HELP!!!! Water Pump Mounting Problems!!

[restorationboy14]

Ok heres the rundown I was replacing the water pump on my '69 GMC pickup ( 292 inline 6) when i was taking it off the bottom driverside bolt head broke off and I drilled the bolt out and retapped it to 3/8 and I drilled the hole in the water pump to 3/8 so the bolt would fit. I went to put it on and ITS NOT LINING UP!!!!!!!!!!!!!!! Why is this????? HELP!!! Thanks for the help!!!!!!

[BOHICA-Chevy68]

it sounds like your drill bit creeped on you as you were drilling it. I had the same problem, minus the miss alignment, with my 250 block. except when I was retapping it my tap Brock off in the block. drilling out a tap is almost impossible, especially with the engine still in the truck. I'm pulling the motor and going to a 350 as soon as its built. So I just remounted to water pump minus the one bolt and will deal with a potential small water leak until I can swap.

in your case try going larger on the water pump hole by a 1/16 of and inch. start that bolt first, but leave mostly out. the start your other three and work them all down slowly. make sure it's hitting flush to the block. and stop if you get too much resistance as you could end up in a bigger problem.

[restorationboy14]

Alright thanks! Anymore advice would be much appriciated

[luvbowties]

Originally Posted by restorationboy14

Alright thanks! Anymore advice would be much appriciated

If you are very careful--esp. re:physical finger harm--patiently, using a bench grinder, with bolt chucked into and being spun by a hand drill, "turn down the threads" on your bolt so the bolt is just slightly smaller in diameter. Then clean up the threads with the proper die. Along with Chevy-68's advice about drilling a bigger hole in your pump, you have better chances of the bolt going in AND relatively straight. Dip the bolt completely in leak-sealant, like you use on head bolts. If you can find a copper gasket(washer-type)kinda like used on oil pans, use it too.
Remember, this is now a 'crippled'--no longer a primary--hold-down bolt. But by using all the suggestions so far, you should avoid having to remove the engine.
*Should it still not start/line up, you may extend Chevy-68's good advice by enlarging ALL the holes.*
Luck,
sam

[BOHICA-Chevy68]

I wouldn't drill out the other hikes just yet. the water pump has to sit just right. the fan blades go into the water jacket. if its moved over one direction too far the water pump will hit the water jacket. you do want it to sit flush though. your new hole shouldn't be off more then 1/16th of an inch if you drilled to one size larger. you want the factor holes that were in molested to be your starting point when mounting to ensure the pump sits in the water jacket the right way.

[restorationboy14]

Thanks for all the help guys! I ended up messing with it and have the bolt in with ALOT of liquid gasket.

[LONGHAIR]

I would never reduce the diameter of a bolt that threads into cast iron or aluminum. That is just asking for trouble.
In an emergency like this, I would open the hole a bit more in the correct direction, not just drilled bigger. Use a die grinder or dremel tool only on the side needed.