Water issues
 

93 fd losing water - for some reason I am losing water/coolant but there is no sign of water under the car, i'm hoping that my seals haven't gone but as they were replaced under a year ago they shouldn't have!

I pulled the engine to reseal the sump and put engine back in, hooked it all back up and started the engine. It's a little bit rough on idle as expected and a bit smokey, also noticed my air pump isn't working which could cause the smoke from exhaust.

Back to the point - I have put an aftermarket (cheapy) thermostat in and brought the car up to running temp, on the gauge it shows normal but checked the actual temp and its still cold, after switching car off and leaving for a day or two I go back to it and the level of water has dropped and have add coolant light on! I've repeated this process over 3 weekends! I've made sure on all top ups that there is no air bubbles and heaters open and also checked for any fizz in the cap but nothing!

Could it be the thermostat? Or have I missed something! Can someone help please? Thanks!

ALWAYS... ALWAYS use an OEM Mazda thermostat. Cheap thermostats and "racing" or "high performance" thermostats will not suffice. Also, when mixing water with your coolant, use demineralized water.

You need to pressure test your water/coolant system.

If a large enough amount of water is "disappearing" into the engine after sitting for a day or two, it will be very difficult to start. You'd need a very significant internal leak for it to make it into the combustion chambers when the engine is not running (cooling system not pressurized). Most leaks will happen when the system is under pressure.

In your case, I'd bet there is an external leak somewhere that you're not seeing. The FD engine bay isn't exactly the most spacious. Pull intake parts, etc.. to get a better look and either pressurize the system with a tester ( ) or while the engine is idling.

oEM is the way to go sir.

Thanks for the advice, ill get onto a new thermostat asap. Can't afford a pressure test kit at the moment but i'll blast the car around the block and jack it up to see if anything is dripping! Thanks for the advice everyone! These cars don't half test your patience, im just glad I like a challenge :-)

You can borrow a pressure tester from autozone for free

Thanks for the advice, unfortunately there are no autozones in the uk! Works out cheaper to buy one than rent one here, all money grabbers!