I desperately need some good news. In absence of good news, I need advice.

General info: '91 RX-7 convertible, no modifications, 130,000 miles.

Problem: Coolant disappearing, causing overheating.

I've shut down the engine the minute it gets warm, but I can't figure out where the coolant is going and why it's not moving around. The reservoir remains full, but I keep having to fill via the filler neck.

My local garage, who are good guys but they admit having never worked on rotaries before, pressure tested and could find no leak in the radiator, water pump or hoses, DARN!

They did say my radiator cap doesn't fit really tight, but they think it's water seal issues. Gosh, I hope they are wrong! But I have to say, it all seems to point that way.......

but....why doesn't the fluid go from the reservoir to the radiator? Why does the reservoir remain completely full? Is it possible that the water pump is not pumping, not leaking, and not making noise? could the water pump simply not be doing ANYTHING? How would I find out?

I went to the FAQ about checking your water seals. When I open the cap as said, a LITTLE water pops out, but not a LOT. Probably not more than a cup's worth. Any other ways to check the water seals...not smelling anything odd, but then I'm not sure I'd know. Any experts in or near SW Michigan willing to come and take a look?