Duck

Hi everyone,

Well I had a time removing the heat exchangers this winter. I ended up breaking several studs. I was lucky to find a jig that helped tremendously drill out the ones broken off too close. So I replaced all the studs with new ones. The bad thing was that on one of the hex barrel nuts, I did not get the stud all the way in. I guess after working so hard to get everything off, I rushed and did not pay close attention.

I got the heat exchangers back on and when tightening the one hex nut, I got to a point that the hex wrench spun. The stud was out too far and therefore I lost almost all the gripping surface.

The heat exchanger seems to be in pretty good. The first question is should I tackle this now or wait till I have the engine out for a rebuild? The second question (if I should tackle it now) is there any ideas how I could get the hex nut off when I cannot get any grip with a hex wrench?

Any assistance is greatly appreciated.

Duck

springer3

I would not even consider driving with a loose exhaust flange nut. At WOT, hot exhaust will cut slots in sealing flanges of the head and exhaust manifold as it escapes on the loose side. Possibly you will warp the exhaust manifold. If either happens, there is no hope the system will seal properly without some expensive machine work. Drill out the bad nut, take the heat exchangers back off, and get that stud in correctly.

elbeee964

Springer-
Along the lines of this thread...
I've heard PPI's report back loose/pulled cylinder bolts but don't recall hearing about loose (or worse yet, missing) exhaust flange bolts.

But this thread brings to mind how do you check for either of these two important fastener's health while you're under there taking a look around?

Is an owner's inspection as simple as hand-trying each?
If it feels solid -- it's good?
FWIW, I can see my exhaust studs (ugly as they are) every time I go underneath but have never tried spinning them.
And I've never tried going about checking for 'pulled'/loose cylinder studs. (Wouldn't know how!)

(jeez, this question mushroomed on me... Perhaps I should post this self-check question, instead, as a stand-alone thread? lol)

thanks,
-Lonnie

Duck-
I feel for ya, brother. Sounds best to bite that bullet.

stevepaa

I can not remeber if those hex nuts are magnetic or not. Maybe you will have to spray some brake cleaner up there, let dry and then stick epoxy on your hex wrench and stick it into the nut and hold unitl it sets up, so you can pull back on nut as you try to unscrew it?

dutchcrunch

on reinstallation use anti seize.

remove another barrel nut and find the biggest drill bit the will go into the hex without touching the walls. then drill stud on that one you are having problems on, you only need to remoove a 1/8 t0 3/16 for the allen to bite and then you can remove nut, and replace stud .

Duck

Thanks everyone. I was thinking this was the case. It is just difficult to get back under there after it sat on jack stands for so long. I hope I can find a drill bit that will work. Since I will be on vacation all next week, I will tackle it when I get back.

springer3

I had a better idea after thinking about this. Remove the nuts that will come off. Use the weight of the exhaust header to apply pressure while you turn the nut. With any luck it will find some threads and come off. Worst case you still need to drill it.

dutchcrunch

Springer3, i think he meant that the stud is comming thru the barrel nut. the barrel nut is hollow as you know, and basically he treaded the nut to far on the stud and as the stud came thru it pushed the allen key out. he did not install the stud deep enough in the head. that is why he is having this problem. so he cannot tighten the nut anymore because the stud is in the allen key hole.

Duck

Yes, dutchcrunch is right. I had gotten it fairly tight before this happened. What is annoying is that I was really going back and giving them one last tightening check when it happened. So I know it is fairly tight, however not sure how tight. I did use antisieze on it, however I cannot get the allen key to catch to loosen it back out. I tried from the side with small channel locks, however it is just too tight.

I will try to find a long drill bit and go that route.

It is a lot of work that I was glad when I got it back together. Now I need to be a little more careful next time.

springer3

I snug up any fasteners I can reach any time I am working on the car. I do it with trepidation, because if one is loose or stripped, it can mean a major unexpected project.

You will not damage a healthy fastener by taking it up to 75% of original torque - enough torque to know if it is loose, but not so much that you will damage a fastener that can still get the job done.

I don't recommend backing off a fastener just to check it by torqueing it again - too much risk that a stuck nut will turn the stud and damage threads in the aluminum.

elbeee964

Sounds righteous, Springer!
Will try that out when I dust up the coveralls going under the car, next time.

tbennett017

If I read this right, and if I get the vision, what you are suggesting is to drill the face of an allen tool, to allow room for the stud to stick "into" it while it reaches the female allen face, to loosen it.

This makes a lot of sense. I am just checking.. Duck, you actually don't need a long drill bit for this. The only problem I see is that the allen key will likely be hardened, and thus kinda difficult to drill well. YOu will want a drill press and a very well secured setup to keep it from moving around.

You might check to see if there is a custom tool that will work for this. Check out Griots Garage, as he has a set of "security" fasteners, for allens that have precisely that.. a stud up the middle to keep any old yahoo from using a tool on it. I know the 8mm (right?) is a bit big, but you never know.

I would try drilling one.. or check with a machinist to see if they can do it for you, since hardened steel is not the same thing to work with.

Just my devalued $.02

dutchcrunch

Mr. Duck, was up!!!! i am in a good mood today, how about you?

anyways, you said you were able to tighten the nut. well here is a simple solution and if it does not work nothing lost. more than likely the stud coming thru is not flush with the nut. if you look at you allen wrench, specifically the tip that you insert into the barrel nut, you will notice the end has a slight chamfer to it, not a sharp edge. take it to a grinder and take off about 1/8 inch to remove it, so the hex of the allen wrench size is consitant all the way to the end, make sense?? so lets say the chamfer is 1/8 inch. that means for that amount you will not have any bite, but if you grind that part away you have the true size of the hex immediatly. when you grind it down do it slowly and if there is any sharp edges take some sand paper or a file and hit the edges lightly to remve that little edge. that way you will have a little more bite to it. when you use it make sure you are square and put some pressure upward while turning, should come loose. good luck

also there is a little trick that you can use on screws and nut ect to give you more bite, go to auto zone napa, or whoever sells auto parts and but a tube or small can of valve lappin,g/grinding compound.... it is cheap 2-4 dollars and coat the screwdriver tip or allen wrench tip and that will give you more bite, really works good on philllip head screws.

dutchcrunch

hello tbennett017,

i was implying that he drill the stud not the allen wrench, but you had a good point so i went out and checked the clearance. its to close. the allen size is 8 mm and the stud is large too so if you were to hollow out the allen you would only have just the corners. had the allen size been bigger you would be on to something. good idea, but in this circumstance its a no go.

actually if you wanted to drill the allen, if you had a lathe or go to a machine shop the could chuck the allen wrench up and drill dead center into the allen for cheap, and probably take 10 minutes or less to do it.

anyways good thinking

dutchcrunch

i did check my allen wrench and there is a definate chamfer on it, i would take a picture but the wife had my camera, i need to buy another. i will post a picture later tonite. definatley enough matereial that if it were removed it would give you more depth into the keyhole.


come on summer time, tired of this winter stuff