I am sure some of you have heard this story before. Woke up this morning, set aside 10 minutes to change the thermostat to 180 run a bit cooler and get some performance (not much LOL). So you go to turn the bolts out, one comes out easily. The second one... SNAPS. Ah Shiatie. So what to do?? E-Z out?? Sure, but don't want to snap it in the bolt. So, you decide to re-tap it.

Now, I want to do it, and have drilled it with 1/4 bit and its straight in. I am careful not to drill into the water passage. So, what size should I use to re-tap that hole. I am not really good with sizes and I am looking at the bolt and the re-taping sizes and I have two. One is a bit smaller than the bolt, and the other is about the same size, a bit bigger. Now I don't want to f' this up. So, if you guys can just tell me what size that hole should be I'd appreciate it. My reasoning is that some of you have to have done this before. I searched but did not come up with a size. I am just trying to do this right, and I have two sizes and don't want to spend 20 bucks a piece per one size.

Thanks a bunch.... THanks.

 

The bolt size is 3/8"-16.

Go to the parts store and get that size Heli-coil kit. It will tell you what size hole to drill for the Heli-coil. There's NO WAY you'll be able to drill it out and re-tap it to the original size, with what metal remains. That's why the bolt broke off in the first place, is because THERE IS NO METAL THERE ANY MORE, it's all turned to rust and oxidation.

 

Thanks, I figured out the size on the stores little chart. Got that heli coil. I dremeled whatever was left of the bolt in the hole. Tomorrow I'll get the 25/64 bit and I'll try to heli-coil it.