I have a built 496 with forged internals, 2.3 whipple with a large aftermarket heat exchanger.... etc. This boat has ran perfect for 4-5 years. My mechanic is having trouble with getting the bushing below the heat exchanger not to leak. He has installed a brand new , Mercury part 3 times now and all the bushings end up tearing after they have been installed and ran for bit....... and it starts leaking again. It just a poor design. Any helpful hints?

The mounting flange for the bushing on the port side of the crossover isn't fixed, it can move to get the spacing just right for the specific heat exchanger. (This is also where the thermostat mounts) I also run the aftermarket 5" SenDure exchanger on my 496. Install the heat exchanger with new seals onto the crossover, and then tighten the port mounting flange bolts. It's a little tight but you can still get to them.

Also, make sure your coolant reservoir isn't in contact with the heat exchanger. You may need to notch the mounting points of the coolant reservoir to move it back a little.

Thanks for your response...... With the help of your response...... this help fix the problem. Thank you!