Broken exhaust pipe/manifold bolts on 1994 GTX

[ueww40]

Recently my 1994 GTX took on cooling water and it seemed to be coming from under the exhaust manifold. Then I saw a broken allan bolt in the bilge and noticed that 2 bolts on the exhaust pipe/manifold were broken. Actually it was one broken allan bolt and one stud. The remaining 2 allan bolts I removed without a problem, but the one hex bolt that holds the exhaust pipe firmly to the engine (I think it is a M8x35 or 40) broke off as well while trying to undo it. The 2 broken bolts on the manifold I might be able to drill out and extract as is, but that other bolt is in such an awkward position that I either have to remove the 8 bolts from the manifold and remove the manifold or remove the whole engine. What is the best way to go? I don't want to remove the engine if I don't need to, but I am afraid that a few more of the 8 bolts will break when I try to undo them. Drilling out and extracting broken bolts is such a pain. All you guys out there with your bags full of tricks I would love to hear from you. Thanks Rick.

 

[ace422]

Post some pictures if you can.

 

[wabash]

Have you tried getting a hold of the bolt and removing it? Or is there not enough left to grab on to with Vice grips? If you can't get on the remainder of the bolt with vice grips and turn it out ,I would give those allen bolts a try and take the manifold off. The engine does not need to come out for this. If they've never been out they will still have Loctite on them from the factory and should come out. They'll be tight but they'll come out clean. If they're really tight coming out and it feels like you're going to break it off, stop and turn it back in a little then come back out. If that doesn't work then maybe you will need to pull the motor. But I'm betting the manifold bolts will come out just fine. What's probably happened is someone had the pipe off at some point and when they put it back on didn't put blue Loctite back on the bolts which did one of two things 1.) let the one bolt on the manifold come loose and break off which in turn breaks the stud, this is very common and 2.) If it doesn't come loose the stainless steel bolt will gall in the aluminum or the aluminum will corrode around it (because of the lack of Loctite sealing the threads) and it will break when you try too hard to remove it. SS bolts will break fairly easily. Give those manifold bolts a try.

 

[Strizzo]

Ideally you'd pull the manifold and there would be enough meat left to either cut a groove for a screwdriver, grab it with vice grips, or last resort, drill the bolt out.

Like wan ash said, someone before probably pulled the manifold, and likely didn't torque the bolts to spec (probably used the German spec) and they broke off. Those are particularly sensitive to being torqued correctly because the cast manifold expands quite a bit when it gets hot.

 

[ueww40]

Thanks for all your advise. You guys were right. I gave it a try hoping for the best and pulled the 8 bolts that hold the manifold. They came out easy and clean, almost like they were put in there yesterday. Now the manifold is on my bench and I can deal with the broken bolts. 2 have no meat left and need to be drilled. The 3rd is sticking out about 3 mm and I will try to mount it on my vice and carefully undo it. I am soaking everything right now in PB Blaster for a couple of days and then will go to it.

 

[Coastiejoe]

Left hand dill bits are your friends. They will often grab the remaining stud in the manifold and spin it out...


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[ueww40]

Left hand dill bits are your friends. They will often grab the remaining stud in the manifold and spin it out...

I didn't know there was such a thing as a left handed drill bit. Sounds good and I will go the the home depot tomorrow and see if I can get one.

 

[Coastiejoe]

I love them. Get a nice center punch and dent the bolt. Use a drill SMALL than the threads but as big as you can. Get the drill going and get some depth. This will heat things up a bit and get enough but into the stud to add nor stability. Then slow the drill down to the slowest constant speed you can at the same time pressing hard into the stud. This slowness will often grab and unthread the stud.


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[Luv2Camp]

Download a service manual. There is a torque pattern for tightening down those 8 bolts. One thing I learned the hard way with Rotax engines is to torque the bolts properly!