mcratchet1 Posted February 22, 2023 Share Posted February 22, 2023 Hey guys just was wanted a professional opinion I have 2007 Mack mr688s mp7 400hp the #6 exhaust mainifold broke bolt the top one, is this the cause of another issue or just old rusted bolt? Should I try to get the one bolt replaced or wait to see if another one breaks? Thanks in advance! Quote Link to comment Share on other sites More sharing options...
mowerman Posted February 22, 2023 Share Posted February 22, 2023 It’s just going to have possibly a small exhaust leak. I don’t think it’s anything to worry about. Removing Head is the best solution which is a lot of work… Bob Quote Link to comment Share on other sites More sharing options...
mowerman Posted February 22, 2023 Share Posted February 22, 2023 Oh, by the way, that’s not exactly a professional opinion that’s coming from a do it yourself er … Bob Quote Link to comment Share on other sites More sharing options...
Solution Popular Post mechohaulic Posted February 22, 2023 Solution Popular Post Share Posted February 22, 2023 a good set of left=hand drill bits many times make the job easier. have seen people use right hand drill bit on broken stud which wasn't that tight. drilling to use easy-out will tighten broken stud. left-hand on occasion helps loosen. your situation, i'd let it go unless exhaust leak starts. extended exhaust leaking will act like plasma cutter and will channel a grove in manifold. drill center of broken stud / spray penetrating oil and run it engine heat with penetrating oil might help the cause. 3 Quote Link to comment Share on other sites More sharing options...
Freightrain Posted February 22, 2023 Share Posted February 22, 2023 Start with penetrating oil over a few days, then left hand drill bit. May find it comes right out. Studs are typically installed hand tight, so unless it's rusty, it should come out. 2 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment Share on other sites More sharing options...
Popular Post fjh Posted February 22, 2023 Popular Post Share Posted February 22, 2023 Last resort is taking the head off! Manifold off and welding a washer and nut on often works that said wait till it starts leaking! highly recommending Try the drill bit option first! 3 Quote Link to comment Share on other sites More sharing options...
Vmac3 Posted February 22, 2023 Share Posted February 22, 2023 Common issue with these ASET engines. Left hand drill bit, penetrating fluid and welding a nut on the broken stud all work. try the easiest method first. You may want to double check the other studs and see if they are coming loose. V 2 Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted February 22, 2023 Share Posted February 22, 2023 Penetrating oil, left hand drill bit.. that looks like a trash truck engine. 1 Quote Link to comment Share on other sites More sharing options...
mowerman Posted February 22, 2023 Share Posted February 22, 2023 MR im sure it is..bob Quote Link to comment Share on other sites More sharing options...
mcratchet1 Posted February 22, 2023 Author Share Posted February 22, 2023 Ok thanks guys I’ll try the oil and left hand bit and keep an eye on them! It’s a concrete boom pump on its back lol Quote Link to comment Share on other sites More sharing options...
Mark T Posted February 22, 2023 Share Posted February 22, 2023 I'd look and see where it's broke. If there's a little stub sticking out of the head, let it go until it leaks or more break. Sometimes (if you get lucky) there's enough to get a small pipe wrench on. Most likely, you'll be drilling. It pays to put some effort into centering where you start to drill. Start with a smaller bit and drill slow. As everyone mentioned good left hand bits are a big plus.....along with a lot of patience. If you break a bit off in there ???? well..... you're screwed . I've had some success with a pilot hole then hog'n it out with a die grinder with a pointy bur in it. Patience ..... many have been removed on the truck. 1 Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted February 22, 2023 Share Posted February 22, 2023 you can put a inch long peice of fuel line in the manifold bolt hole to center the prick punch. Quote Link to comment Share on other sites More sharing options...
