braze Repair"...as low heat braze is far more suitable for castings and induces far less heat related stress....and for bonus points?...you don't hafta worry about frying any internals or electronics.
5. And I'd only attempt to braze it if it were leaking...otherwise?...just apply a liberal coating of high temp RTV to the bolt, replace it with light torque (so as not to make it any worse) and then just forget about the crack you just noticed that's probably always been there and...
L8R, Bill.
