Every time i open my stat cap i always found that my coolant drop little bit not much about 1/2 oz I top it off drive it for a few days open the cap and same thing happen.Car never over heat i check all the hose no leak any were change the cap on the Pitti AST and thermostat housing cap also still same issue.Can it be that my water seal is going? When i started the engine i saw some smoke for a few second not alot on a warm days did not smell any sweet coolant smell from the tailpipe no white smoke when i WOT the car.Any ideas what to check next? By the way i use EVAN waterless coolant.

 

How many miles on your engine?

 

I'm not sure about FD's, but I used some alumiseal in my FB & my coolant issue disappeared. I was loosing it & smoking on cold start, search it a bunch of us can vouch..... GL!

 

I would think it is 1 of 2 problems.

1. You have air in your system, and it is slowly being purged out. You can purchase a coolant filling funnel to make sure all air is out. http://www.amazon.com/Lisle-24610-Sp.../dp/B001A4EAV0

2. You have a coolant leak somewhere. Rent a coolant pressure tester from Autozone/AdvanceAutoParts/Pepboys/etc... Use this to test and makre sure your system is holding pressure, otherwise you have a leak somewhere.

 

Thanks i'll check it out.

 

i had the same problem in my FD, was not the cap but just a little plastic in wich you lock your cap. After replace with an alluminium one (now Mazda provide only alluminium) solved the problem.
Try to looks better this plastic item
Pietro

 

Try doing a coolant system pressure test. They usually help in identifying any leaks. Sometimes the pressure tester doesn't work very well though and leaks so you may get a false positive but usually it helps.