I'm wondering if anyone else has had this happen to them. This is the second Mitsubishi Evo Mivec Banjo bolt that has cracked on me. They go on fine and when I remove them they are cracked. I can see the wall is super thin and I only tq them to 20 ft-in per. The manual says 22.

I don't think it will fail, but it's concerning.

 

Never had that happen to me but that may be due to my car not having MIVEC

I once did snap the banjo for my turbo oil feed but that was my fault as I cross threaded it and it didnt seal so I tightened it some more, duh, before realizing what I had done.

Anyway, the design of banjo's are inherently weak since they are hollow by nature. Im not sure if this is "sound" advice but Im not a fan of using a torque wrench for things like that. Internal engine parts sure, lug nuts sure, but something like that with crush washers I just snug them until I feel the washer compress. 20 in/lb is nothing so I hope you've been using a 1/4" in/lb unit and even then I forget the rule but torque wrenches arent very accurate on the bottom 30% or something like that. And of course if you have a crappy wrench or it hasnt been calibrated recently then all bets are off.

 

I would use a tap on the threads you are trying to thread in to. It looks as if the female thread is a bit "aggressive." There may be 1 thread in there causing the damage. Especially if you have done this to more then one bolt. Just my 2 cents.

PS. If you do use a tap, make sure to go slow and take your time. You dont want any chips making its way into the line.

 

What are you seeing on those threads that I am missing? I see the crack but other than that nothing is really jumping out at me...its not a bad idea regardless to clean up threads but a tap is not the right tool for the job. Taps are for cutting new threads so if you are looking to "clean" them up a thread chaser aka a thread restorer is where it's at.

 

do not tap it. use a thread chaser. thread chasers are used to accurately clean up threads. keep using the torque wrench also.

 

Never had an issue using taps to clean up threaded holes. Been doing it for a long time. You just have to make sure you get the tap in straight, go slow, and use a lubricant. Use the method of going in two turns, then back off one turn, then going in two turns, back off one turn, and so on...


Bolts can usually be cleaned up with a triangle file.

 

Agree. Lubrication is key to ensure the rethread/clean up is as good as brand new. I've never had a clean up go bad. Following the method above.

 

Generally speaking I almost always agree with your feedback but not this time bucko!

I think this applies into the category of just because you can do something doesn't mean you should do it. Will it work? Of course it will. If you work slowly and keep it straight and are very careful it'll probably be fine. However taps cut new threads that is what they are designed to do whereas thread chasers sole purpose is to clean up threads that are a lil damaged or there is dirt corrosion etc.

Its all about using the right tool for the job. Even if the tap goes in straight and smoothly it's still going to take some material with it as its designed to cut vs a chaser which isnt aggressive at all and will straighten and clean.

I have both and am glad I do especially when Im cleaning up al threads