1987 Coupe DeVille - Cracked Block?

About a year or so ago I helped a friend of mine by replacing the water pump on his 4.1 V-8 DeVille. About 10 months later the water pump bearings were going bad again, and since he had warranty from AutoZone, I figured we can replace it with another one. But since I was leaving for my vacation for 10 days, all he could do was keep on driving it and to add water if it went low, as well as watching the gauge to see if it got hot. I also advised him to be very carefull with it as he could damage the engine.

When I got back, he told me that his car was parked at his work because it was pouring out coolant and that he was going to drive the companies truck for his transportation. I went to see the car on Saturday morning, got the water pump out, and got a replacement. This time, when I was trying to install it, I had a hard time putting it in, plus it was getting dark. So I figured, I'd continue the next morning. I cleaned the old sealant (copper stuff) off the water pump and the gasket. This time I used the proper water pump/thermostat housing sealant and I carefully managed to get it on. Now I had another problem! The water pump was not going on flat on the block! :banghead: It was wiggling... So I took it out again. Went and bought some more of the sealant as well as a new gasket. I cleaned the area on the block, as well as the water pump, found out there was a broken bolt stuck in the block and made sure it was not going to cause any other problems, and put it back on! This time, it went on right! I finally tightened the bolts. Started to add some water in to see if it leaked... And bam.... It was leaking 3 drips per second again!!! :sly:

Drove it to AutoZone, to see if they could tell me if I did anything wrong (the manager knew the Caddy 4.1 engine very well) and he recommended me to ask his mechanic friend outside. So I did. When the mechanic and his friend saw the engine, they told me it more likely a crack in the Aluminum Block (apperantly they are notorious to cracking) and that I could try this Block Repairing stuff...

I had the car towed at my expense, and am planning on finding out what happened to the car. But I thought I'd ask before I get there again.

I can tell you that when the water pump was out, water was coming out of the middle hole when I poured water in the radiator. There was no visible crack on the block. And it was leaking alot even without any pressure in the cooling system.

Does anyone have any ideas what the problem could be? Any way of testing the system to see if the block is actually cracked? Anyone have any instructions from a manual or something about how to install the water pump? I am at a total loss right now.

Thanks,
Jason

You probably just need to use sealant on that bolt. I'm not familiar with the 4100, but many times the threads are not blind-tapped and they go straight into the water jacket.