All exhaust manifold bolt sheared off stud, best option?
Discussion
All 3 heads have sheared of the exhaust manifold studs that connects the middle exhaust section to lower manifold. It's also a manicat.
I have the manicat out of the car and so far I've drilled through one stud, I've tried bolt extractors in the hole but nothing, I assume I'll have to drill the bolt out and use a tap and die set and probably a heli coil to make it useable again?
What would you do taking into account that a new manifold will be quite expensive due to having the CAT attached to it.
Would a machine shop likely be expensive?
Could you get away with no thread in the hole and just put a bolt through it with nut on other end. The thread is obviously there for a reason but I wonder if just smooth would work or would you get too much blow out?
I have the manicat out of the car and so far I've drilled through one stud, I've tried bolt extractors in the hole but nothing, I assume I'll have to drill the bolt out and use a tap and die set and probably a heli coil to make it useable again?
What would you do taking into account that a new manifold will be quite expensive due to having the CAT attached to it.
Would a machine shop likely be expensive?
Could you get away with no thread in the hole and just put a bolt through it with nut on other end. The thread is obviously there for a reason but I wonder if just smooth would work or would you get too much blow out?
If you're careful, you can drill the old ones out and run a tap through the hole to clean it up. But you'll often bork the threads a bit.
Options then are to drill and tap to a bigger size, if there's enough meat. A helicoil. Or as you say, a nut and bolt.
Assuming we're talking about two flanges being pressed together (fnaaaaaaar), a through bolt and nut will be just as effective as a bolt into a tapped hole. The reason for using a tapped hole is because it's less fiddly to do up, rather than because it's structurally better.
If you want to be really ghetto, use a through bolt and tack-weld the nut onto the back of the flange
Options then are to drill and tap to a bigger size, if there's enough meat. A helicoil. Or as you say, a nut and bolt.
Assuming we're talking about two flanges being pressed together (fnaaaaaaar), a through bolt and nut will be just as effective as a bolt into a tapped hole. The reason for using a tapped hole is because it's less fiddly to do up, rather than because it's structurally better.
If you want to be really ghetto, use a through bolt and tack-weld the nut onto the back of the flange
That's great to hear that just a nut and bolt will work, I'll use washers to beef it up a bit also. That's really saved me a lot of hassle. I'll just drill the hole out bigger and use the nut and bolt without tapping then.
Regarding the nut and bolt, what properties will I need to use for these heats, which grade of steel etc?
Regarding the nut and bolt, what properties will I need to use for these heats, which grade of steel etc?
RR76 said:
That's great to hear that just a nut and bolt will work, I'll use washers to beef it up a bit also. That's really saved me a lot of hassle. I'll just drill the hole out bigger and use the nut and bolt without tapping then.
Regarding the nut and bolt, what properties will I need to use for these heats, which grade of steel etc?
A normal 8.8 high tension nut / bolt will be fine. Some older stuff used to use brass nuts, to prevent rusting, so we're not talking a huge amount of torque - there's no requirements for extra special strong steel or anything.Regarding the nut and bolt, what properties will I need to use for these heats, which grade of steel etc?
ChocolateFrog said:
As others have said if you can grind off both ends you should be able to separate them and then just use nuts and bolts.
I tend to use stainless ones as then you've got a hope should you need to remove them again.
I don't use stainless fixings if I know they need removing, as they are prone to galling.I tend to use stainless ones as then you've got a hope should you need to remove them again.
RR76 said:
Out of interest, what would a garage do if these studs snapped while they were replacing the exhaust, would they drill out new holes in the manifold flange or would they charge the customer for a new manifold/cat?
Depends very much on the garage; the skill levels of the staff, how much they like fixing things (as opposed to simply fitting new bits), how much they value the customer and respect his wallet, but also the cost differential between fixing/replacing including the efficacy and expected lifetime of the repair, and ultimately, their own policy... eg I very much doubt that main dealers would 'fix it up' over replacing it.AIMHO
RR76 said:
Out of interest, what would a garage do if these studs snapped while they were replacing the exhaust, would they drill out new holes in the manifold flange or would they charge the customer for a new manifold/cat?
Depends very much on the garage; the skill levels of the staff, how much they like fixing things as opposed to simply replacing stuff (the difference between an engineer and a fitter), how much they value the customer and respect his wallet, but also the cost differential between fixing/replacing including the efficacy and expected lifetime of the repair, and ultimately, their own policy... eg I very much doubt that main dealers would 'fix it up' over replacing it.AIMHO
gazza285 said:
ChocolateFrog said:
As others have said if you can grind off both ends you should be able to separate them and then just use nuts and bolts.
I tend to use stainless ones as then you've got a hope should you need to remove them again.
I don't use stainless fixings if I know they need removing, as they are prone to galling.I tend to use stainless ones as then you've got a hope should you need to remove them again.
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