Back in Febuary I took my FD to a "reputable" rotary performance shop to have some work done. When I picked up the car the mechanic said that my car was running the wrong radiator cap (1.3 bar). He replaced it with the "right" one (0.9 bar). Stupidly I didn't question it. Honestly, I didn't really understand the difference back then. 9 months later now, guess who needs an engine rebuild due to coolant seal failure... Now that I understand that a lot of people feel that FD's should have higher pressure caps I wonder... Is this coincience or sabotage? What do you guys run and why? I would like to hear opinions. Thanks.

 

0.9bar is the right one!

 

Yea, 13 psi is right man.

 

Sorry to here aboout your ening problems, but you arn't going to be able to blame it on your mechanic changing out your coolant cap back in Febuary. .9 (13psi) is the proper cap.

 

It's my understanding that Mazda, in one of it's recalls, changed the pressure cap from 1.3 bar to 0.9 bar to put less stress on the cooling system.

 

So then the other shop that had previously put on the 1.3 bar cap was wrong? I'm not blaming anyone, I just don't want to make any mistakes this time around. Thanks.

 

Coolant seals can fail for many reasons. Overheating can cause failure (never believe the stock coolant gauge), a leaky hose can cause coolant loss that will result in engine failure, and age and high milage on the engine can result in coolant seal failure. If you still have the stock engine then maybe it was just time.

When you replace the engine be sure to replace EVERY part of the coolant system while you are in there. Upgrade your radiator if you haven’t done so already. Replace every single coolant hose in your engine compartment. Replace your water pump and thermostat along with the engine wether it needs it or not. Replace both of your radiator caps and get an aluminum AST if you haven’t done so already. If you are not going to install your engine yourself be sure that the mechanic who installs it knows to do all of this. Be sure to do the fan mod and consider getting a second oil cooler if you don't have one. Last but not least, be sure to check your coolant level on a regular basis in the future. These steps will help prevent future coolant seal failure on your new engine.

One more thing that I do just for good measure is to have a box fan waiting for me at the end of the day when I get home. I pop my hood and turn on the fan to cool the car down.

 

My mechanic has a box fan in his garage also that he runs untill after the stock fans turn off (10 min ) also . He does not open the hood as Former Porsche Guy does .

 

Unfortunately coolant seals fail all of the time. Sorry, it's not your mechanics fault. Welcome to the club. BTW I run 0 psi cap with evans.

 

The 1.3 bar cap may have contributed to your bad coolant seals, but like everyone else said, they were bound to fail anyway. I have a 0.9 bar (13psi) cap on mine.

Gimme a break... are you serious? Do you seriously think that running a box fan at your engine bay is necessary? These cars are not as fragile as everyone makes them out to be.

 

Is this the pressure cap on the AST ?

 

I live in Houston and in summer temperatures here reach 95+ for months at a time. Its november and the high today is still in the mid 80's.

 

Yes

 

The 1.3 bar cap did not contribute to the failure. It takes a lot more pressure than that. Remember, the "O" rings could actually see engine compression values. Much greater pressure than the measly coolant system. What was failing, causing the cap change, was the hose to/from the turbos. The hose would burst (weakened by the radiant heat of the turbo) and would spray glycol all over, some on the turbo housing. It runs red hot, and glycol burns very well. Soooo, some cars were lost to engine fires. Mine suffered that fate at 20,000 km. The fire was extinguished before the whole car went up, so I have a car with 20,000 km less on the engine and turbos than the chassis.

 

Well, I have RX7.com aluminium AST. I hope it has the right cap, haven't checked that.