Broken (twisted off) water pump bolt on 1978 280 Z.

[varn]

When replacing the water pump on my 1978 280Z one of the larger bolts (8 mm) twisted off. It's the one below and to the right of the large rectangular water pump flow hole. This happened even though all the necessary precautions were taken like striking the bolt head with a drift and hammer prior to removal. And, trying to slightly tighten and loosen the bolt prior to trying to remove it.

Anyway it twisted off. Upon removal of all the necessary parts (timing case cover, oil pan, valve cover, distributor, etc.) it was discovered that this bolt is twisted off flush with the face of the block. So, it cannot be "grabbed" with a tool and twisted out.

So, for several days, I used the super duper rust disolver liquid spray to try and disolve the rust in the threads prior to using an easy out. It was soaked and soaked with this spray.

Next, I drilled a small centered pilot hole in the very center of the broken off bolt. Then, using this pilot hole as a guide, I drilled a larger hole in this broken off bolt. Next, I tried a small easy out. But, it did not budge the bolt. I was somewhat hesitant to twist with extreme force because I have broken off easy outs before and this only complicates the removal processes. Next, I drilled out the hole a little further and tried a larger easy out. Still no luck.

Maybe if I applied some heat to the area that would work?

My next step, is to drill out the bolt with a drill that is slightly smaller than the minor diameter of the threads so as not to remove much of the threads in the block. Then try and use a tap (same size as the existing threads) to remove what is remaining of the bolt. I have not gone to this next step yet.

Will this work or am I just wasting my time?

How are these bolts removed?

What about the metal shavings? Can these particles be flushed out since the whole front of the engine is now exposed and open?

[navysnail]

i would use the easy out and try your best to make that work, it will take some force. as far as metal shavings go, try to put somthing under it to catch as many as possible, any that get by will be taken care of by the oil filter

[DAEDALUS]

You can also use a strong magnet or 2 to catch the shavings.

[navysnail]

i thought about that, but is the pump or block on that aluminum, i dont think so but if it is, that wont work

[s13sr20chris]

if you have to tap new threads dont worry. it is not too difficult. will you be able to pull the oil pan and clean it out? if so, you can wash some shavings down into the pan before you pull it. just remember you could always drill slightly oversize and use a helicoil insert. that is way preferable to breaking an easy out.

[varn]

The block is cast iron or steel. So, magnets will work. I just have to find one small enough to go down that 8mm hole. I think that the bottom of that particular hole is open to the water jackets inside the block. I can stick my finger into the large water flow hole (that goes to the water pump) and feel the back of that hole. So, I think I can put a magnet of some kind behind that hole.

[varn]

I have already removed the pan. Had to to get the timing case cover off. Also, had to take out the distributor and oikl pump in order to remove the timing case cover.

By the way, how do you tell if the timing chain needs replacing? Now would be a good time for me to do that. I don't think that it has ever been replaced. The engine now has just about 113,000 miles on it. That's original miles too. I guess for a 1978 that's now a heck of a lot of mileage. That's an average of about 113,000/(2005-1978) = about 4160 miles per year.