im buying a 93 FD rx-7. the guy whos selling it had told me that there is one reliability problem with it. the problem is that every so often like 2 or 3 months the "AST" will become too presurized and blow the cap off the overflow tank. I need to know what hes talkin about so i dont buy an rx-7 that actually need to have an engine rebuild or something. What is an AST, and how can i fix this problem?

AST Air-Seperation-Tank The problem probably has to do with either of the rad. caps. When they go bad they dont allow antifreeze to bypass them. Therefore the system becoming to pressurized. SHould be an easy fix pettit sells an aluminum one for like $100 and its an exact replacement. I would make certain that he has NEVER overheated the car. Also the ast is mounted onto the intercooler. Its a black plastic tank thats easily accessible.

thank you so much. he claims to not have overheated. although the old radiator did go bad so it has been replaced with a fluidyne radiator. ill be checking to see if it might have been overheated or not.

Two things, sounds like the there is a blockage in water passages, if you buy it first thing i would do is replace the thermostat, check/replace water pump, and pessure out water in the block. https://www.nopistons.com/forums/pub...IR#>/boink.gif https://www.nopistons.com/forums/pub...IR#>/boink.gif



BTW, M2 sells system ($50) that totally removes the AST, and gives it standard overflow line, like all normal cars.

You can also eliminate the ast altogther.