2001 Grand Caravan Sport, 3.3L: While trying to change the water pump, several bolts felt weird when loosening them. The lowest one broke off, leaving about an 1/8th of an inch sticking out. It's frozen in there, good.

I made a drill guide out of a piece of 1/2 inch aluminum to center a drill bit on the stub. A 5/64" drill went through fine. I then stepped up to a 7/64" drill but the edge just gets dull. The pump bolts are 6M x 1.0 with "9.8" on the head.

Are 9.8 grade bolts case hardened? And, if so, what can a person do to get it out?

About to cry

 

You are kind of in between. See this link. Should not be that hard though. New bit? Can you get a carbide bit? I am a machinist and can sharpen bits. Get a new or better one or sharpen that one and don't push hard, let the drill cut. And have some kind of cutting fluid on it even if its just a little to get her going.

I found a bolt on mine that went all the way through and had a nut put on the back so someone had a time with it before me. Serves them right for putting a pump in that had a plastic impeller. Thats why I was under there. Don't do it!

Small bolts in Aluminum Alloy are problematic at best. Be sure and use a tiny bit of low strength Blue Loctite at assembly. It will water and corrosion protect the threads and have a tad bit of lubricity for future diss-assembly.

Good Luck

 

Well, thanks. I ordered a solid carbide bit from McMaster-Carr. Will try it when I get it. The other problem is the location. The strut and brake lines are a little bit in the way, so I am using a dremel tool with these small bits. Frankly, I feel that the speed is way to fast, even on the lowest setting. I'll have to see if I can get the motor to hang a little lower for better access.

I guess the worst case scenario would be to remove the timing chain cover.

What about heating with a blow torch? I tried it a little bit, but am afraid of destroying the aluminum cover. I would like to heat the busted bolt to cherry red.

Lance

 

I don't know about the heat. No telling what else you will get too hot. Borrow an angle drill?

You're in a tough spot. Higher speeds are the enemy for you right now. Plastics and aluminum yes but fastener metal?

 

Yay! I finally got it. I bought a right angle compact drill. I put the old pump back on to aid as a drill guide. Then I made drill bushings for the fractional sizes and the last drill, which was 5 mm for the tap. The drill bushings have a shoulder and a short stub that sits in the water pump hole. They did a great job of keeping the bits centered. I used all new bits to make sure they were sharp and cutting oil. I didn't even have to tap. I ran the 6mm tap right through just to clean up the threads.