So the '79 DL spew a little water out of the radiator for a moment the other day, so I decide to change the thermostat and add some of that aluminum stop leak to see if it will work. Whilst unbolting the thermostat housing, went well at first, then it got tight while loosening, tried to retighten,then, cRRRRACK!!! I snap the bolt head off of the top bolt. WHAT is the best way to remedy this problem? Should I saw the bolt off and JB weld?(probably not). Saw off bolt and drill out? (how will I get the threads back?) Realize I'm not a mechanic and pay someone to do it?(requires tow then:mad: ).

 

You know you're a Gen one owner if, you're afraid to fix anything anymore, for fear of breaking bolts. (about my 6th on this car)

Is there still some of the bolt sticking out?

Is there still some of the bolt sticking out?

Yes about a 1/4 inch.

not familiar with this part...

 

can you hacksaw a slit in it and turn it into a flat head screw?

If you're good with your hands, you could do a couple things:

 

1) Try to get a pair of vise-grips or a good set of pliers and just try to back the remainder of the bolt out. A 1/4" isn't very much, so vise-grips might work better. However, if this doesn't work, don't keep messing with it and tearing the remainder of the bolt up worse...

 

2) coz you can Dremel a slit in the top of the remainder of the bolt, large enough for the head of a flathead screwdriver to fit in, and try backing it out that way. Edit: Just like uncoolperson just said

 

Always try one of these methods to unscrew the broken bolt naturally, before you start drilling and tapping.

Apply PB Blaster penetrant oil, heat if you can, a tap or two with a hammer/mallet, patience, repeat over the course of a day or so. Sears and others sell special sockets that grab stubs and broken bolts (sounds like this would be an oft-used tool for you ), otherwise vice grips or weld on a nut. If the bolt head broke off from the torque, it is unlikely that slotting for a screwdriver will do any good.

 

EZ-Outs/Screw-extractors are the Devil; break one off (REAL likely) and you are looking at machine shop work or replacement head.

Major f'ing +1 on no screw extractors. The chances of you breaking them off are 99.99999992673%, and once you do, that's it, you can't drill into it or any other fancy stuff.

 

Unfortunately, NorthWet also has a good point about the fragment being corroded into the head. I've ruined bolt heads trying to get them out, and then I ended up Dremelling the head off, separating the two parts, and screwing the fragment right out. In that case, it was the bolt head that was corroded onto the flat surface, not the threads. But if it's the threads themselves that are corroded, then it's going to be just as difficult for you to break it loose as it would have been if the bolt had remained intact. Tread lightly.

 

Lots of PB Blaster, lots of PB Blaster.

PB applied before, during (after it tightened up about 1.5 unscrews) and after. I think the bolt may of protruded out of the back of the housing(hard to see), and I dind't PB there originally. I think rusty threads got me on the way out.

 

Thanks Northwet for the Sears advice on the backer-outer. BTW, this is the only car i have broken bolts on, It just sat for about 13 years out in the open. Only 60K miles original though.

 

Wow, after looking, I'm not sure what one to get:confused:

 

http://www.sears.com/sr/javasr/subcat.do?vertical=TOOL&cat=Hand+Tools%2C+General+Purpose&subcat=Bolt-Out%2C+Taps+%26+Dies&BV_UseBVCookie=Yes

 

Ok going out to pb blast and tap a little, then going to bed. Thanks for all the advice so far.

Forgot that you had mentioned that you had gotten some movement on the bolt before it broke (or was it just twisting off its head???). If possible, soak with PB and then try screwing it back IN. Try working it back out/in, making sure plenty of PB is available, and see if you can gradually work it out.

Had the same problem on my 78 Brat. Sprayed some WD-40 on it and put the vise grip on it. Came right out.

FINALLY, it's out. I guess all you really need is PB and a manimal. I couldn't squeeze the vice grips tight enough, and they just kept slipping. Then I called my friendly neighborhood manimal, arms the size of my legs. Ever so slowly it came out, but now I need to re-tap the hole, due to the fact that the threads are slightly outta wack.

You can probably retap them to the original size.

 

Use kerosene as your cutting oil, make sure the tap is straight in, do it very slowly, and clean up any shavings thoroughly when you're done.