ok i have a 78 20r and i was hearing a ticking and discovered that
the rear (close to the firewall) of the header is missing the nut and
bolt. i was also looking and 1 or 2 of the other ones were loose. so
my question is how do i replace the broken bolt. or should i tighten
down the other ones and wait till i replace the header all together.
2006 4x4 Access, V6, 6spd, TRD Off-Road, tow pkg. Donahoe Co's, TC UCA's, Dakar leafs, 5125's in the back and u-bolt flip kit. TRD exhaust, CAI. URD MAF calibrator. 17x9's, 285/70/17 BFG MT KM2. Locker-mod, fog mod and console vault.
if it is broke and there is still some bolt sticking out remove the exhaust manifold. Then put 2 nuts on it tighten down the 2nd one on the first then put a wrench on the first one and remove the bolt. If there is not enough room for 2 nuts and only enough for one, put it on. Then tack weld it so that it makes a bolt and remove it. If there is no room at all you will probably have to remove the head. If there is no bolt in there chase the threads with a tap and get a stud. Studs are better cause they concentrate the clamping force on the threads and the nut rathe then the weak alum threads in the head. If the threads are stripped in the head you got two choices. Tap the hole and install a larger bolt, maybe a standard size, or inst a helicoil.
sorry, thats air force mechanic talk. Install a helicoil means drill out the threads and tap bigger ones to put in a helicoil. when you get a helicoi kit it comes with the tap, helicoil and bit to drill out th e hole.
i just had the same problem with my '76... the studs stripped out the threads inside the head, i think i had to retap four of them. all mine were loose as well because the previous owner new they were stripped out.
alot of people have told me that the exhaust studs are notorious for pulling out like that around the 70's era trucks, i dont know if thats true thats just what i have been told.
new studs and thread-lock fixed it for me, good luck on yours.
Not sure bout your exaust ports. But on mine i have about 6 studs coming out of the block. If it was me, I would probably either drill it out and tap it for a bolt. Or drill out the hole on the exaust manifold bigger, and weld on a studd to the block. But thats kinda redneck. lol
I agree with toyota man. If there is enough bolt or stud left to weld a nut on it through the center of the nut it will work. The heat from the weld will expand the stud or bolt, so you will want to cool it off before trying to remove it. I've used this technique many times on old farm equipment when a stuck bolt from rust is broken. the expansion, then cooling will break and free the rusted bolt.
Be careful if you want to re-tap the hole if your head is alluminum, you'll need to use varsol/paint thinner as a lubricant, DO-NOT use cutting oil as it will gaul the new threads. Using a heli-coil is a standard practice were I work, Steel smelting, they can take the heat if done properly.
You should also use some pennitrating oil on the stud befor trying to remove it - makes it alot easier to take out without gauling the internal threads as bad.
Welding a nut to the stud dose a good job, be careful and work the stud in and out, taking your time.
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