70mackMB Posted February 22, 2023 Share Posted February 22, 2023 How is it a "prick punch" when you start the job/repair. But if and when things go wrong it's not what it's call any longer. Asking for a friend. .....Hippy 1 Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted February 22, 2023 Share Posted February 22, 2023 Uhhhh,,,, A pointed small punch.. Quote Link to comment Share on other sites More sharing options...
mrsmackpaul Posted February 23, 2023 Share Posted February 23, 2023 Fill it up with the MIG until you have enough sticking out the manifold to weld a nut Then just unwind the stud and replace It is easier than you might think to do this I was dubious to say the least when I heard about this way but it really does work quite well If it keeps on breaking off, get a set of jumper leads and a couple of batteries series, maybe go three batteries Clamp one end to the head and the other to the nut you have welded on and put some decent currnt thru it This also helps to loosen things I think been a cast iron that this last step wont be needed Even if the stud is broken off a fare way down, just slowly build it up with the MIG Paul 2 Quote Link to comment Share on other sites More sharing options...
mechohaulic Posted February 23, 2023 Share Posted February 23, 2023 with the manifold (has tooo big a hole ) still in place , use a slack adjuster bushing or bushing similar to fit in manifold hole . using a drill which fits snug in the bushing you install. this gives you a better chance of close center on broken stud. a good drill will center "mark " stud. then with a left-hand drill, drill through the stud. i have gotten away from using smaller pilot drills simply due to fact have had toooo many pilot drills break;; now you have to get broken drill out. have NOT found a drill bit that will drill out a broken drill bit. that includes the carbide tip drills used for drilling the many 5th wheels installed. also using the step-down drilling process a drill bit is using the outer edge of the drill not the entire cutting edge . each project is different. in terms of your project with manifold still installed can't see if any of the stud is sticking out beyond the head. if can't be drilled out then manifold removal and welder to rescue . 1 1 Quote Link to comment Share on other sites More sharing options...
Popular Post Big R Posted February 24, 2023 Popular Post Share Posted February 24, 2023 (edited) I have seen but never tried using a piece of copper tubing to protect the hole when extracting a broken bolt. Find one that just fits in the hole then fill to the top with a mig welder. Easy then to weld a nut on Edited February 24, 2023 by Big R Miss spelled 2 1 Quote Link to comment Share on other sites More sharing options...
Popular Post mackaholic Posted February 28, 2023 Popular Post Share Posted February 28, 2023 On 2/22/2023 at 5:21 PM, mrsmackpaul said: Fill it up with the MIG until you have enough sticking out the manifold to weld a nut Then just unwind the stud and replace It is easier than you might think to do this I was dubious to say the least when I heard about this way but it really does work quite well If it keeps on breaking off, get a set of jumper leads and a couple of batteries series, maybe go three batteries Clamp one end to the head and the other to the nut you have welded on and put some decent currnt thru it This also helps to loosen things I think been a cast iron that this last step wont be needed Even if the stud is broken off a fare way down, just slowly build it up with the MIG Paul I've used the mig welder technique many times on Ford FE engines. Had very good luck getting the stud out without drilling. Takes 5-6 tries sometimes. Keep building it up until you can get a pair of vice grips on it then start gently putting pressure back and forth. 5 Quote Link to comment Share on other sites More sharing options...
Mean Green Posted March 4, 2023 Share Posted March 4, 2023 I like the copper bushing idea never tried that I sometimes use carbide drill bits they will drill through anything but you have to be careful as if they grab they can break the carbide out the end of the drill 1 Quote If your going to be a bear be a grizzly Link to comment Share on other sites More sharing options...
Freightrain Posted March 4, 2023 Share Posted March 4, 2023 On 2/28/2023 at 3:33 PM, mackaholic said: I've used the mig welder technique many times on Ford FE engines. Had very good luck getting the stud out without drilling. Takes 5-6 tries sometimes. Keep building it up until you can get a pair of vice grips on it then start gently putting pressure back and forth. Lol.....Ya FE's and those darn upper manifold bolts and the open hole. What a PITA. Been there, cussed a lot. 1 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment Share on other sites More sharing options...
tjc transport Posted March 4, 2023 Share Posted March 4, 2023 i remove manifold if there is still some of the stud sticking out, and weld a larger nut to what is left of the stud. fill the whole center of the nut to get a good bond with the stud. while it is still hot start turning it back and forth with a wrench. once loose run it out. much easier than drilling and using easy outs. 2 Quote when you are up to your armpits in alligators, it is hard to remember you only came in to drain the swamp.. Link to comment Share on other sites More sharing options...
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