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MG MGB Technical - Exhaust: Studs or bolts?
I'm about to pull the engine again, to fix the rear main oil seal. I have a one piece exhaust (extractors and all welded together) and removing and more importantly replacing it with the studs is difficult at the best. Last time (about a 2 weeks ago) I simply cut the pipe and had it welded together again. Now I'm wondering if there would be any issues in removing the studs and when replacing using bolts to hold the manifolds in place?
|I use stainless steel bolts, at the front and rear of the exhaust manifold, to facilitate removal of the exhaust system. I don't see why you couldn't use bolts, as long as you have the clearance to get them started. RAY|
Be sure to use antiseize compound when you put the bolts in, or you'll have a devil of a time when you go to remove them sometime in the future.
|In principle no, that is how the V8 is. Not had a problem with steel bolts in an alloy head, at least.|
If a stud seizes in the head, the nut might still come off. If a bolt seizes in the head, it is going to break. I would use studs.
|C R Huff|
|I'm with studs too for Charley's reason plus it's easier to wiggle the relatively heavy manifold to get it on the studs whereas wiggling a 1/4" bolt to get it started on a thread while holding the heavy manifold could be tricky. You cannot have much clearance on the holes or the alignment will be out. And you can only use bolts for the two outer holes, if you want to get the manifold off without removing the carbs (there's precious little space to get the nuts off, so a bolt will not come out) - at least that the case for an SU manifold. Not sure about using stainless steel; more chance of getting steel bolts out I reckon.|
|Keep the studs,let the headers hang loose until you start to pull the engine/trans, the headers should slide off the studs. Ric|
Thanks for the responses.
As I said in my original post I have extractors, not the cast iron headers. These extractors and the whole exhaust system are one piece, welded together, therefore the exhaust cannot be removed from the car, without cutting. It can be removed from the head, but with great difficulty and with some damage to the threads on the studs. My concern is not so much in removing it, but in replacing it. I am concerned that when lowering the engine and gearbox into the body the studs may catch the exhaust and mangle it. Bolts would allow the exhaust to slip off the side of the head and when replacing minimal danger of damaging it, as there is nothing protruding.
I appreciate the comments about the bolts or studs seizing in the head and that removing the brass nuts would be much easier. As was mentioned, above, use anti seize gunk with bolts may be the way to go.
I guess I didn't really understand your problem before. So, sure the bolts could be used.
If it were mine, I would be more inclined to put a joint between the exhaust header and the pipe. That should also allow you to remove the engine with the carbs and header still in place. The band clamps are pretty nice for this purpose if you don't like the cheap looking u-bolt clamps.
|C R Huff|
What I have done is a mix of the bolt and stud solution. I've decided to stay with the studs, but to remove them like the bolts, before lifting the engine.
As an aside I've found a new place for oil leaks, through the stud holes, so I guess when it comes time to replace them I need to use some form of sealant.
Further to my last email, I removed the studs and proceeded to pull the engine. Major problems, the exhaust pipes fouled the engine so that I had to do a lot of pushing shoving and straining to get the d**m thing out. There is no way it will go back in, with the exhaust in position.
Well I have to bite the bullet and cut the pipe and provide some sort of openable joint.
Looks like studs, with sealer on the threads, are here to stay.
This thread was discussed between 04/08/2010 and 10/08/2010
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