reinstalling exhaust header studs
05-13-2012, 09:00 PM
#1
Race Car
Thread Starter
Join Date: Mar 2012
Location: Austin TX, drinking beer in the garage
Posts: 3,602
Likes: 0
Received 7 Likes
on
7 Posts
reinstalling exhaust header studs
I accidentally lost one of my exhaust studs while I was mucking around and trying to tighten it down to fix a slight exhaust leak I had. I removed it to inspect it, dropped it on the ground, and it was never seen again. oh well. I got the new stud and copper lock nut today, and my question is, do I have to pull the entire header set off or do something crazy like pull the head in order to get the stud back in properly? Maybe I'm just not doing it right. I just spun the nut onto the long side of the stud and then hand screwed it a few times into the head, but when I started to apply torque it seemed like maybe it wasnt in correctly, and since I cant see at that angle, I really wasnt keen on stripping the soft aluminum. Somebody tell me I'm stupid and that I just need to get a wrench on that nut and a small angled mirror on a stalk so that I can see, and torque the SOB down.
05-13-2012, 09:40 PM
#2
Rennlist Member
Hmmm... Make sure you check in the exhaust port and in the headers for the lost stud. Wouldn't want to find it the hard way... 
As for installing the new stud, you made reference to putting "the nut" on the stud. What you want to do is get two regular old M8 nuts and put one on just far enough so that you can put the second nut fully on the thread. Then tighten the nuts against each other with two wrenches -- nice and tight. This way the outer nut is tight on the stud and won't spin, so you can use it to screw the stud into the head. Having said that, the stud should screw in fairly easily and you should not have to force it or turn very hard. If it seems to be very tight, then in order of likelihood, either: (a) the header flange you are screwing through is not lined up well, and as a result the stud is not going in the hole straight enough, (b) the threads in the head are dirty or damaged, or (c) you cross threaded the stud and are screwing it up worse with every turn. If the stud it tight, start by loosening all the other nuts at the head and cross-over -- until the headers are very loose. With the extra wiggle room, now try lining up the stud and screwing it in. If its still too tight, then I'd probably remove the headers and confirm the stud screws in nicely without the header in the way. Assuming it does, then it's just a matter of reinstalling the studs in whatever order needed to avoid binding on the headers. If, on the other hand, you pull the headers off and the new stud still is not screwing in nicely, then its time to run a thread cleaning tap in the hole. If for any reason the threads are stripped beyond repair, then you'll need to install a helicoil or timesert, which in theory can be done with the head still on the motor, but in practice may be easier with the head off...
As for installing the new stud, you made reference to putting "the nut" on the stud. What you want to do is get two regular old M8 nuts and put one on just far enough so that you can put the second nut fully on the thread. Then tighten the nuts against each other with two wrenches -- nice and tight. This way the outer nut is tight on the stud and won't spin, so you can use it to screw the stud into the head. Having said that, the stud should screw in fairly easily and you should not have to force it or turn very hard. If it seems to be very tight, then in order of likelihood, either: (a) the header flange you are screwing through is not lined up well, and as a result the stud is not going in the hole straight enough, (b) the threads in the head are dirty or damaged, or (c) you cross threaded the stud and are screwing it up worse with every turn. If the stud it tight, start by loosening all the other nuts at the head and cross-over -- until the headers are very loose. With the extra wiggle room, now try lining up the stud and screwing it in. If its still too tight, then I'd probably remove the headers and confirm the stud screws in nicely without the header in the way. Assuming it does, then it's just a matter of reinstalling the studs in whatever order needed to avoid binding on the headers. If, on the other hand, you pull the headers off and the new stud still is not screwing in nicely, then its time to run a thread cleaning tap in the hole. If for any reason the threads are stripped beyond repair, then you'll need to install a helicoil or timesert, which in theory can be done with the head still on the motor, but in practice may be easier with the head off...
05-14-2012, 12:06 AM
#3
Race Car
Thread Starter
Join Date: Mar 2012
Location: Austin TX, drinking beer in the garage
Posts: 3,602
Likes: 0
Received 7 Likes
on
7 Posts
Tom, I've been running the car like this for months now, daily driven. I never did recover the old stud but I'm fairly certain its either (most likely) not in the car at all, or lost somewhere in the nooks and cranies of the engine suspension. I think if it was in the headers or in the valves somewhere I would have had a bad day by now. I dont hear any kind of rattles. There is also very little carbon blowback around the part of the gasket that has been missing a stud, and my spool up was unaffected, so I guess the headers are still making a good seal. The only reason i discovered the leak at all was because I was doing a routine visual inspection and I noticed one of the copper nuts seemed loose. I backed it out with the nut still on it to clean the threads up and reinstall it, and I dropped it. took me a few months to bother putting a new stud in it.
you make me paranoid though..should I pull the headers off? I've never done it on my turbo, how much more of a pain in the *** is it as compared to a N/A?
you make me paranoid though..should I pull the headers off? I've never done it on my turbo, how much more of a pain in the *** is it as compared to a N/A?
